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This chapter describes the commands used to manage the router system and its performance on the network. In general, system or network management falls into the following categories. The categories are described in this chapter unless specified otherwise.
For system management configuration tasks and examples, refer to the chapter entitled "Managing the System" in the Router Products Configuration Guide.
Use the buffers global configuration command to make adjustments to initial buffer pool settings and to the limits at which temporary buffers are created and destroyed. Use the no buffers command to return the buffers to their default size.
buffers {small | middle | big | large | huge} {permanent | max-free | min-free | initial} number| small | Small buffer size. |
| middle | Medium buffer size. |
| big | Big buffer size. |
| large | Large buffer size. |
| huge | Huge buffer size. |
| permanent | Number of permanent buffers that the system tries to allocate. Permanent buffers are normally not deallocated by the system. |
| max-free | Maximum number of free or unallocated buffers in a buffer pool. |
| min-free | Minimum number of free or unallocated buffers in a buffer pool. |
| initial | Number of additional temporary buffers that should be allocated when the system is reloaded. This can be used to ensure that the system has necessary buffers immediately after reloading in a high-traffic environment. |
| number | Number of buffers to be allocated. |
The default number of the buffers in a pool is determined by the hardware configuration and can be displayed with the EXEC show buffers command.
Global configuration
It is normally not necessary to adjust these parameters; do so only after consulting with technical support personnel. Improper settings could adversely impact system performance.
On the Cisco 4000, when building the receive rings for the serial and Ethernet interfaces, if a buffer request fails (that is, there isn't enough of that buffer size left in the pool), the interface is marked as down and the initialization is abandoned at that point. The interface will later initialize as more buffers are created to fill the demand. The configuration where this problem is most noticeable is the 1E4T configuration. The Serial 3 interface could take as long as 5 minutes before that interface would be usable.
However, buffer pool allocation is a user tunable parameter. The buffer pool to tune depends on the type of encapsulation used by the interfaces. Correspondingly, the ring size changes with the size of the buffer required. The mapping between buffer and ring size on the Cisco 4000 listed in Table 5-1.
| Maximum Transmission Unit (MTU) | Receive Ring Size |
|---|---|
| MTU < 1524 | 32 |
| 1524 < MTU < 5024 | 8 |
| 5024 < MTU < 18024 | 4 |
See the examples that follow for specific examples of allocating buffer sizes for the Cisco 4000.
In the following example, the system will try to keep at least 50 small buffers free:
buffers small min-free 50
On a Cisco 4000 1E4T box using HDLC encapsulation, there are five receive rings, each of 32 entries. The cache size is 32 buffers. The MTU for this sort of encapsulation is below 1524 bytes (the same as for Ethernet) which means that you must use buffers from the "big" pool. The basic number of "big" buffers required is (5 + 1) * 32 = 192. Adding a bit of "comfort" space, the following command can then be used:
buffers big permanent 200
This command increases the permanent buffer pool allocation for big buffers to 200.
On a Cisco 4000 6T box, using X.25 encapsulation, there are six receive rings, each with eight entries, plus a cache ring of eight entries. The MTU for this sort of encapsulation is below 5024 bytes but above 1524, so you must use buffers from the "large" pool. The basic number of "large" buffers required is (6 + 1) * 8 = 56. Adding a bit of "comfort" space, the following command can then be used:
buffers large permanent 60
This command increases the permanent buffer pool allocation for big buffers to 60.
A general guideline is to boot the box, check for whichever buffer pool is depleted, and increase that one. The above examples are just approximate figures for the various configurations.
buffers huge size
show buffers
Use the buffers huge size global configuration command to dynamically resize all huge buffers to the value you specify. Use the no buffers huge size command to restore the default buffer values.
buffers huge size number| number | Number of buffers to be allocated |
18024 buffers
Global configuration
Use only after consulting with technical support personnel. The buffer size cannot be lowered below the default.
In the following example, the system will resize huge buffers to 20000 bytes:
buffers huge size 20000
buffers
show buffers
To set the system calendar for a Cisco 7000 system or a Cisco 4500 system, use the calendar set EXEC command.
calendar set hh:mm:ss day month year| hh:mm:ss | Current time in hours (military format), minutes, and seconds |
| day | Current day (by date) in the month |
| month | Current month (by name) |
| year | Current year (no abbreviation) |
EXEC
Once you set the Cisco 7000 calendar or the Cisco 4500 calendar, the system clock will be automatically set when the system is restarted or when the clock read-calendar EXEC command is issued. The calendar maintains its accuracy, even after a power failure or system reboot has occurred. The time specified in this command is relative to the configured time zone.
In the following example, the system calendar is manually set to 1:32 p.m. on July 23, 1993:
calendar set 13:32:00 23 July 1993
clock read-calendar
clock set
clock summer-time
clock timezone
clock update-calendar
To configure the Cisco 7000 series or the Cisco 4500 as a time source for a network based on its calendar, use the clock calendar-valid global configuration command. Use the no form of this command to set the router so that the calendar is not an authoritative time source.
clock calendar-validThis command has no arguments or keywords.
Neither the Cisco 7000 nor the Cisco 4500 are not configured as a time source.
Global configuration
Use this command if no outside time source is available.
In the following example, the Cisco 7000 is configured as the time source for a network based on its calendar:
clock calendar-valid
A dagger (+) indicates that the command is documented in another chapter.
ntp master
vines time use-system +
To manually read the calendar into either the Cisco 7000 or the Cisco 4500 system clock, use the clock read-calendar EXEC command.
clock read-calendarThis command has no arguments or keywords.
EXEC
When either the Cisco 7000 series or the Cisco 4500 calendar is rebooted, the calendar is automatically read into the system clock. However, you may use this command to manually read the calendar setting into the system clock. This command is useful if the calendar set command has been used to change the setting of the calendar.
In the following example, the system clock is configured to set its date and time by the calendar setting:
clock read-calendar
calendar set
clock set
clock update-calendar
ntp update-calendar
To manually set the system clock, use the clock set EXEC command.
clock set hh:mm:ss day month year| hh:mm:ss | Current time in hours (military format), minutes, and seconds |
| day | Current day (by date) in the month |
| month | Current month (by name) |
| year | Current year (no abbreviation) |
EXEC
Generally, if the system is synchronized by a valid outside timing mechanism, such as an NTP or VINES clock source, or if you have a Cisco 7000 with calendar capability, you do not need to set the system clock. Use this command if no other time sources are available. The time specified in this command is relative to the configured time zone.
In the following example, the system clock is manually set to 1:32 p.m. on July 23, 1993:
clock set 13:32:00 23 July 1993
calendar set
clock read-calendar
clock summer-time
clock timezone
To configure the system to automatically switch to summer time (daylight savings time), use one of the formats of the clock summer-time configuration command. Use the no form of this command to configure the router not to automatically switch to summer time.
clock summer-time zone recurring [week day month hh:mm week day month hh:mm [offset]]| zone | Name of the time zone (PDT, ...) to be displayed when summer time is in effect |
| week | Week of the month (1 to 5 or last) |
| day | Day of the week (Sunday, Monday, ...) |
| date | Date of the month (1 to 31) |
| month | Month (January, February, ...) |
| year | Year (1993 to 2035) |
| hh:mm | Time (military format) in hours and minutes |
| offset | (Optional) Number of minutes to add during summer time (default is 60) |
Summer time is disabled. If clock summer-time zone recurring is specified without parameters, the summer time rules default to United States rules. Default of offset is 60.
Global configuration
Use this command if you want to automatically switch to summer time (for display purposes only). Use the recurring form of the command if the local summer time rules are of this form. Use the date form to specify a start and end date for summer time if you cannot use the first form.
In both forms of the command, the first part of the command specifies when summer time begins, and the second part specifies when it ends. All times are relative to the local time zone. The start time is relative to standard time. The end time is relative to summer time. If the starting month is after the ending month, the system assumes that you are in the Southern Hemisphere.
In the following example, summer time starts on the first Sunday in April at 02:00 and ends on the last Sunday in October at 02:00:
clock summer-time PDT recurring 1 Sunday April 2:00 last Sunday October 2:00
If you live in a place where summer time does not follow the pattern in the first example, you could set it to start on October 12, 1993 at 02:00, and end on April 28, 1994 at 02:00, with the following example:
clock summer-time date 12 October 1993 2:00 28 April 1994 2:00
calendar set
clock timezone
To set the time zone for display purposes, use the clock timezone global configuration command. To set the time to Coordinated Universal Time (UTC), use the no clock timezone command.
clock timezone zone hours [minutes]| zone | Name of the time zone to be displayed when standard time is in effect |
| hours | Hours offset from UTC |
| minutes | (Optional) Minutes offset from UTC |
UTC
Global configuration
The system internally keeps time in UTC, so this command is used only for display purposes and when the time is manually set.
In the following example, the timezone is set to Pacific Standard Time and is offset 8 hours behind UTC:
clock timezone PST -8
calendar set
clock set
clock summer-time
show clock
To set the Cisco 7000 or Cisco 4500 calendar from the system clock, use the clock update-calendar EXEC command.
clock update-calendarThis command has no arguments or keywords.
EXEC
If the system clock and calendar are not synchronized, and the system clock is more accurate, use this command to update the Cisco 7000 series or Cisco 4500 calendar to the correct date and time.
In the following example, the current time is copied from the system clock to the Cisco 7000 calendar:
clock update-calendar
clock read-calendar
ntp update-calendar
To assign a custom queue list to an interface, use the custom-queue-list interface configuration command. To remove a specific list or all list assignments, use the no form of the command.
custom-queue-list list| list | Number of the custom queue list you want to assign to the interface. An integer from 1 to 10. |
No custom queue list is assigned.
Interface configuration
Only one queue list can be assigned per interface. Use this command in place of the priority-list command (not in addition to it). Custom queuing allows a fairness not provided with priority queuing. With custom queuing, you can control the interfaces' available bandwidth when it is unable to accommodate the aggregate traffic enqueued. Associated with each output queue is a configurable byte count, which specifies how many bytes of data should be delivered from the current queue by the system before the system moves on to the next queue. When a particular queue is being processed, packets are sent until the number of bytes sent exceeds the queue byte count or until the queue is empty.
In the following example, custom queue list number 3 is assigned to interface serial 0:
interface serial 0
custom-queue-list 3
queue-list default
queue-list interface
queue-list protocol
queue-list queue byte-count
queue-list queue limit
queue-list stun
To specify what happens if the TACACS servers used by the enable command do not respond, use the enable last-resort global configuration command. The no enable last-resort global configuration command restores the default.
enable last-resort {password | succeed}| password | Allows you to enable by entering the privileged command level password. |
| succeed | Allows you to enable without further question. |
Default action is to fail.
Global configuration
In the following example, if the TACACS servers do not respond to the enable command, the user can enable by entering the privileged level password:
enable last-resort password
A dagger (+) indicates that the command is documented in another chapter.
enable +
To assign a password for the privileged command level, use the enable password global configuration command. The commands enable password and enable-password are synonymous.
enable password password| password | Case-sensitive character string that specifies the line password prompted for in response to the EXEC command enable. The first character cannot be a number. The string can contain any alphanumeric characters, including spaces, up to 80 characters. You cannot specify the password in the format number-space-anything. The space after the number causes problems. |
No password is assigned.
Global configuration
When you use the enable command at the console terminal, the EXEC will not prompt you for a password if the privileged mode password is not set. Additionally, if the enable password is not set and the line 0 (console line) password is not set, then it is only possible to enter privileged mode on the console terminal. This feature allows you to use physical security rather than passwords to protect privileged mode if you choose.
If the enable password is not set and the line 0 (console) password is set, it is possible to enter privileged command mode in two ways: either without having to enter a password at the console terminal, or if you are using any other line, by entering the console line password when prompted.
This example sets the password secretword for the privileged command level on all lines, including the console:
enable password secretword
A dagger (+) indicates that the command is documented in another chapter.
login +
login tacacs +
password +
To specify an additional layer of security over the enable password command, use the enable secret command. Use the no form of the command to turn off the enable secret function.
enable secret password| password | The enable secret password. This password should be different from the password created with the enable password command for additional security. |
Disabled
Global configuration
The enable secret command is used in conjunction with the enable password command to provide an additional layer of security over the enable password. This process provides better security in two ways: first by enforcing the use of an additional password; second, by storing this second password using a nonreversible cryptographic function. This encryption method is especially useful in environments where the password crosses a network or is stored on a TFTP server.
If you use the same password for enable password and enable secret, you will receive an error message warning you that this practice is not recommended. The system will prompt you again for a password. You can reenter the password you use for enable password, and the system will accept it the second time. But if you do, you undermine the additional security that the enable secret command provides.
The following example specifies an enable secret password of gobbledeegook:
enable secret gobbledeegook
After you specify an enable secret password, users must enter this password to gain access. Any passwords set through enable password will no longer work.
Password: gobbledeegook
To enable use of the TACACS to determine whether a user can access the privileged command level, use the enable use-tacacs global configuration command. Use the no enable use-tacacs command to disable TACACS verification.
enable use-tacacsThis command has no arguments or keywords.
Disabled
Global configuration
When you add this command to the configuration file, the EXEC enable command prompts for a new username and password pair. This pair is then passed to the TACACS server for authentication. If you are using the Extended TACACS, it also will pass any already-existing UNIX user identification code to the server.
 | Caution If you use the enable use-tacacs command, you must also use the tacacs-server authenticate enable command, or else you will be locked out of the router. |
The following example sets TACACS verification on the privileged EXEC-level login sequence:
enable use-tacacs
tacacs-server authenticate enable
tacacs-server authenticate enable
To specify or modify the host name for the network server, use the hostname global configuration command. The host name is used in prompts and default configuration filenames. The setup command facility also prompts for a host name at startup.
hostname name| name | New host name for the network server; the name is case sensitive. |
The factory-assigned default host name is router.
Global configuration
The order of display at startup is banner Message-of-the-Day (MOTD), then login and password prompts, then EXEC banner.
The following example changes the host name to sandbox:
hostname sandbox
To log messages to a syslog server host, use the logging global configuration command. The no logging command deletes the syslog server with the specified address from the list of syslogs.
logging host| host | Name or IP address of the host to be used as a syslog server |
No messages are logged to a syslog server host.
Global configuration
This command identifies a syslog server host to receive logging messages. By issuing this command more than once, you build a list of syslog servers that receive logging messages.
The following example logs messages to a host named johnson:
logging johnson
logging trap
service timestamps
To log messages to an internal buffer, use the logging buffered global configuration command. The no logging buffered command cancels the use of the buffer and writes messages to the console terminal, which is the default.
logging bufferedThis command has no arguments or keywords.
The router displays all messages to the console terminal.
Global configuration
This command copies logging messages to an internal buffer instead of writing them to the console terminal. The buffer is circular in nature, so newer messages overwrite older messages.
To display the messages that are logged in the buffer, use the EXEC command show logging. The first message displayed is the oldest message in the buffer.
The following example illustrates how to enable logging to an internal buffer:
logging buffered
To limit messages logged to the console based on severity, use the logging console global configuration command. The no logging console command disables logging to the console terminal.
logging console level| level | Limits the logging of messages displayed on the console terminal to the named level. See Table 5-2 for a list of the level keywords. |
debugging
Global configuration
Specifying a level causes messages at that level and numerically lower levels to be displayed at the console terminal.
The EXEC command show logging displays the addresses and levels associated with the current logging setup, as well as any other logging statistics.
| Level Name | Level | Description | Syslog Definition |
|---|---|---|---|
| emergencies | 0 | System unusable | LOG_EMERG |
| alerts | 1 | Immediate action needed | LOG_ALERT |
| critical | 2 | Critical conditions | LOG_CRIT |
| errors | 3 | Error conditions | LOG_ERR |
| warnings | 4 | Warning conditions | LOG_WARNING |
| notifications | 5 | Normal but significant condition | LOG_NOTICE |
| informational | 6 | Informational messages only | LOG_INFO |
| debugging | 7 | Debugging messages | LOG_DEBUG |
The following example changes the level of messages displayed to the console terminal to alerts, which means alerts and emergencies are displayed:
logging console alerts
logging facility
To configure the syslog facility in which error messages are sent, use the logging facility global configuration command. To revert to the default of local7, use the no logging facility global configuration command.
logging facility facility-type| facility-type | See Table 5-3 for the facility-type keywords. |
local7
Global configuration
| Keyword | Description |
|---|---|
| auth | Authorization system |
| cron | Cron facility |
| daemon | System daemon |
| kern | Kernel |
| local0-7 | Reserved for locally defined messages |
| lpr | Line printer system |
| Mail system | |
| news | USENET news |
| sys9 | System use |
| sys10 | System use |
| sys11 | System use |
| sys12 | System use |
| sys13 | System use |
| sys14 | System use |
| syslog | System log |
| user | User process |
| uucp | UNIX-to-UNIX copy system |
The following example configures the syslog facility to Kernel:
logging facility kern
logging console
To limit messages logged to the terminal lines (monitors) based on severity, use the logging monitor global configuration command. This command limits the logging messages displayed on terminal lines other than the console line to messages with a level at or above level. The no logging monitor command disables logging to terminal lines other than the console line.
logging monitor level| level | One of the level keywords listed in Table 5-2 |
debugging
Global configuration
Specifying a level causes messages at that level and numerically lower levels to be displayed to the monitor.
The following example specifies that only messages of the levels errors, critical, alerts, and emergencies be displayed on terminals:
logging monitor errors
A dagger (+) indicates that the command is documented in another chapter.
terminal monitor +
To control logging of error messages, use the logging on global configuration command. This command enables or disables message logging to all destinations except the console terminal. The no logging on command enables logging to the console terminal only.
logging onThis command has no arguments or keywords.
The router logs messages to the console terminal.
Global configuration
The following example shows how to direct error messages to the console terminal only:
no logging on
| level severity-level-number | (Optional) Specifies the message severity level. Messages with a severity level equal to or higher than this value are printed asynchronously. When specifying a severity level number, consider that for the logging system, low numbers indicate greater severity and high numbers indicate lesser severity. The default value is 2. |
| all | (Optional) Specifies that all messages are printed asynchronously, regardless of the severity level. |
| limit number-of-buffers | (Optional) Specifies the number of buffers to be queued for the terminal after which new messages are dropped. The default value is 20. |
This feature is turned off by default.
If you do not specify a severity level, the default value of 2 is assumed.
If you do not specify the maximum number of buffers to be queued, the default value of 20 is assumed.
Line configuration
When synchronous logging of unsolicited messages and debug output is turned on, unsolicited router output is displayed on the console or printed after solicited router output is displayed or printed. Unsolicited messages and debug output is displayed on the console after the prompt for user input is returned. This is to keep unsolicited messages and debug output from being interspersed with solicited router output and prompts. After the unsolicited messages are displayed, the console displays the user prompt again.
When specifying a severity level number, consider that for the logging system, low numbers indicate greater severity and high numbers indicate lesser severity.
When a terminal line's message-queue limit is reached, new messages are dropped from the line, although these messages might be displayed on other lines. If messages are dropped, the notice "%SYS-3-MSGLOST number-of-messages due to overflow" follows any messages that are displayed. This notice is displayed only on the terminal that lost the messages. It is not sent to any other lines, any logging servers, or the logging buffer.
| Caution By configuring abnormally large message-queue limits and setting the terminal to "terminal monitor" on a terminal that is accessible to intruders, you expose yourself to "denial of service" attacks. An intruder could carry out the attack by putting the terminal in synchronous output mode, making a Telnet connection to a remote host, and leaving the connection idle. This could cause large numbers of messages to be generated and queued, and these messages would consume all available RAM. Although unlikely to occur, you should guard against this type of attack through proper configuration. |
The following example identifies line 4 and enables synchronous logging for line 4 with a severity level of 6. Then the example identifies another line, line 2, and enables synchronous logging for line 2 with a severity level of 7 and specifies a maximum number of buffers to be 70000:
line 4
logging synchronous level 6
line 2
logging synchronous level 7 limit 70000
A dagger (+) indicates that the command is documented in another chapter.
line+
To limit messages logged to the syslog servers based on severity, use the logging trap global configuration command. The command limits the logging of error messages sent to syslog servers to only those messages at the specified level. The no logging trap command disables logging to syslog servers.
logging trap level| level | One of the level keywords listed in Table 5-2 |
informational
Global configuration
The EXEC command show logging displays the addresses and levels associated with the current logging setup. The command output also includes ancillary statistics.
Table 5-2 lists the syslog definitions that correspond to the debugging message levels. Additionally, there are four categories of messages generated by the software, as follows:
Use the logging and logging trap commands to send messages to a UNIX syslog server.
The following example logs messages to a host named johnson:
logging johnson
logging trap notifications
logging
To control access to the system's Network Time Protocol (NTP) services, use the ntp access-group global configuration command. To remove access control to the system's NTP services, use the no ntp access-group command.
ntp access-group {query-only | serve-only | serve | peer} access-list-number| query-only | Allows only NTP control queries. See RFC 1305 (NTP version 3). |
| serve-only | Allows only time requests. |
| serve | Allows time requests and NTP control queries, but does not allow the system to synchronize to the remote system. |
| peer | Allows time requests and NTP control queries and allows the system to synchronize to the remote system. |
| access-list-number | Number (1 to 99) of a standard IP access list. |
No access control (full access granted to all systems)
Global configuration
The access group options are scanned in the following order from least restrictive to most restrictive:
Access is granted for the first match that is found. If no access groups are specified, all access is granted to all sources. If any access groups are specified, only the specified access is granted. This facility provides minimal security for the time services of the system. However, it can be circumvented by a determined programmer. If tighter security is desired, use the NTP authentication facility.
In the following example, the system is configured to allow itself to be synchronized by a peer from access list 99. However, the system restricts access to allow only time requests from access list 42.
ntp access-group peer 99
ntp access-group serve-only 42
A dagger (+) indicates that the command is documented in another chapter.
access-list +
To enable Network Time Protocol (NTP) authentication, use the ntp authenticate global configuration command. Use the no form of this command to disable the feature.
ntp authenticateThis command has no keywords or arguments.
No authentication
Global configuration
Use this command if you want authentication. If this command is specified, the system will not synchronize to a system unless it carries one of the authentication keys specified in the ntp trusted-key command.
The following example enables NTP authentication:
ntp authenticate
ntp authentication-key
ntp trusted-key
To define an authentication key for Network Time Protocol (NTP) , use the ntp authentication-key global configuration command. Use the no form of this command to remove the authentication key for NTP.
ntp authentication-key number md5 value| number | Key number (1 to 4294967295) |
| value | Key value (an arbitrary string of up to eight characters) |
No authentication key is defined for NTP.
Global configuration
Use this command to define authentication keys for use with other NTP commands in order to provide a higher degree of security.
The following example sets authentication key 10 to aNiceKey:
ntp authentication-key 10 md5 aNiceKey
ntp authenticate
ntp peer
ntp server
ntp trusted-key
To specify that a specific interface should send Network Time Protocol (NTP) broadcast packets, use the ntp broadcast interface configuration command. Use the no form of the command to disable this capability.
ntp broadcast [version number]| version number | (Optional) Number from 1 to 3 indicating the NTP version |
Disabled
Interface configuration
In the following example, interface Ethernet0 is configured to send NTP version 2 packets:
interface ethernet0
ntp broadcast version 2
ntp broadcast client
ntp broadcastdelay
To allow the system to receive NTP broadcast packets on an interface, use the ntp broadcast client command. Use the no form of the command to disable this capability.
ntp broadcast clientThis command has no arguments or keywords.
Disabled
Interface configuration
Use this command to allow the system to listen to broadcast packets on an interface-by-interface basis.
In the following example, the router synchronizes to NTP packets broadcasted on interface Ethernet1:
interface ethernet1
ntp broadcast client
ntp broadcast
ntp broadcastdelay
To set the estimated round-trip delay between the router and a Network Time Protocol (NTP) broadcast server, use the ntp broadcastdelay global configuration command. Use the no form of this command to revert to the default value.
ntp broadcastdelay microseconds| microseconds | Estimated round-trip time (in microseconds) for NTP broadcasts. The range is from 1 to 999999. |
3000 microseconds
Global configuration
Use this command when the router is configured as a broadcast client and the round-trip delay on the network is other than 3000 microseconds.
In the following example, the estimated round-trip delay between the router and the broadcast client is set to 5000 microseconds:
ntp broadcastdelay 5000
ntp broadcast
ntp broadcast client
Do not enter this command; it is documented for informational purposes only. The system automatically generates this command as Network Time Protocol (NTP) determines the clock error and compensates.
As NTP compensates for the error in the system clock, it keeps track of the correction factor for this error. The system automatically saves this value into the system configuration using the ntp clock-period global configuration command. The system uses the no form of this command to revert to the default.
ntp clock-period value| value | Amount to add to the system clock for each clock hardware tick (in units of 2-32 seconds). |
17179869 (4 milliseconds)
Global configuration
If a write memory command is entered to save the configuration to NVRAM, this command will automatically be added to the configuration. It is a good idea to perform this task after NTP has been running for a week or so; this will help NTP synchronize more quickly if the system is restarted.
To prevent an interface from receiving Network TIme Protocol (NTP) packets, use the ntp disable interface configuration command. To enable receipt of NTP packets on an interface, use the no ntp disable command.
ntp disableThis command has no arguments or keywords.
Enabled
Interface configuration
This command provides a simple method of access control.
In the following example, interface Ethernet 0 is prevented from receiving NTP packets:
interface ethernet0
ntp disable
To configure the router as a Network Time Protocol (NTP) master clock to which peers synchronize themselves when an external NTP source is not available, use the ntp master global configuration command. To disable the master clock function, use the no ntp master command.
ntp master [stratum]| stratum | (Optional) Number from 1 to 15. Indicates the NTP stratum number that the system will claim. |
By default, the master clock function is disabled. When enabled, the default stratum is 8.
Global configuration
Since our implementation of NTP does not support directly attached radio or atomic clocks, the router is normally synchronized, directly or indirectly, to an external system that has such a clock. In a network without Internet connectivity, such a time source may not be available. The ntp master command is used in such cases.
If the system has ntp master configured, and it cannot reach any clock with a lower stratum number, the system will claim to be synchronized at the configured stratum number, and other systems will be willing to synchronize to it via NTP.
| Caution Use this command with extreme caution. It is very easy to override valid time sources using this command, especially if a low stratum number is configured. Configuring multiple machines in the same network with the ntp master command can cause instability in timekeeping if the machines do not agree on the time. |
In the following example, the router is configured as an NTP master clock to which peers may synchronize:
ntp master 10
clock calendar-valid
To configure the router's system clock to synchronize a peer or to be synchronized by a peer, use the
ntp peer global configuration command. To disable this capability, use the no ntp peer command.
| ip-address | IP address of the peer providing, or being provided, the clock synchronization. |
| version | (Optional) Defines the Network Time Protocol (NTP) version number. |
| number | (Optional) NTP version number (1 to 3). |
| key | (Optional) Defines the authentication key. |
| keyid | (Optional) Authentication key to use when sending packets to this peer. |
| source | (Optional) Names the interface. |
| interface | (Optional) Name of the interface from which to pick the IP source address. |
| prefer | (Optional) Makes this peer the preferred peer that provides synchronization. |
No peers are configured by default. If a peer is configured, the default NTP version number is 3, no authentication key is used, and the source IP address is taken from the outgoing interface.
Global configuration
Use this command if you want to allow this machine to synchronize with the peer, or vice versa. Using the prefer keyword will reduce switching back and forth between peers.
If you are using the default version of 3 and NTP synchronization does not occur, try using NTP version number 2. Many NTP servers on the Internet run version 2.
In the following example, the router is configured to allow its system clock to be synchronized with the clock of the peer (or vice versa) at IP address 131.108.22.33 using NTP version 2. The source IP address will be the address of Ethernet 0.
ntp peer 131.108.22.33 version 2 source Ethernet 0
ntp authentication-key
ntp server
ntp source
To allow the router's system clock to be synchronized by a time server, use the ntp server global configuration command. To disable this capability, use the no ntp server command.
ntp server ip-address [version number] [key keyid] [source interface] [prefer]| ip-address | IP address of the time server providing the clock synchronization. |
| version | (Optional) Defines the Network Time Protocol (NTP) version number. |
| number | (Optional) NTP version number (1 to 3). |
| key | (Optional) Defines the authentication key. |
| keyid | (Optional) Authentication key to use when sending packets to this peer. |
| source | (Optional) Identifies the interface from which to pick the IP source address. |
| interface | (Optional) Name of the interface from which to pick the IP source address. |
| prefer | (Optional) Makes this server the preferred server that provides synchronization. |
No peers are configured by default. If a peer is configured, the default NTP version number is 3, no authentication key is used, and the source IP address is taken from the outgoing interface.
Global configuration
Use this command if you want to allow this machine to synchronize with the specified server. The server will not synchronize to this machine.
Using the prefer keyword will reduce switching back and forth between servers.
If you are using the default version of 3 and NTP synchronization does not occur, try using NTP version number 2. Many NTP servers on the Internet run version 2.
In the following example, the router is configured to allow its system clock to be synchronized with the clock of the peer at IP address 128.108.22.44 using NTP version 2:
ntp server 128.108.22.44 version 2
ntp authentication-key
ntp peer
ntp source
To use a particular source address in Network Time Protocol (NTP) packets, use the ntp source global configuration command. Use the no form of this command to remove the specified source address.
ntp source interface| interface | Any valid system interface name |
Source address is determined by the outgoing interface.
Global configuration
Use this command when you want to use a particular source IP address for all NTP packets. The address is taken from the named interface. This command is useful if the address on an interface cannot be used as the destination for reply packets. If the source keyword is present on an ntp server or ntp peer command, that value overrides the global value.
In the following example, the router is configured to use the IP address of Ethernet 0 as the source address of all outgoing NTP packets:
ntp source ethernet 0
ntp peer
ntp server
If you want to authenticate the identity of a system to which Network Time Protocol (NTP) will synchronize, use the ntp trusted-key global configuration command. Use the no form of this command to disable authentication of the identity of the system.
ntp trusted-key key-number| key-number | Key number of authentication key to be trusted |
Disabled
Global configuration
If authentication is enabled, use this command to define one or more key numbers (corresponding to the keys defined with the ntp authentication-key command) that a peer NTP system must provide in its NTP packets, in order for this system to synchronize to it. This provides protection against accidentally synchronizing the system to a system that is not trusted, since the other system must know the correct authentication key.
In the following example, the system is configured to synchronize only to systems providing authentication key 42 in its NTP packets:
ntp authenticate
ntp authentication-key 42 md5 aNiceKey
ntp trusted-key 42
ntp authenticate
ntp authentication-key
To periodically update the Cisco 7000 calendar from Network Time Protocol (NTP), use the ntp update-calendar global configuration command. Use the no form of this command to disable this feature.
ntp update-calendarThis command has no arguments or keywords.
The Cisco 7000 calendar is not updated.
Global configuration
If a Cisco 7000 is synchronized to an outside time source via NTP, it is a good idea to periodically update the calendar with the time learned from NTP. Otherwise, the calendar will tend to gradually lose or gain time. The calendar will be updated only if NTP has synchronized to an authoritative time server.
In the following example, the system is configured to periodically update the calendar from the system clock:
ntp update-calendar
clock read-calendar
clock update-calendar
Use the ping (packet internet groper) user EXEC command to diagnose basic network connectivity on AppleTalk, CLNS, IP, Novell, Apollo, VINES, DECnet, or XNS networks.
ping [protocol] {host | address}| protocol | (Optional) Protocol keyword, one of apollo, appletalk, clns, decnet, ip, ipx, vines, or xns |
| host | Host name of system to ping |
| address | Address of system to ping |
EXEC
The user-level ping feature provides a basic ping facility for users who do not have system privileges. This feature allows the router to perform the simple default ping functionality for a number of protocols. Only the nonverbose form of the ping command is supported for user-level pings.
If the system cannot map an address for a host name, it will return an "%Unrecognized host or address" error message.
To abort a ping session, type the escape sequence (by default, Ctrl-^ X, which is done by simultaneously pressing the Ctrl, Shift, and 6 keys, letting go, then pressing the X key).
Table 5-4 describes the test characters that the ping facility sends.
| Char | Meaning |
|---|---|
| ! | Each exclamation point indicates receipt of a reply. |
| . | Each period indicates the network server timed out while waiting for a reply. |
| U | A destination unreachable error PDU was received. |
| C | A congestion experienced packet was received. |
| I | User interrupted test. |
| ? | Unknown packet type. |
| & | Packet lifetime exceeded. |
The following display shows sample ping output when you ping the IP host named donald:
Router> ping donald
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.31.7.27, timeout is 2 seconds:
!!!!!
Success rate is 100 percent, round-trip min/avg/max = 1/3/4 ms
ping (privileged)
Use the ping (packet internet groper) privileged EXEC command to diagnose basic network connectivity on Apollo, AppleTalk, CLNS, DECnet, IP, Novell IPX, VINES, or XNS networks.
ping [protocol] {host | address}| protocol | (Optional) Protocol keyword, one of apollo, appletalk, clns, decnet, ip, ipx, vines, or xns |
| host | Host name of system to ping |
| address | Address of system to ping |
Privileged EXEC
The ping program sends an echo request packet to an address, then awaits a reply. Ping output can help you evaluate path-to-host reliability, delays over the path, and whether the host can be reached or is functioning.
To abort a ping session, type the escape sequence (by default, Ctrl-^ X, which is done by simultaneously pressing the Ctrl, Shift, and 6 keys, letting go, then pressing the X key).
Table 5-5 describes the test characters that the ping facility sends.
| Char | Meaning |
|---|---|
| ! | Each exclamation point indicates receipt of a reply. |
| . | Each period indicates the network server timed out while waiting for a reply. |
| U | A destination unreachable error PDU was received. |
| C | A congestion experienced packet was received. |
| I | User interrupted test. |
| ? | Unknown packet type. |
| & | Packet lifetime exceeded. |
After you enter the ping command in privileged mode, the system prompts for one of the following keywords: appletalk, clns, ip, novell, apollo, vines, decnet, or xns. The default protocol is IP.
If you enter a host name or address on the same line as the ping command, the default action is taken as appropriate for the protocol type of that name or address.
While the precise dialog varies somewhat from protocol to protocol, all are similar to the ping session using default values shown in the following display.
Router# ping
Protocol [ip]:
Target IP address: 192.31.7.27
Repeat count [5]:
Datagram size [100]:
Timeout in seconds [2]:
Extended commands [n]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.31.7.27, timeout is 2 seconds:
!!!!!
Success rate is 100 percent, round-trip min/avg/max = 1/2/4 ms
Table 5-6 describes the default ping fields shown in the display.
ping (user)
To enable TACACS for PPP authentication, use the ppp use-tacacs interface configuration command. Use the no form of the command to disable TACACS for PPP authentication.
ppp use-tacacs [single-line]| single-line | (Optional) Accept the username and password in the username field. This option applies only when using CHAP authentication. |
TACACS is not used for PPP authentication.
Interface configuration
This is a per-interface command. Use this command only when you have set up an extended TACACS server. This command requires the new extended TACACS server.
When CHAP authentication is being used, the ppp use-tacacs command with the single-line option specifies that if a username and password are specified in the username, separated by an asterix (*), then a standard tacacs login query is performed using that username and password. If the username does not contain an asterix, then normal CHAP authentication is performed using TACACS.
This feature is useful when integrating TACACS with other authentication systems that require a clear-text version of the user's password. Such systems include one-time password systems, token card systems, kerberos, and others.
| **before**Normal CHAP authentications prevent the clear-text password from being transmitted over the link. When you use the single-line option, passwords will cross the link in the clear.@@before@@ | Warning **after**Normal CHAP authentications prevent the clear-text password from being transmitted over the link. When you use the single-line option, passwords will cross the link in the clear.@@after@@ |
If the username and password are contained in the CHAP password, then the CHAP secret is not used by the Cisco system. Because most PPP clients will require that a secret be specified, you can use any arbitrary string; the Cisco system will ignore it.
In the following example, asynchronous serial interface 1 is configured to use TACACS for CHAP authentication.
interface async 1
ppp authentication chap
ppp use-tacacs
In the following example, asynchronous serial interface 1 is configured to use TACACS for PAP authentication.
interface async 1
ppp authentication pap
ppp use-tacacs
A dagger (+) indicates that the command is documented in another chapter.
ppp authentication chap+
ppp authentication pap+
tacacs-server extended +
tacacs-server host+
To assign the specified priority list to an interface, use the priority-group interface configuration command. Use the no priority-group command to remove the specified priority-group assignment.
priority-group list| list | Priority list number assigned to the interface |
None
Interface configuration
Only one list can be assigned per interface. Priority output queueing provides a mechanism to prioritize packets transmitted on an interface.
The following example causes packets on interface serial 0 to be classified by priority list 1:
interface serial 0
priority-group 1
priority-list
priority-list interface
priority-list queue-limit
priority-list stun
To assign a priority queue for those packets that do not match any other rule in the priority list, use the priority-list default global configuration command. Use the no priority-list default command to return to the default or assign normal as the default.
priority-list list-number default {high | medium | normal | low }| list-number | Arbitrary integer between 1 and 10 that identifies the priority list selected by the user |
| high | medium | normal | low | Priority queue level |
The normal queue is assumed if you use the no form of the command.
Global configuration
The following example sets the priority queue for those packets that do not match any other rule in the priority list to a low priority:
priority-list 1 default low
priority-group
show queueing
To establish queuing priorities on packets entering from a given interface, use the priority-list interface global configuration command. Use the no priority-list command with the appropriate arguments to remove an entry from the list.
priority-list list-number interface interface-type interface-number {high | medium || list-number | Arbitrary integer between 1 and 10 that identifies the priority list selected by the user. |
| interface-type | Specifies the name of the interface. |
| interface-number | Number of the specified interface. |
| high | medium | normal | low | Priority queue level. |
No queuing priorities are established.
Global configuration
The following example sets any packet type entering on interface Ethernet 0 to a medium priority:
priority-list 3 interface ethernet 0 medium
priority-group
show queueing
To establish queuing priorities based upon the protocol type, use the priority-list protocol global configuration command. Use the no priority-list protocol command with the appropriate list number to remove an entry from the list.
priority-list list -number protocol protocol-name {high | medium | normal | low}| list-number | Arbitrary integer between 1 and 10 that identifies the priority list selected by the user. |
| protocol-name | Specifies the protocol type: aarp, arp, apollo, appletalk, bridge (transparent), clns, clns_es, clns_is, compressedtcp, cmns, decnet, decnet_node, decnet_router-l1, decnet_router-l2, ip, ipx, pad, rsrb, stun, vines, xns, and x25. |
| high | medium | normal | low | Priority queue level. |
| queue-keyword keyword-value | Possible keywords are fragments, gt, lt, list, tcp, and udp. See Table 5-7. |
No queuing priorities are established.
Global configuration
When using multiple rules for a single protocol, remember that the system reads the priority settings in order of appearance. When classifying a packet, the system searches the list of rules specified by priority-list commands for a matching protocol type. When a match is found, the packet is assigned to the appropriate queue. The list is searched in the order it is specified, and the first matching rule terminates the search.
The decnet_router-l1 keyword refers to the multicast address for all level-1 routers, which are intra-area routers, and the decnet_router-l2 keyword refers to all level 2 routers, which are interarea routers.
Use Table 5-7, Table 5-8, and Table 5-9 to configure the queuing priorities for your system.
| Option | Description |
|---|---|
| fragments | Assigns the priority level defined to fragmented IP packets (for use with IP protocol only). More specifically, IP packets whose fragment offset field is nonzero are matched by this command. The initial fragment of a fragmented IP packet has a fragment offset of zero, so such packets are not matched by this command.
Note: Packets with a nonzero fragment offset do not contain TCP or UDP headers, so other instances of this command that use the tcp or udp keyword will always fail to match such packets. |
| gt byte-count | Specifies a greater-than count. The priority level assigned goes into effect when a packet exceeds the value entered for the argument byte-count. The size of the packet must also include additional bytes due to MAC encapsulation on the outgoing interface. |
| lt byte-count | Specifies a less-than count. The priority level assigned goes into effect when a packet size is less than the value entered for byte-count. The size of the packet must also include additional bytes due to MAC encapsulation on the outgoing interface. |
| list list-number | Assigns traffic priorities according to a specified list when used with Appletalk, bridging, IP, IPX, VINES, or XNS. The list-number argument is the access list number as specified by the access-list global configuration command for the specified protocol-name. For example, if the protocol is AppleTalk, list-number should be a valid AppleTalk access list number. |
| tcp port | Assigns the priority level defined to TCP segments originating from or destined to a specified port (for use with the IP protocol only). Table 5-8 lists common TCP services and their port numbers. |
| udp port | Assigns the priority level defined to UDP packets originating from or destined to the specified port (for use with the IP protocol only). Table 5-9 lists common UDP services and their port numbers. |
| Service | Port |
|---|---|
| Telnet | 23 |
| SMTP | 25 |
| Service | Port |
|---|---|
| TFTP | 69 |
| NFS | 2049 |
| SNMP | 161 |
| RPC | 111 |
| DNS | 53 |
Use the no priority-list global configuration command followed by the appropriate list-number argument and the protocol keyword to remove a priority list entry assigned by protocol type.
The following example assigns 1 as the arbitrary priority list number, specifies DECnet as the protocol type, and assigns a high-priority level to the DECnet packets transmitted on this interface:
priority-list 1 protocol decnet high
The following example assigns a medium-priority level to every DECnet packet with a size greater than 200 bytes:
priority-list 2 protocol decnet medium gt 200
The following example assigns a medium-priority level to every DECnet packet with a size less than 200 bytes:
priority-list 4 protocol decnet medium lt 200
The following example assigns a high-priority level to traffic that matches IP access list 10:
priority-list 1 protocol ip high list 10
The following example assigns a medium-priority level to Telnet packets:
priority-list 4 protocol ip medium tcp 23
The following example assigns a medium-priority level to UDP Domain Name service packets:
priority-list 4 protocol ip medium udp 53
The following example assigns a high-priority level to traffic that matches Ethernet type code access list 201:
priority-list 1 protocol bridge high list 201
priority-group
show queueing
To specify the maximum number of packets that can be waiting in each of the priority queues, use the priority-list queue-limit global configuration command.The no priority-list queue-limit command selects the normal queue.
priority-list list-number queue-limit high-limit medium-limit normal-limit low-limit| list-number | Arbitrary integer between 1 and 10 that identifies the priority list selected by the user. |
| high-limit medium-limit normal-limit low-limit | Priority queue maximum length. A value of 0 for any of the four arguments means that the queue can be of unlimited size for that particular queue. |
The default queue limit arguments are listed in Table 5-10.
| Priority Queue Argument | Packet Limits |
|---|---|
| high-limit | 20 |
| medium-limit | 40 |
| normal-limit | 60 |
| low-limit | 80 |
Global configuration
If a priority queue overflows, excess packets are discarded and quench messages can be sent, if appropriate, for the protocol.
The following example sets the maximum packets in the priority queue to 10:
priority-list 2 queue-limit 10 40 60 80
priority-group
show queueing
To establish queuing priorities based on the address of the serial link on a STUN connection, use the priority-list stun global configuration command. Use the no priority-list stun command with the appropriate arguments to remove an entry from the list.
priority-list list-number stun {high | medium | normal | low} address group-number address| list-number | Arbitrary integer between 1 and 10 that identifies the priority list selected by the user. |
| high | medium | normal | low | Priority queue level. |
| address | Required keyword. |
| group-number | Group number used in the stun group command. |
| address-number | Address of the serial link. The format of the address is either a 1-byte hex value (for example, C1) for an SDLC link or one that is specified by the stun schema global configuration command. |
No queuing priorities are established.
Global configuration
The following example illustrates how to prioritize STUN traffic over IP. STUN uses a special serial line protocol called STUN for the simple serial encapsulation and TCP port 1994 for the TCP encapsulation. The example assigns the same priority to STUN traffic over a serial link.
priority-list 4 ip high tcp 1994
priority-list 4 stun high address 3 C1
A dagger (+) indicates that the command is documented in another chapter.
priority-group
show queueing
stun schema +
To customize the router prompt, use the prompt global configuration command. To revert to the default router prompt, use the no form of this command.
prompt string| string | Router prompt. It can consist of all printing characters and the escape sequences listed in Table 5-11 in the "Usage Guidelines" section. |
The default router prompt is either Router or the router name defined with the hostname global configuration command, followed by an angle bracket (>) for EXEC mode or a pound sign (#) for privileged EXEC mode.
Global configuration
You can include escape sequences when specifying the router prompt. All escape sequences are preceded by a %. Table 5-11 lists the valid escape sequences.
| Escape Sequence | Interpretation |
|---|---|
| %h | Router's host name. This is either Router or the name defined with the hostname global configuration command. |
| %n | TTY number of the EXEC user. |
| %p | Prompt character itself. It is either an angle bracket (>) for EXEC mode or a pound sign (#) for privileged EXEC mode. |
| %s | Space. |
| %t | Tab. |
| %% | % |
Specifying the command prompt %h has the same effect as issuing the no prompt command.
The following example changes the EXEC prompt to include the TTY number, followed by the router name and a space:
prompt TTY%n@%h%s%p
The following are examples of user and privileged EXEC prompts that result from the previous command:
TTY17@Router1 >
TTY17SRouter1 #
hostname
To assign a priority queue for those packets that do not match any other rule in the queue list, use the queue-list default global configuration command. To restore the default value, use the
no queue-list default command.
| list-number | Number of the queue list. An integer from 1 to 10. |
| queue-number | Number of the queue. An integer from 1 to 10. |
Queue number 1
Global configuration
Queue number 0 is a system queue. It is emptied before any of the other queues are processed. The system enqueues high-priority packets, such as keepalives, to this queue.
In the following example, the default queue for list 10 is set to queue number 2:
queue-list 10 default 2
A dagger (+) indicates that the command is documented in another chapter.
custom-queue-list +
show queueing
To establish queuing priorities on packets entering on an interface, use the queue-list interface global configuration command. To remove an entry from the list, use the no form of the command.
queue-list list-number interface interface-type interface-number queue-number| list-number | Number of the queue list. An integer from 1 to 10. |
| interface-type | Required argument that specifies the name of the interface. |
| interface-number | Number of the specified interface. |
| queue-number | Number of the queue. An integer from 1 to 10. |
No queuing priorities are established.
Global configuration
In the following example, queue list 4 established queuing priorities for packets entering on interface tunnel 3. The queue number assigned is 10.
queue-list 4 interface tunnel 3 10
A dagger (+) indicates that the command is documented in another chapter.
custom-queue-list +
show queueing
To establish queuing priority based upon the protocol type, use the queue-list protocol global configuration command. Use the no queue-list protocol command with the appropriate list number to remove an entry from the list.
queue-list list-number protocol protocol-name queue-number queue-keyword keyword-value| list-number | Number of the queue list. An integer from 1 to 10. |
| protocol-name | Required argument that specifies the protocol type: aarp, arp, apollo, appletalk, bridge (transparent), clns, clns_es, clns_is, compressedtcp, cmns, decnet, decnet_node, decnet_routerl1, decnet_routerl2, ip, ipx, pad, rsrb, stun, vines, xns, and x25. |
| queue-number | Number of the queue. An integer from 1 to 10. |
| queue-keyword keyword-value | Possible keywords are gt, lt, list, tcp, and udp. See Table 5-7. |
No queuing priorities are established.
Global configuration
When classifying a packet, the system searches the list of rules specified by queue-list commands for a matching protocol type. When a match is found, the packet is assigned to the appropriate queue. The list is searched in the order it is specified, and the first matching rule terminates the search.
The decnet_router-l1 keyword refers to the multicast address for all level-1 routers, which are intra-area routers, and the decnet_router-l2 keyword refers to all level 2 routers, which are interarea routers.
Use Tables 5-8, 5-9, and 5-10 from the priority-list protocol command to configure custom queuing for your system.
The following example assigns 1 as the custom queue list, specifies DECnet as the protocol type, and assigns 3 as a queue number to the packets transmitted on this interface:
queue-list 1 protocol decnet 3
The following example assigns DECnet packets with a size greater than 200 bytes to queue number 2:
queue-list 2 protocol decnet 2 gt 200
The following example assigns DECnet packets with a size less than 200 bytes to queue number 2:
queue-list 4 protocol decnet 2 lt 200
The following example assigns traffic that matches IP access list 10 to queue number 1:
queue-list 1 protocol ip 1 list 10
The following example assigns Telnet packets to queue number 2:
queue-list 4 protocol ip 2 tcp 23
The following example assigns UDP Domain Name service packets to queue number 2:
queue-list 4 protocol ip 2 udp 53
The following example assigns traffic that matches Ethernet type code access list 201 to queue number 1:
queue-list 1 protocol bridge 1 list 201
A dagger (+) indicates that the command is documented in another chapter.
custom-queue-list +
show queueing
To designate the byte size allowed per queue, use the queue-list queue byte-count global configuration command. To return the byte size to the default value, use the no form of the command.
queue-list list-number queue queue-number byte-count byte-count-number| list-number | Number of the queue list. An integer from 1 to 10. |
|---|---|
| queue-number | Number of the queue. An integer from 1 to 10. |
| byte-count-number | Specifies the lower boundary on how many bytes the system allows to be delivered from a given queue during a particular cycle. |
1500 bytes
Global configuration
In the following example, queue list 9 establishes the byte-count as 1400 for queue number 10:
queue-list 9 queue 10 byte-count 1400
A dagger (+) indicates that the command is documented in another chapter.
custom-queue-list +
show queueing
To designate the queue length limit for a queue, use the queue-list queue limit global configuration command. To return the queue length to the default value, use the no form of the command.
queue-list list-number queue queue-number limit limit-number| list-number | Number of the queue list. An integer from 1 to 10. |
|---|---|
| queue-number | Number of the queue. An integer from 1 to 10. |
| limit-number | Maximum number of packets which can be enqueued at any time. Range is 0 to 32767 queue entries. |
20 entries
Global configuration
In the following example, the queue length of queue 10 is increased to 40:
queue-list 5 queue 10 limit 40
A dagger (+) indicates that the command is documented in another chapter.
custom-queue-list +
show queueing
To establish queuing priorities based on the address of the serial link on a STUN connection, use the queue-list stun global configuration command. Use the no queue-list stun command with the appropriate arguments to remove an entry from the list.
queue-list list-number stun queue-number address group-number address-number| list-number | Number of the queue list. An integer from 1 to 10. |
| queue-number | Queue number in the range from 1 to 10. |
| address | Required keyword. |
| group-number | Group number used in the stun group command. |
| address-number | Address of the serial link. The format of the address is either a 1-byte hex value (for example, C1) for an SDLC link or one that is specified by the stun schema configuration command. |
None
Global configuration
The following example causes the system to place STUN traffic matching the STUN group number 2 and address C1 onto queue number 3:
queue-list 3 stun 3 address 2 c1
A dagger (+) indicates that the command is documented in another chapter.
custom-queue-list +
show queueing
stun schema +
To control the maximum amount of time that can elapse without running the lowest-priority system processes, use the scheduler-interval global configuration command. The no scheduler-interval command restores the default.
scheduler-interval milliseconds| milliseconds | Integer that specifies the interval, in milliseconds. The minimum interval that you can specify is 500 milliseconds; there is no maximum value. |
High-priority operations are allowed to use as much of the central processor as needed.
Global configuration
The normal operation of the network server allows the switching operations to use as much of the central processor as is required. If the network is running unusually heavy loads that do not allow the processor the time to handle the routing protocols, give priority to the system process scheduler.
The following example changes the low-priority process schedule to an interval of 750 milliseconds:
scheduler-interval 750
To delay the startup of the EXEC on noisy lines, use the service exec-wait global configuration command. Use the no service exec-wait command to disable this feature.
service exec-waitThis command has no arguments or keywords.
Disabled
Global configuration
This command delays startup of the EXEC until the line has been idle (no traffic seen) for 3 seconds. The default is to enable the line immediately on modem activation.
This command is useful on noisy modem lines or when a modem attached to the line is configured to ignore MNP or V.42 negotiations, and MNP or V.42 modems may be dialing in. In these cases, noise or MNP/V.42 packets may be interpreted as usernames and passwords, causing authentication failure before the user gets a chance to type a username/password. The command is not useful on non-modem lines or lines without some kind of login configured.
The following example delays the startup of the EXEC:
service exec-wait
To allow Finger protocol requests (defined in RFC 742) to be made of the network server, use the service finger global configuration command. This service is equivalent to issuing a remote show users command. The no service finger command removes this service.
service fingerThis command has no arguments or keywords.
Enabled
Global configuration
The following is an example of how to disable the Finger protocol:
no service finger
To enable the Nagle congestion control algorithm, use the service nagle global configuration command. Use the no service nagle command to disable this feature.
service nagleThis command has no arguments or keywords.
Disabled
Global configuration
When using a standard TCP implementation to send keystrokes between machines, TCP tends to send one packet for each keystroke typed. On larger networks, many small packets use up bandwidth and contribute to congestion.
John Nagle's algorithm (RFC 896) helps alleviate the small-packet problem in TCP. In general, it works this way: The first character typed after connection establishment is sent in a single packet, but TCP holds any additional characters typed until the receiver acknowledges the previous packet. Then the second, larger packet is sent, and additional typed characters are saved until the acknowledgment comes back. The effect is to accumulate characters into larger chunks, and pace them out to the network at a rate matching the round-trip time of the given connection. This method is usually a good for all TCP-based traffic. However, do not use the service nagle command if you have XRemote users on X Window sessions.
The following example enables the Nagle algorithm on the router:
service nagle
To encrypt passwords, use the service password-encryption global configuration command. Use the no service password-encryption command to disable this service.
service password-encryptionThis command has no arguments or keywords.
No encryption
Global configuration
The actual encryption process occurs when the current configuration is written or when a password is configured. Password encryption can be applied to both the privileged command password and to console and virtual terminal line access passwords.
When password encryption is enabled, the encrypted form of the passwords is displayed when a show configuration command is entered.
The following example causes password encryption to take place:
service password-encryption
To generate keepalive packets on idle network connections, use the service tcp-keepalives global configuration command. The no service tcp-keepalives command with the appropriate keyword disables the keepalives.
service tcp-keepalives {in | out}| in | Generates keepalives on incoming connections (initiated by remote host). |
| out | Generates keepalives on outgoing connections (initiated by a user). |
Disabled
Global configuration
The following example generates keepalives on incoming TCP connections:
service tcp-keepalives in
To set the TCP window to zero (0) when the Telnet connection is idle, use the service telnet-zero-idle global configuration command. Use the no service telnet-zero-idle command to disable this feature.
service telnet-zero-idleThis command has no arguments or keywords.
Disabled
Global configuration
Normally, data sent to non-current Telnet connections is accepted and discarded. When service telnet-zero-idle is enabled, if a session is suspended (that is, some other connection is made active or the EXEC is sitting in command mode), the TCP window is set to zero. This action prevents the remote host from sending any more data until the connection is resumed. Use this command when it is important that all messages sent by the host be seen by the users and the users are likely to use multiple sessions.
Do not use this command if your host will eventually time out and log out a TCP user whose window is zero.
The following example sets the TCP window to zero when the Telnet connection is idle:
service telnet-zero-idle
resume
To configure the system to timestamp debugging or logging messages, use one of the service timestamps global configuration commands. Use the no service timestamps command to disable this service.
service timestamps [type uptime]| type | Type of message to timestamp: debug or log. |
| uptime | (Optional) Timestamp with time since the system was rebooted. |
| datetime | Timestamp with the date and time. |
| msec | (Optional) Include milliseconds in the date and timestamp. |
| localtime | (Optional) Timestamp relative to the local time zone. |
| show-timezone | (Optional) Include the time zone name in the timestamp. |
No timestamping.
If service timestamps is specified with no arguments or keywords, default is service timestamps debug uptime.
The default for service timestamps type datetime is to format the time in UTC, with no milliseconds and no time zone name.
The command no service timestamps by itself disables timestamps for both debug and log messages.
Global configuration
Timestamps can be added to either debugging or logging messages independently. The uptime form of the command adds timestamps in the format HHHH:MM:SS, indicating the time since the system was rebooted. The datetime form of the command adds timestamps in the format
MMM DD HH:MM:SS, indicating the date and time according to the system clock. If the system clock has not been set, the date and time are preceded by an asterisk (*) to indicate that the date and time are probably not correct.
The following example enables timestamps on debugging messages, showing the time since reboot:
service timestamps debug uptime
The following example enables timestamps on logging messages, showing the current time and date relative to the local time zone, with the time zone name included:
service timestamps log datetime localtime show-timezone
clock set
debug (Refer to the Debug Command Reference publication.)
ntp
Use the show buffers EXEC command to display statistics for the buffer pools on the network server.
The network server has one pool of queuing elements and five pools of packet buffers of different sizes. For each pool, the network server keeps counts of the number of buffers outstanding, the number of buffers in the free list, and the maximum number of buffers allowed in the free list.
show buffers [interface]| interface | (Optional) Causes a search of all buffers that have been associated with that interface for longer than one minute. The contents of these buffers are printed to the screen. This option is useful in diagnosing problems where the input queue count on an interface is consistently nonzero. |
EXEC
The following is sample output from the show buffers command when the optional interface argument was omitted:
Router# show buffers
Buffer elements:
250 in free list (250 max allowed)
10816 hits, 0 misses, 0 created
Small buffers, 104 bytes (total 120, permanent 120):
120 in free list (0 min, 250 max allowed)
26665 hits, 0 misses, 0 trims, 0 created
Middle buffers, 600 bytes (total 90, permanent 90):
90 in free list (0 min, 200 max allowed)
5468 hits, 0 misses, 0 trims, 0 created
Big buffers, 1524 bytes (total 90, permanent 90):
90 in free list (0 min, 300 max allowed)
1447 hits, 0 misses, 0 trims, 0 created
Large buffers, 5024 bytes (total 0, permanent 0):
0 in free list (0 min, 100 max allowed)
0 hits, 0 misses, 0 trims, 0 created
Huge buffers, 12024 bytes (total 0, permanent 0):
0 in free list (0 min, 30 max allowed)
0 hits, 0 misses, 0 trims, 0 created
0 failures (0 no memory)
Table 5-12 describes significant fields shown in the display.
| Field | Description |
|---|---|
| Buffer elements | Buffer elements are small structures used as placeholders for buffers in internal operating system queues. Buffer elements are used when a buffer may need to be on more than one queue. |
| 250 in free list (250 max allowed) | Maximum number of buffers that are available for allocation. |
| 10816 hits | Count of successful attempts to allocate a buffer when needed. |
| 0 misses | Count of buffer allocation attempts that resulted in growing the buffer pool in order to allocate a buffer. |
| 0 created | Count of new buffers created to satisfy buffer allocation attempts when the available buffers in the pool have already been allocated. |
| Small buffers | Blocks of memory used to hold network packets. The sizes of these buffers can vary as follows: small, middle, big, large and huge. |
| 104 bytes | Size of this type of buffer. |
| (total 120, permanent 120) | Total number of this type of buffer, and the number of these buffers that are permanent. |
| 0 trims | Count of buffers released to the system because they were not being used. |
| 0 created | Count of new buffers created in response to misses. |
| 0 failures | Total number of allocation requests that have failed because no buffer was available for allocation; the datagram was lost. Such failures normally occur at interrupt level. |
| (0 no memory) | Number of failures because no memory was available to create a new buffer. |
To display the calendar hardware setting for the Cisco 7000 or Cisco 4500, use the show calendar EXEC command:
show calendarThis command has no arguments or keywords.
EXEC
You can compare the time and date shown with this command with the time and date listed via the show clock command to verify that the calendar and system clock are in sync with each other. The time displayed is relative to the configured time zone.
In the following sample display, the hardware calendar indicates the timestamp of 12:13:44 p.m. on Friday, January 1, 1993:
Router# show calendar
12:13:44 PST Fri Jan 1 1993
show clock
To display the system clock, use the show clock EXEC command:
show clock [detail]| detail | (Optional) Indicates the clock source (NTP, VINES, 7000 calendar, and so forth) and the current summer-time setting (if any). |
EXEC
The system clock keeps an "authoritative" flag that indicates whether or not the time is authoritative (believed to be accurate). If system clock has been set by a timing source (Cisco 7000 calendar, NTP, VINES, and so forth), the flag is set. If the time is not authoritative, it will be used only for display purposes. Until the clock is authoritative and the "authoritative" flag is set, the flag prevents the router from causing peers to synchronize to itself when the router time is invalid.
The symbol that precedes the show clock display indicates the following:
* indicates not authoritative
blank indicates authoritative
. indicates authoritative, but NTP is not synchronized
The following sample output shows that the current clock is authoritative and that the time source is NTP:
Router# show clock detail
15:29:03.158 PST Mon Mar 1 1993
Time source is NTP
Router#
clock set
show calendar
Use the show environment EXEC command to display temperature and voltage information on the AGS+ and Cisco 7000 series console.
show environmentThis command has no arguments or keywords.
EXEC
Once a minute a routine is run that gets environmental measurements from the CSC-ENVM card and stores the show environment output into a buffer. This buffer is displayed on the console when show environment is invoked.
If a measurement exceeds desired margins, but has not exceeded fatal margins, a warning message is printed to the system console. The system software queries the CSC-ENVM card for measurements once a minute, but warnings for a given testpoint are printed at most once every four hours. If a measurement is out of line within a four-hour period, an automatic warning message appears on the console. As noted above, you can query the CSC-ENVM using the show environment command at any time to determine if a measurement is at the warning tolerance.
The following is sample output from the show environment command on the AGS+:
Router# show environment
Environmental controller firmware version 2.0
Serial number is 00220846, calibrated on 2-14-92, by technician rma
Internal temperature measured 34.3(C), shuts down at 43.0(C)
Air flow appears good.
+5 volt line measured at 5.061(V)
+12 volt line measured at 12.120(V)
-12 volt line measured at -11.936(V)
-5 volt line measured at -4.986(V)
Table 5-13 describes significant fields shown in the display.
| Field | Description |
|---|---|
| Serial number is 00220846 | Serial number of router. |
| calibrated on 2-14-92 | Date on which these measurements were taken. |
| by technician rma | ID (initials in this case) of the technician taking the measurement. |
| Internal temperature measured 34.3 (C) | Internal temperature of the router (in celsius). |
| shuts down at 43.0(C) | Temperature (in celsius) at which the router is administratively shut down to prevent internal damage. |
| Air flow appears good. | Air flow is adequate for proper router operation. |
| +5 volt line at 5.061(V) | Voltage measurement of the +5 volt line. |
| +12 volt line measured at 12.120(V) | Voltage measurement of the +12 volt line. |
| -12 volt line measured at -11.936(V) | Voltage measurement of the -12 volt line. |
| -5 volt line measured at -4.986(V) | Voltage measurement of the -5 volt line. |
The following is an example of a message that displays on the system console when a measurement has exceeded an acceptable margin:
Router#
ENVIRONMENTAL WARNING: Air flow appears marginal.
The following is an example of a message that displays on the system console when a measurement has exceeded an acceptable margin. In this example, the internal temperature reading is given:
Router#
ENVIRONMENTAL WARNING: Internal temperature measured 41.3(C)
The following is an example of a message that displays on the system console when a voltage measurement has exceeded an acceptable margin:
Router#
ENVIRONMENTAL WARNING: +5 volt testpoint measured 5.310(V)
If the CSC-ENVM card on the AGS+ chassis detects that any of its voltage or temperature testpoints has exceeded maximum margins, it does the following in this order:
The following is the message the system displays if voltage or temperature exceed maximum margins:
Router#
SHUTDOWN: air flow problem
For environmental specifications, refer to the Hardware Installation and Maintenance publication for your individual chassis.
The following example shows the typical show environment display on the Cisco 7000 when there are no warning conditions in the system. The date and time of the query are displayed, along with the data refresh information and a message indicating that there are no warning conditions.
Router> show environment
Environmental Statistics
Environmental status as of 13:17:39 UTC Thu Oct 22 1992
Data is 7 second(s) old, refresh in 53 second(s)
All Environmental Measurements are within specifications
Table 5-14 describes the show environment display fields on the Cisco 7000.
| Field | Description |
|---|---|
| Environmental status as of... | Current date and time. |
| Data age and refresh | Environmental measurements are output into a buffer every 60 seconds, unless other higher-priority processes are running. |
| WARNING | If environmental measurements are not within specification, warning messages are displayed. |
Use the show environment all EXEC command to display temperature and voltage information on the Cisco 7000 series console.
show environment allThis command has no arguments or keywords.
EXEC
The following is sample output from the show environment all command on the Cisco 7000 when there are no warning conditions in the system:
7000> show environment all
Environmental Statistics
Environmental status as of 13:17:39 UTC Thu Oct 22 1992
Data is 11 second(s) old, refresh in 49 second(s)
All Environmental Measurements are within specifications
Lower Power Supply: 700W, ON Upper Power Supply: Not Installed
No Intermittent Powerfails
+12 volt measured at 12.05(V)
+5 volt measured at 4.92(V)
-12 volt measured at -12.00(V)
+24 volt measured at 23.80(V)
Airflow temperature measured at 30(C)
Inlet temperature measured at 25(C)
In the following example, there have been two intermittent power failures since the router was turned on, and the lower power supply is not functioning. The last intermittent power failure occurred on Sunday, October 25, 1992, at 11:07 p.m.
7000# show environment all
Environmental Statistics
Environmental status as of 23:19:47 UTC Sun Oct 25 1992
Data is 6 second(s) old, refresh in 54 second(s)
WARNING: Lower Power Supply is NON-OPERATIONAL
Lower Power Supply:700W, OFF Upper Power Supply: 700W, ON
Intermittent Powerfail(s): 2 Last on 23:07:05 UTC Sun Oct 25 1992
+12 volts measured at 12.05(V)
+5 volts measured at 4.96(V)
-12 volts measured at -12.05(V)
+24 volts measured at 23.80(V)
Airflow temperature measured at 38(C)
Inlet temperature measured at 25(C)
Table 5-15 describes the show environment all display fields.
| Field | Description |
|---|---|
| Environmental status as of... | Date and time of last query. |
| Data age and refresh | Environmental measurements are output into a buffer every 60 seconds, unless other higher-priority processes are running. |
| WARNING | If environmental measurements are not within specification, warning messages are displayed. |
| Lower Power Supply | Type of power supply installed and its status (on or off). |
| Upper Power Supply | Type of power supply installed and its status (on or off). |
| Intermittent Powerfails | Number of power hits (not resulting in shutdown) since system was last booted. |
| Voltage Specifications | System voltage measurements. |
| Airflow and Inlet temperature | Temperature of air coming in and going out. |
The following example shows typical output of the show environment all command on the Cisco 7010. The output shows the status of the single 600W power supply. The following example from a Cisco 7010 shows that a single 600W power supply is installed:
7010# show environment all
Environmental Statistics
Environmental status as of Fri 11-5-1993 19:10:41
Data is 31 second(s) old, refresh in 29 second(s)
All Environmental Measurements are within specifications
Power Supply: 600W AC
No Intermittent Powerfails
+12 volts measured at 12.00(V)
+5 volts measured at 5.02(V)
-12 volts measured at -12.05(V)
+24 volts measured at 23.70(V)
Airflow temperature measured at 35(C)
Inlet temperature measured at 26(C)
Table 5-16 describes the fields shown in the display.
| Field | Description |
|---|---|
| Environmental status as of... | Current date and time. |
| Data age and refresh | Environmental measurements are output into a buffer every 60 seconds, unless other higher-priority processes are running. |
| All Environmental Measurements are within specifications | All environment measurements are within specification. If they are not, warning messages are displayed. |
| Power Supply: | Type of power supply. |
| No Intermittent Powerfails | Indicates whether intermittent power failures are occurring. |
| +12 volts measured at 12.00(V) | Voltage measurement of the +12 volt line. |
| +5 volts measured at 5.02(V) | Voltage measurement of the +5 volt line. |
| -12 volts measured at -12.05(V) | Voltage measurement of the -12 volt line. |
| +24 volts measured at 23.70(V) | Voltage measurement of the +24 volt line. |
If a shutdown occurs due to detection of fatal environmental margins, the CSC-ENVM (on the AGS+) or the route processor (RP) (on the Cisco 7000 series) logs the last measured value from each of the six test points to internal nonvolatile memory. Only one set of measurements may be stored at any one time.
Use the show environment last EXEC command to display these test points.
show environment lastThis command has no arguments or keywords.
EXEC
The following is sample output from the show environment last command on the AGS+:
Router# show environment last
Environmental controller firmware version 2.0
Serial number is 3232, calibrated on 2-14-92, by technician rma
Internal temperature measured 24.1(C), shuts down at 43.0(C)
Air flow appears good.
+5 volt line measured at 4.988(V)
+12 volt line measured at 12.044(V)
-12 volt line measured at -11.787(V)
-5 volt line measured at -4.939(V)
LAST Environmental Shutdown Measurements:
Internal temperature was 24.0(C)
Air flow sensor was good
+5 volt line was 4.990(V)
+12 volt line was 9.900(V)*
-12 volt line was -11.719(V)
-5 volt line was -4.926(V)
As the display shows, the first block of data is equivalent to show environment, in that it displays the current measurements. The second block shows all the testpoint values at the time of the LAST environmental shutdown. An asterisk suffixes the testpoint that caused the failure. In this example, the +12 volt testpoint dropped to 9.900(V) to cause the shutdown.
The following example is for the Cisco 7000. The router retrieves the environmental statistics at the time of the last shutdown. In this example, the last shutdown was Tuesday, May 19, 1992 at 12:40p.m., so the environmental statistics at that time are displayed.
Router# show environment last
Environmental Statistics
Environmental status as of 14:47:00 UTC Thu May 21 1992
Data is 6 second(s) old, refresh in 54 second(s)
WARNING: Upper Power Supply is NON-OPERATIONAL
LAST Environmental Statistics
Environmental status as of 12:40:00 UTC Tues May 19 1992
Lower Power Supply: 700W, ON Upper Power Supply: 700W, OFF
No Intermittent Powerfails
+12 volts measured at 12.05(V)
+5 volts measured at 4.98(V)
-12 volts measured at -12.00(V)
+24 volts measured at 23.80(V)
Airflow temperature measured at 30(C)
Inlet temperature measured at 23(C)
Table 5-17 describes the show environment last display fields.
| Field | Description |
|---|---|
| Environmental status as of... | Current date and time. |
| Data age and refresh | Environmental measurements are output into a buffer every 60 seconds, unless other higher-priority processes are running. |
| WARNING | If environmental measurements are not within specification, warning messages are displayed. |
| LAST | Displays test point values at time of the last environmental shutdown. |
| Lower Power Supply/Upper Power Supply Power Supply: | For the Cisco 7000, indicates the status of the two 700W power supplies. For the Cisco 7010, indicates the status of the single 600W power supply. |
Use the show environment table EXEC command to display environmental measurements and a table that lists the ranges of environment measurement that are within specification. This command is available on the Cisco 7000 only.
show environment tableThis command has no arguments or keywords.
EXEC
The following sample output shows the current environmental status in tables that list voltage and temperature parameters. There are three warning messages; one each about the lower power supply, the airflow temperature, and the inlet temperature. In this example, voltage parameters are shown to be in the normal range, airflow temperature is at a critical level, and inlet temperature is at the warning level.
Router> show environment table
Environmental Statistics
Environmental status as of Mon 11-2-1992 17:43:36
Data is 52 second(s) old, refresh in 8 second(s)
WARNING: Lower Power Supply is NON-OPERATIONAL
WARNING: Airflow temperature has reached CRITICAL level at 73(C)
WARNING: Inlet temperature has reached WARNING level at 41(C)
Voltage Parameters:
SENSE CRITICAL NORMAL CRITICAL
-------|--------------------|------------------------|--------------------
+12(V) 10.20 12.05(V) 13.80
+5(V) 4.74 4.98(V) 5.26
-12(V) -10.20 -12.05(V) -13.80
+24(V) 20.00 24.00(V) 28.00
Temperature Parameters:
SENSE WARNING NORMAL WARNING CRITICAL SHUTDOWN
-------|-------------|------------|-------------|--------------|--------------
Airflow 10 60 70 73(C) 88
Inlet 10 39 41(C) 46 64
Table 5-18 describes the show environment table display fields.
| Field | Description |
|---|---|
| SENSE (Voltage Parameters) | Voltage specification for DC line. |
| SENSE (Temperature Parameters) | Air being measured. Inlet measures the air coming in, and Airflow measures the temperature of the air inside the chassis. |
NORMAL
| All monitored conditions meet normal requirements. |
WARNING
| System is approaching an out-of-tolerance condition. |
CRITICAL
| Out-of-tolerance condition exists. |
PROCESSOR SHUTDOWN
| Processor has detected condition that could cause physical damage to the system. |
Use the show logging EXEC command to display the state of logging (syslog).
show loggingThis command displays the state of syslog error and event logging, including host addresses, and whether console logging is enabled. This command also displays Simple Network Management Protocol (SNMP) configuration parameters and protocol activity.
This command has no arguments or keywords.
EXEC
The following is sample output from the show logging command:
Router# show logging
Syslog logging: enabled
Console logging: disabled
Monitor logging: level debugging, 266 messages logged.
Trap logging: level informational, 266 messages logged.
Logging to 131.108.2.238
SNMP logging: disabled, retransmission after 30 seconds
0 messages logged
Table 5-19 describes significant fields shown in the display.
| Field | Description |
|---|---|
| Syslog logging | When enabled, system logging messages are sent to a UNIX host that acts as a syslog server; that is, it captures and saves the messages. |
| Console logging | If enabled, states the level; otherwise, this field displays disabled. |
| Monitor logging | Minimum level of severity required for a log message to be sent to a monitor terminal (not the console). |
| Trap logging | Minimum level of severity required for a log message to be sent to a syslog server. |
| SNMP logging | Shows whether SNMP logging is enabled and the number of messages logged, and the retransmission interval. |
Use the show memory EXEC command to show statistics about the router's memory, including memory free pool statistics.
show memory [type] [free]| type | (Optional) Memory type to display (processor, multibus, io, sram). If type is not specified, statistics for all memory types present in the router will be displayed. |
| free | (Optional) Displays free memory statistics. |
EXEC
The following is sample output from the show memory command:
Router# show memory
Head FreeList Total(b) Used(b) Free(b) Largest(b)
Processor 2E0FF8 2AABFC 13758472 847216 12911256 12908036
Processor memory
Address Bytes Prev. Next Ref PrevF NextF Alloc PC What
2E0FF8 2128 0 2E1848 1 84352 *Init*
2E1848 2052 2E0FF8 2E204C 1 86184 *Init*
2E204C 564 2E1848 2E2280 1 861B0 *Init*
2E2280 2052 2E204C 2E2A84 1 1266 *Init*
2E2A84 308 2E2280 2E2BB8 1 44974 *Init*
2E2BB8 220 2E2A84 2E2C94 1 3F788 *Init*
2E2C94 2052 2E2BB8 2E3498 1 3F7A8 *Init*
2E3498 4052 2E2C94 2E446C 1 46770 *Init*
2E446C 516 2E3498 2E4670 1 44E4C *Packet Buffer*
2E4670 516 2E446C 2E4874 1 44E4C *Packet Buffer*
2E4874 516 2E4670 2E4A78 1 44E4C *Packet Buffer*
2E4A78 516 2E4874 2E4C7C 1 44E4C *Packet Buffer*
2E4C7C 516 2E4A78 2E4E80 1 44E4C *Packet Buffer*
2E4E80 516 2E4C7C 2E5084 1 44E4C *Packet Buffer*
2E5084 516 2E4E80 2E5288 1 44E4C *Packet Buffer*
2E5288 516 2E5084 2E548C 1 44E4C *Packet Buffer*
2E548C 516 2E5288 2E5690 1 44E4C *Packet Buffer*
2E5690 516 2E548C 2E5894 1 44E4C *Packet Buffer*
Router#
The following is sample output from the show memory free command:
Router# show memory free
Head FreeList Total(b) Used(b) Free(b) Largest(b)
Processor 2E0FF8 2AABFC 13758472 847120 12911352 12908036
Processor memory
Address Bytes Prev. Next Ref PrevF NextF Alloc PC What
72 Free list 1
88 Free list 2
96 Free list 3
384A04 96 38496C 384A64 0 0 0 1205A4 IGRP Router
108 Free list 4
124 Free list 5
Final freespace block
3B09FC 12908036 3B0834 0 0 0 0 76162 (coalesced)
The display of show memory free contains the same types of information as the show memory display, except that only free memory is displayed, and the information is displayed in order for each free list.
The first section of the display includes summary statistics about the activities of the system memory allocator. Table 5-20 describes significant fields shown in the first section of the display.
| Field | Description |
|---|---|
| Head | Hexadecimal address of the head of the memory allocation chain. |
| FreeList | Hexadecimal address of the base of the free list. |
| Total (b) | Sum of used bytes plus free bytes. |
| Used (b) | Amount of memory in use. |
| Free (b) | Amount of memory not in use. |
| Largest (b) | Size of largest available free block. |
The second section of the display is a block-by-block listing of memory use. Table 5-21 describes significant fields shown in the second section of the display.
| Field | Description |
|---|---|
| Address | Hexadecimal address of block. |
| Bytes | Size of block in bytes. |
| Prev. | Address of previous block (should match Address on previous line). |
| Next | Address of next block (should match address on next line). |
| Ref | Reference count for that memory block, indicating how many different processes are using that block of memory. |
| PrevF | Address of previous free block (if free). |
| NextF | Address of next free block (if free). |
| Alloc PC | Address of the system call that allocated the block. |
| What | Name of process that owns the block, or "(fragment)" if the block is a fragment, or "(coalesced)" if the block was coalesced from adjacent free blocks. |
The show memory io command displays the free IO memory blocks. On the Cisco 4000, this command quickly shows how much unused IO memory is available.
The following is sample output from the show memory io command:
Router# show memory io
Address Bytes Prev. Next Ref PrevF NextF Alloc PC What
6132DA0 59264 6132664 6141520 0 0 600DDEC 3FCF0 *Packet Buffer*
600DDEC 500 600DA4C 600DFE0 0 6132DA0 600FE68 0
600FE68 376 600FAC8 600FFE0 0 600DDEC 6011D54 0
6011D54 652 60119B4 6011FEO 0 600FE68 6013D54 0
614FCA0 832 614F564 614FFE0 0 601FD54 6177640 0
6177640 2657056 6172E90 0 0 614FCA0 0 0
Total: 2723244
The show memory sram command displays the free SRAM memory blocks. For the Cisco 4000, this command supports the high-speed static RAM memory pool to make it easier to debug or diagnose problems with allocation or freeing of such memory.
The following is sample output from the show memory sram command:
Router# show memory sram
Address Bytes Prev. Next Ref PrevF NextF Alloc PC What
7AE0 38178 72F0 0 0 0 0 0
Total 38178
The show memory command on the Cisco 4000 includes information about SRAM memory and IO memory, and appears as follows:
Router# show memory
Head Free Start Total Bytes Used Bytes Free Bytes
SRAM 1000 7AE0 65538 27360 38178
Processor 20CFC4 23E178 2043964 282372 1761592
IO memory 6000000 6132DA0 4194656 1471412 2723244
Address Bytes Prev. Next Ref PrevF NextF Alloc PC What
1000 2032 0 17F0 1 3E73E *Init*
17F0 2032 1000 1FE0 1 3E73E *Init*
1FE0 544 17F0 2200 1 3276A *Init*
2200 52 1FE0 2234 1 31D68 *Init*
2234 52 2200 2268 1 31DAA *Init*
2268 52 2234 229C 1 31DF2 *Init*
72F0 2032 6E5C 7AE0 1 3E73E Init
7AE0 38178 72F0 0 0 0 0 0
Router#
To show the status of Network Time Protocol (NTP) associations, use the show ntp associations EXEC command.
show ntp associations [detail]| detail | (Optional) Shows detailed information about each NTP association. |
EXEC
Detailed descriptions of the information displayed by this command can be found in the NTP specification (RFC 1305).
The following is sample output from the show ntp associations command:
Router# show ntp associations
address ref clock st when poll reach delay offset disp
~160.89.32.2 160.89.32.1 5 29 1024 377 4.2 -8.59 1.6
+~131.108.13.33 131.108.1.111 3 69 128 377 4.1 3.48 2.3
*~131.108.13.57 131.108.1.111 3 32 128 377 7.9 11.18 3.6
* master (synced), # master (unsynced), + selected, - candidate, ~ configured
Router#
Table 5-22 describes significant fields shown in the display.
| Field | Description |
|---|---|
address | Address of peer. |
| ref clock | Address of peer's reference clock. |
| st | Peer's stratum. |
| when | Time since last NTP packet received from peer. |
| poll | Polling interval (seconds). |
| reach | Peer reachability (bit string, in octal). |
| delay | Round-trip delay to peer (milliseconds). |
| offset | Relative time of peer's clock to local clock (milliseconds). |
| disp | Dispersion |
The first character of the line can be one or more of the following: | |
| * | Synchronized to this peer. |
| # | Almost synchronized to this peer. |
| + | Peer selected for possible synchronization. |
| - | Peer is a candidate for selection. |
| ~ | Peer is statically configured. |
The following is sample output of the show ntp associations detail command:
Router# show ntp associations detail
160.89.32.2 configured, insane, invalid, stratum 5
ref ID 160.89.32.1, time AFE252C1.6DBDDFF2 (00:12:01.428 PDT Mon Jul 5 1993)
our mode active, peer mode active, our poll intvl 1024, peer poll intvl 64
root delay 137.77 msec, root disp 142.75, reach 376, sync dist 215.363
delay 4.23 msec, offset -8.587 msec, dispersion 1.62
precision 2**19, version 3
org time AFE252E2.3AC0E887 (00:12:34.229 PDT Mon Jul 5 1993)
rcv time AFE252E2.3D7E464D (00:12:34.240 PDT Mon Jul 5 1993)
xmt time AFE25301.6F83E753 (00:13:05.435 PDT Mon Jul 5 1993)
filtdelay = 4.23 4.14 2.41 5.95 2.37 2.33 4.26 4.33
filtoffset = -8.59 -8.82 -9.91 -8.42 -10.51 -10.77 -10.13 -10.11
filterror = 0.50 1.48 2.46 3.43 4.41 5.39 6.36 7.34
131.108.13.33 configured, selected, sane, valid, stratum 3
ref ID 131.108.1.111, time AFE24F0E.14283000 (23:56:14.078 PDT Sun Jul 4 1993)
our mode client, peer mode server, our poll intvl 128, peer poll intvl 128
root delay 83.72 msec, root disp 217.77, reach 377, sync dist 264.633
delay 4.07 msec, offset 3.483 msec, dispersion 2.33
precision 2**6, version 3
org time AFE252B9.713E9000 (00:11:53.442 PDT Mon Jul 5 1993)
rcv time AFE252B9.7124E14A (00:11:53.441 PDT Mon Jul 5 1993)
xmt time AFE252B9.6F625195 (00:11:53.435 PDT Mon Jul 5 1993)
filtdelay = 6.47 4.07 3.94 3.86 7.31 7.20 9.52 8.71
filtoffset = 3.63 3.48 3.06 2.82 4.51 4.57 4.28 4.59
filterror = 0.00 1.95 3.91 4.88 5.84 6.82 7.80 8.77
131.108.13.57 configured, our_master, sane, valid, stratum 3
ref ID 131.108.1.111, time AFE252DC.1F2B3000 (00:12:28.121 PDT Mon Jul 5 1993)
our mode client, peer mode server, our poll intvl 128, peer poll intvl 128
root delay 125.50 msec, root disp 115.80, reach 377, sync dist 186.157
delay 7.86 msec, offset 11.176 msec, dispersion 3.62
precision 2**6, version 2
org time AFE252DE.77C29000 (00:12:30.467 PDT Mon Jul 5 1993)
rcv time AFE252DE.7B2AE40B (00:12:30.481 PDT Mon Jul 5 1993)
xmt time AFE252DE.6E6D12E4 (00:12:30.431 PDT Mon Jul 5 1993)
filtdelay = 49.21 7.86 8.18 8.80 4.30 4.24 7.58 6.42
filtoffset = 11.30 11.18 11.13 11.28 8.91 9.09 9.27 9.57
filterror = 0.00 1.95 3.91 4.88 5.78 6.76 7.74 8.71
Table 5-23 describes significant fields shown in the display.
| Field | Descriptions |
|---|---|
| configured | Peer was statically configured. |
| dynamic | Peer was dynamically discovered. |
| our_master | Local machine is synchronized to this peer. |
| selected | Peer is selected for possible synchronization. |
| candidate | Peer is a candidate for selection. |
| sane | Peer passes basic sanity checks. |
| insane | Peer fails basic sanity checks. |
| valid | Peer time is believed to be valid. |
| invalid | Peer time is believed to be invalid. |
| leap_add | Peer is signaling that a leap second will be added. |
| leap-sub | Peer is signaling that a leap second will be subtracted. |
| unsynced | Peer is not synchronized to any other machine. |
| ref ID | Address of machine peer is synchronized to. |
| time | Last timestamp peer received from its master. |
| our mode | Our mode relative to peer (active / passive / client / server / bdcast / bdcast client). |
| peer mode | Peer's mode relative to us. |
| our poll ivl | Our poll interval to peer. |
| peer poll ivl | Peer's poll interval to us. |
| root delay | Delay along path to root (ultimate stratum 1 time source). |
| root disp | Dispersion of path to root. |
| reach | Peer reachability (bit string in octal). |
| sync dist | Peer synchronization distance. |
| delay | Round trip delay to peer. |
| offset | Offset of peer clock relative to our clock. |
| dispersion | Dispersion of peer clock. |
| precision | Precision of peer clock in Hz. |
| version | NTP version number that peer is using. |
| org time | Originate time stamp. |
| rcv time | Receive time stamp. |
| xmt time | Transmit time stamp. |
| filtdelay | Round trip delay in milliseconds of each sample. |
| filtoffset | Clock offset in milliseconds of each sample. |
| filterror | Approximate error of each sample. |
To show the status of Network Time Protocol (NTP), use the show ntp status EXEC command.
show ntp statusThis command has no arguments or keywords.
EXEC
The following is sample output from the show ntp status command:
Router# show ntp status
Clock is synchronized, stratum 4, reference is 131.108.13.57
nominal freq is 250.0000 Hz, actual freq is 249.9990 Hz, precision is 2**19
reference time is AFE2525E.70597B34 (00:10:22.438 PDT Mon Jul 5 1993)
clock offset is 7.33 msec, root delay is 133.36 msec
root dispersion is 126.28 msec, peer dispersion is 5.98 msec
Router#
Table 5-24 shows the significant fields in the display.
| Field | Description |
|---|---|
| synchronized | System is synchronized to an NTP peer. |
| unsynchronized | System is not synchronized to any NTP peer. |
| stratum | NTP stratum of this system. |
| reference | Address of peer we are synchronized to. |
| nominal freq | Nominal frequency of system hardware clock. |
| actual freq | Measured frequency of system hardware clock. |
| precision | Precision of this system's clock (in Hz). |
| reference time | Reference timestamp. |
| clock offset | Offset of our clock to synchronized peer. |
| root delay | Total delay along path to root clock. |
| root dispersion | Dispersion of root path. |
| peer dispersion | Dispersion of synchronized peer. |
Use the show processes EXEC command to display information about the active processes.
show processes [cpu]| cpu | (Optional) Displays detailed CPU utilization statistics. |
EXEC
The following is sample output from the show processes command:
Router# show processes
CPU utilization for five seconds: 0%/0%; one minute: 0%; five minutes: 0%
PID Q T PC Runtime (ms) Invoked uSecs Stacks TTY Process
1 M T 40FD4 1736 58 29931 910/1000 0 Check heaps
2 H E 9B49C 68 585 116 790/900 0 IP Input
3 M E AD4E6 0 737 0 662/1000 0 TCP Timer
4 L E AEBB2 0 2 0 896/1000 0 TCP Protocols
5 M E A2F9A 0 1 0 852/1000 0 BOOTP Server
6 L E 4D2A0 16 127 125 876/1000 0 ARP Input
7 L E 50C76 0 1 0 936/1000 0 Probe Input
8 M E 63DA0 0 7 0 888/1000 0 MOP Protocols
9 M E 86802 0 2 0 1468/1500 0 Timers
10 M E 7EBCC 692 64 10812 794/1000 0 Net Background
11 L E 83BBC 0 5 0 870/1000 0 Logger
12 M T 11C454 0 38 0 574/1000 0 BGP Open
13 H E 7F0E0 0 1 0 446/500 0 Net Input
14 M T 436EA 540 3435 157 737/1000 0 TTY Background
15 M E 11BA9C 0 1 0 960/1000 0 BGP I/O
16 M E 11553A 5100 1367 3730 1250/1500 0 IGRP Router
17 M E 11B76C 88 4200 20 1394/1500 0 BGP Router
18 L T 11BA64 152 14650 10 942/1000 0 BGP Scanner
19 M * 0 192 80 2400 1714/2000 0 Exec
The following is sample output from the show processes cpu command:
Router# show processes cpu
CPU utilization for five seconds: 5%/2%; one minute: 3%; five minutes: 2%
PID Runtime (ms) Invoked uSecs 5Sec 1Min 5Min Process
1 1736 58 29931 0% 0% 0% Check heaps
2 68 585 116 1% 1% 0% IP Input
3 0 744 0 0% 0% 0% TCP Timer
4 0 2 0 0% 0% 0% TCP Protocols
5 0 1 0 0% 0% 0% BOOTP Server
6 16 130 123 0% 0% 0% ARP Input
7 0 1 0 0% 0% 0% Probe Input
8 0 7 0 0% 0% 0% MOP Protocols
9 0 2 0 0% 0% 0% Timers
10 692 64 10812 0% 0% 0% Net Background
11 0 5 0 0% 0% 0% Logger
12 0 38 0 0% 0% 0% BGP Open
13 0 1 0 0% 0% 0% Net Input
14 540 3466 155 0% 0% 0% TTY Background
15 0 1 0 0% 0% 0% BGP I/O
16 5100 1367 3730 0% 0% 0% IGRP Router
17 88 4232 20 2% 1% 0% BGP Router
18 152 14650 10 0% 0% 0% BGP Scanner
19 224 99 2262 0% 0% 1% Exec
Table 5-25 describes significant fields shown in the two displays.
| Field | Description |
|---|---|
| PID | Process ID. |
| Q | Process queue priority. Possible values: H (high), M (medium), L (low). |
| T | Scheduler test. Possible values: E (event), T (time), S (suspended). |
| PC | Current program counter. |
| Runtime (ms) | CPU time the process has used, in milliseconds. |
| Invoked | Number of times the process has been invoked. |
| uSecs | Microseconds of CPU time for each process invocation. |
| Stacks | Low water mark/Total stack space available. |
| TTY | Terminal that controls the process. |
| Process | Name of process. |
| five seconds | CPU utilization by task in last 5 seconds. |
| one minute | CPU utilization by task in last minute. |
| five minutes | CPU utilization by task in last 5 minutes. |
Description of first line: CPU utilization for the last 5 seconds, 1 minute, and 5 minutes. The second part of the 5-second figure is the percentage of the CPU used by interrupt routines.
Use the show processes memory EXEC command to show memory utilization.
show processes memoryThis command has no arguments or keywords.
EXEC
The following is sample output from the show processes memory command:
Router# show processes memory
Total: 2416588, Used: 530908, Free: 1885680
PID TTY Allocated Freed Holding Process
0 0 462708 2048 460660 *Init*
0 0 76 4328 - 4252 *Sched*
0 0 82732 33696 49036 *Dead*
1 0 2616 0 2616 Net Background
2 0 0 0 0 Logger
21 0 20156 40 20116 IGRP Router
4 0 104 0 104 BOOTP Server
5 0 0 0 0 IP Input
6 0 0 0 0 TCP Timer
7 0 360 0 360 TCP Protocols
8 0 0 0 0 ARP Input
9 0 0 0 0 Probe Input
10 0 0 0 0 MOP Protocols
11 0 0 0 0 Timers
12 0 0 0 0 Net Input
Table 5-26 describes significant fields shown in the display.
| Field | Description |
|---|---|
| Total | Total amount of memory held. |
| PID | Process ID. |
| TTY | Terminal that controls the process. |
| Allocated | Sum of all memory that process has requested from the system. |
| Freed | How much memory a process has returned to the system. |
| Holding | Allocated memory minus freed memory. A value can be negative when it has freed more than it was allocated. |
| Process | Process name. |
| *Init* | System initialization. |
| *Sched* | The scheduler. |
| *Dead* | Processes as a group that are now dead. |
Use the show protocols EXEC command to display the configured protocols.
This command shows the global and interface-specific status of any configured Level 3 protocol; for example, IP, DECnet, IPX, AppleTalk, and so forth.
show protocolsThis command has no arguments or keywords.
EXEC
The following is sample output from the show protocols command:
Router# show protocols
Global values:
Internet Protocol routing is enabled
DECNET routing is enabled
XNS routing is enabled
Appletalk routing is enabled
X.25 routing is enabled
Ethernet 0 is up, line protocol is up
Internet address is 131.108.1.1, subnet mask is 255.255.255.0
Decnet cost is 5
XNS address is 2001.AA00.0400.06CC
AppleTalk address is 4.129, zone Twilight
Serial 0 is up, line protocol is up
Internet address is 192.31.7.49, subnet mask is 255.255.255.240
Ethernet 1 is up, line protocol is up
Internet address is 131.108.2.1, subnet mask is 255.255.255.0
Decnet cost is 5
XNS address is 2002.AA00.0400.06CC
AppleTalk address is 254.132, zone Twilight
Serial 1 is down, line protocol is down
Internet address is 192.31.7.177, subnet mask is 255.255.255.240
AppleTalk address is 999.1, zone Magnolia Estates
For more information on the parameters or protocols shown in this sample output, see the Router Products Configuration Guide publication.
To list the current state of the queue lists, use the show queueing privileged EXEC command.
show queueing [custom | priority]| custom | (Optional) Shows status of custom queue lists. |
| priority | (Optional) Shows status of priority lists. |
Privileged EXEC
If no keyword is entered, this command show the status of both custom and priority queue lists.
The following is sample output from the show queueing custom EXEC command:
Router# show queueing custom
Current custom queue configuration:
List Queue Args
3 10 default
3 3 interface Tunnel3
3 3 protocol ip
3 3 byte-count 444 limit 3
custom-queue-list
priority-group
priority-list interface
priority-list queue-limit
priority-list stun
queue-list default
queue-list interface
queue-list protocol
queue-list queue byte-count
queue-list queue limit
queue-list stun
To check the status of communications between the SNMP agent and SNMP manager, use the
show snmp EXEC command.
This command has no arguments or keywords.
EXEC
This command provides counter information for RFC 1213 SNMP operations. It also displays the chassis ID string defined with the snmp-server chassis-id command.
The following is sample output from the show snmp command:
Router# show snmp
Chassis: SN#TS02K229
167 SNMP packets input
0 Bad SNMP version errors
0 Unknown community name
0 Illegal operation for community name supplied
0 Encoding errors
167 Number of requested variables
0 Number of altered variables
0 Get-request PDUs
167 Get-next PDUs
0 Set-request PDUs
167 SNMP packets output
0 Too big errors (Maximum packet size 484)
0 No such name errors
0 Bad values errors
0 General errors
167 Get-response PDUs
0 SNMP trap PDUs
Router#
snmp-server chassis-id
Use the show stacks EXEC command to monitor the stack utilization of processes and interrupt routines. Its display includes the reason for the last system reboot. If the system was reloaded because of a system failure, a saved system stack trace is displayed. This information is of use only to Cisco engineers analyzing crashes in the field. It is included here in case you need to read the displayed statistics to an engineer over the phone.
show stacksThis command has no arguments or keywords.
EXEC
The following is sample output from the show stacks command following a system failure:
Router# show stacks
Minimum process stacks:
Free/Size Name
652/1000 Router Init
726/1000 Init
744/1000 BGP Open
686/1200 Virtual Exec
Interrupt level stacks:
Level Called Free/Size Name
1 0 1000/1000 env-flash
3 738 900/1000 Multiport Communications Interfaces
5 178 970/1000 Console UART
System was restarted by bus error at PC 0xAD1F4, address 0xD0D0D1A
GS Software (GS3), Version 9.1(0.16), BETA TEST SOFTWARE
Compiled Tue 11-Aug-92 13:27 by jthomas
Stack trace from system failure:
FP: 0x29C158, RA: 0xACFD4
FP: 0x29C184, RA: 0xAD20C
FP: 0x29C1B0, RA: 0xACFD4
FP: 0x29C1DC, RA: 0xAD304
FP: 0x29C1F8, RA: 0xAF774
FP: 0x29C214, RA: 0xAF83E
FP: 0x29C228, RA: 0x3E0CA
FP: 0x29C244, RA: 0x3BD3C
To create or update an access policy, use the snmp-server access-policy global configuration command. To remove the specified access policy, use the no snmp-server access-policy command.
snmp-server access-policy destination-party source-party context privileges| destination-party | Name of a previously defined party identified as the destination party or target for this access policy. This name serves as a label used to reference a record defined for this party through the snmp-server party command. |
| source-party | Name of a previously defined party identified as the source party or subject for this access policy. This name serves as a label used to reference a record defined for this party through the snmp-server party command. |
| context | Name of a previously defined context that defines the resources for the access policy. This name serves as a label used to reference a record defined for this context through the snmp-server context command. |
| privileges | Bit mask representing the access privileges that govern the management operations that the source party can ask the destination party to perform. |
Global configuration
An access policy defines the management operations the destination party can perform in relation to resources defined by the specified context when requested by the source party. A destination party performs management operations that are requested by a source party. A source party sends communications to a destination party requesting the destination party to perform management operations. A context identifies object resources accessible to a party.
Access policies are defined on the router for communications from the manager to the agent; in this case, the agent is the destination party and the manager is the source party. Access policies can also be defined on the router for Response message and trap message communication from the agent to the manager; in this case, the manager is the destination party and the agent is the source party.
The privileges argument specifies the types of SNMP operations that are allowed between the two parties. There are seven types of SNMP operations.You specify the privileges as a bit mask representing the access privileges that govern the management operations that the source party can ask the destination party to perform. In other words, the bit mask identifies the commands that the source party can send to the destination party. You use decimal or hexadecimal format to specify privileges as a sum of values in which each value specifies an SNMP PDU type that the source party can use to request an operation. The decimal values are defined as follows:
To remove an access-policy entry, all three arguments specified as command arguments must match exactly the values of the entry to be deleted. A difference of one value constitutes a different access policy.
The first snmp-server command that you enter enables both versions of SNMP.
The following example configures an access policy providing the manager with read-only access to the agent:
snmp-server access-policy agt1 mgr1 ctx1 0x23
The following example configures an access policy providing the manager with read-write access to the agent:
snmp-server access-policy agt2 mgr2 ctx2 43
The following example configures an access policy that allows responses and SNMP v.2 traps to be sent from the agent to a management station:
snmp-server access-policy mgr1 agt1 ctx1 132
The following example removes the access policy configured for the destination party named agt1, the source party named mgr1, and with a context named ctx1.
no snmp-server access-policy agt1 mgr1 ctx1
snmp-server context
snmp-server party
To provide a message line identifying the SNMP server serial number, use the snmp-server chassis-id global configuration command. Use the no form of this command to restore the default value, if any.
snmp-server chassis-id text| text | Message you want to enter to identify the chassis serial number. |
On hardware platforms where the serial number can be machine read, the default is the serial number. For example, an AGS does not have a default value; a Cisco 7000 has a default value of its serial number.
Global configuration
The Cisco MIB provides a chassis MIB variable that enables the SNMP manager to gather data on system card descriptions, chassis type, chassis hardware version, chassis ID string, software version of ROM monitor, software version of system image in ROM, bytes of processor RAM installed, bytes of NVRAM installed, bytes of NVRAM in use, current configuration register setting, and the value of the configuration register at the next reload. The following installed card information is provided: type of card, serial number, hardware version, software version, and chassis slot number.
The chassis ID message can be seen with show snmp command.
In the following example, the chassis serial number specified is 1234456:
snmp-server chassis-id 1234456
show snmp
To set up the community access string to permit access to the SNMP v.1 protocol, use the snmp-server community global configuration command. The no snmp-server community command removes the specified community string.
snmp-server community string [RO | RW] [number]| string | Community string that acts like a password and permits access to the SNMP protocol. |
| RO | (Optional) Specifies read-only access. Authorized management stations are only able to retrieve MIB objects. |
| RW | (Optional) Specifies read-write access. Authorized management stations are able to both retrieve and modify MIB objects. |
| number | (Optional) Integer from 1 to 99 that specifies an access list of IP addresses that are allowed to use the community string to gain access to the SNMP v.1 agent. |
By default, an SNMP community string permits read-only access.
Global configuration
For the previous version of this command, the string argument was optional. The string argument is now required. However, to prevent errors and provide backward-compatibility, if the string option is omitted, a default value of public is assumed.
The no snmp-server command disables both versions of SNMP (SNMP v.1 and SNMP v.2).
The first snmp-server command that you enter enables both versions of SNMP.
The following example assigns the string comaccess to SNMP v.1 allowing read-only access and specifies that IP access list 4 can use the community string:
snmp-server community comaccess RO 4
The following example disables both versions of SNMP:
no snmp-server
snmp-server party
To set the system contact (syscontact) string, use the snmp-server contact global configuration command. Use the no form to remove the system contact information.
snmp-server contact text| text | String that describes the system contact information. |
No syscontact string is set.
Global configuration
The following is an example of a syscontact string:
snmp-server contact Dial System Operator at beeper # 27345
To create or update a context record, use the snmp-server context global configuration command. To remove a specific context entry, use the no snmp-server context command.
snmp-server context context-name context-oid view-name| context-name | Name of the context to be created or updated. This name serves as a label used to reference a record for this context. |
| context-oid | Object identifier to assign to the context. Specify this value in dotted decimal notation, with an optional text identifier; for example, 1.3.6.1.6.3.3.1.4.131.108.45.11.1(== initialContextId.131.108.45.11.1). |
| view-name | Name of a previously defined view. The view defines the objects available to the context. |
Global configuration
A context record identifies object resources accessible to a party. A context record is one of the components that make up an access policy. Therefore, you must configure a context record before you can create an access policy that includes the context. Context records and party records further codify MIB views.
To remove a context entry, specify only the name of the context. The name identifies the context to be deleted.
The first snmp-server command that you enter enables both versions of SNMP.
The following example shows how to create a context that includes all objects in the MIB-II subtree using a previously defined view named mib2:
snmp-server context mycontext initialContextid.131.108.24.56.3 mib2
A dagger (+) indicates that the command is documented in another chapter.
snmp-server view
write memory+
write terminal+
To specify the recipient of an SNMP trap operation, use the snmp-server host global configuration command. The no snmp-server host command removes the specified host.
snmp-server host address community-string [snmp] [tty]| address | Name or Internet address of the host. |
| community-string | Password-like community string to send with the trap operation. |
| snmp | (Optional) Enables the SNMP traps defined in RFC 1157. |
| tty | (Optional) Enables Cisco enterprise-specific traps when a TCP connection closes. |
If neither the snmp or tty keywords are supplied, the default is to enable both trap types.
Global configuration
The snmp-server host command specifies which host or hosts should receive SNMP traps. You need to issue the snmp-server host command once for each host acting as a trap recipient. When multiple snmp-server host commands are given, the community string in the last command is used, and in general, the trap types set in the last command will be used for all SNMP trap operations.
The following example sends the SNMP traps defined in RFC 1157 to the host specified by the name cisco.com. The community string is defined as the string comaccess.
snmp-server host cisco.com comaccess snmp
The following example sends the SNMP and Cisco enterprise-specific traps to address 131.108.2.160:
snmp-server host 131.108.2.160
snmp-server trap-timeout
To set the system location string, use the snmp-server location global configuration command. Use the no form of this command to remove the location string.
snmp-server location text| text | String that describes the system location information |
No system location string is set.
Global configuration
The following example illustrates a system location string:
snmp-server location Building 3/Room 214
To establish control over the largest SNMP packet size permitted when the SNMP server is receiving a request or generating a reply, use the snmp-server packetsize global configuration command. Use the no form of this command to restore the default value.
snmp-server packetsize byte-count| byte-count | Integer byte count from 484 to 8192 |
484 bytes
Global configuration
The following example establishes a packet filtering of a maximum size of 1024 bytes:
snmp-server packetsize 1024
To create or update a party record, use the snmp-server party global configuration command. To remove a specific party entry, use the no snmp-server party command.
snmp-server party party-name party-oid [protocol-address] [packetsize size]| party-name | Name of the party characterized by the contents of the record. This name serves as a label used to reference the party record that you are creating or modifying. |
| party-oid | Object identifier to assign to the party. Specify this value in dotted decimal notation, with an optional text identifier; for example, 1.3.6.1.6.3.3.1.3.131.108.34.54.1 (= initialPartyId.131.108.34.54.1) |
| protocol-address | (Optional) Address of the protocol that the party record pertains to. Currently the only supported protocol is UDP, so this value specifies a UDP address in the format a.b.c.d port.
In future releases, additional protocols will be supported.
This value is used to specify the destination of trap messages. |
| packetsize size | (Optional) Maximum size in bytes of a message that this party is able to receive. By default, the packet size set through the snmp-server packetsize command is used. |
| local | remote | (Optional) Indicates that the party is local or remote. If neither local nor remote is specified, a default value of local is assumed. |
| authentication | (Optional) Indicates that the party uses an authentication protocol. If specified, either md5 or snmpv1 is required. |
| md5 key | Indicates that the party uses the Message Digest algorithm MD5 for message authentication. If md5 is specified, you must also specify a 16-byte hexadecimal ASCII string representing the MD5 authentication key for the party. All messages sent to this party will be authenticated using the SNMP v.2 MD5 authentication method with the key specified by key. |
| clock clock | (Optional) Initial value of the authentication clock. |
| lifetime lifetime | (Optional) Lifetime, in seconds, that represents the upper bound on acceptable delivery delay for messages generated by the party. |
| snmpv1 string | Community string. The keyword snmpv1 indicates that the party uses community-based authentication. All messages sent to this party will be authenticated using the SNMP v.1 community string specified by string instead of MD5. |
If neither local nor remote is specified to indicate the location of the party, the party is assumed to be local.
If you do not specify a packet size, the packet size set through the snmp-server packetsize command is used.
Global configuration
You define parties to identify managers and agents. An SNMP v.2 party identity is unique; it includes the logical network location of the party, characterized by the transport protocol domain and transport addressing information, and, optionally, an authentication method and its arguments.The authentication protocol reliably identifies the origin of all messages sent by the party. The authentication protocol also ensures the integrity of the messages; in other words, it ensures that the message received is the message that was sent.
Specifying md5 as the authentication method implies that this party record pertains to an SNMP v.2 party.
Specifying snmpv1 as the authentication method implies that this party record pertains to an SNMP v.1 party. This allows a management station that supports only SNMP v.1 to use SNMP v.2 MIB views. Instead of using the snmp-server community command, you can use the snmp-server party command with the snmpv1 keyword to define an SNMP v.1 party to be used to communicate with an SNMP v.1 management station. The snmp-server community command does not allow you to create MIB views for an SNMP v.1 management station.
If authentication is not specified, the party record pertains to an SNMP v.2 party, and no authentication will be performed for messages sent to this party.
To remove a party record, specify only the name of the party. The name identifies the party to be deleted.
The first snmp-server command that you enter enables both versions of SNMP.
The following example configures a remote unauthenticated party:
snmp-server party mgr1 initialPartyId.131.108.45.32.3 udp 131.108.45.76 162
The following example configures a local MD5-authenticated party with a large maximum packet size. You enter this command as a single line:
snmp-server party agt1 initialPartyId.131.108.45.32.4 packetsize 1500 local
authentication md5 23de457623900ac3ef568fcb236589 lifetime 400
The following example configures an SNMP v.1 proxy party for the community public:
snmp-server party proxyv1 initialPartyId.131.108.45.32.100 authentication snmpv1 public
The following example removes the party named mgr1:
no snmp-server party mgr1
A dagger (+) indicates that the command is documented in another chapter.
snmp-server community
write memory+
write terminal+
To establish the message queue length for each trap host, use the snmp-server queue-length global configuration command. This command defines the length of the message queue for each trap host. Once a trap message is successfully transmitted, software will continue to empty the queue, but never faster than at a rate of four trap messages per second.
snmp-server queue-length length| length | Integer that specifies the number of trap events that can be held before the queue must be emptied |
10 events
Global configuration
The following example establishes a message queue that traps four events before it must be emptied:
snmp-server queue-length 4
To use the SNMP message reload feature, the device configuration must include the snmp-server system-shutdown global configuration command. The no snmp-server system-shutdown option prevents an SNMP system-shutdown request (from an SNMP manager) from resetting the Cisco agent.
snmp-server system-shutdownThis command has no arguments or keywords.
This command is not included in the configuration file.
Global configuration
The following example illustrates how to include the SNMP message reload feature in the device configuration:
snmp-server system-shutdown
To establish trap message authentication, use the snmp-server trap-authentication global configuration command. To remove message authentication, use the no snmp-server trap-authentication command.
snmp-server trap-authentication [snmpv1 | snmpv2]| snmpv1 | (Optional) Indicates that SNMP authentication traps will be sent to SNMP v.1 management stations only. |
| snmpv2 | (Optional) Indicates that SNMP authentication traps will be sent to SNMP v.2 management stations only. |
Specifying the snmp-server trap-authentication command without a keyword turns on trap message authentication. In this case, messages are sent to the host that is specified though the snmp-server host command and to any SNMP stations configured through access policies to receive trap messages.
Global configuration
Specify the snmpv1 or snmpv2 keyword to indicate the type of management stations to send the trap messages to.
This command enables the router as an agent to send a trap message when it receives an SNMP v.1 packet with an incorrect community string or an SNMP v.2 packet with an incorrect MD5 authentication key.
The SNMP specification requires that a trap message be generated for each packet with an incorrect community string or authentication key; however, because this action can result in a security breach, the router (as an agent) by default does not send a trap message when it receives an incorrect community string or authentication key.
The community string or key is checked before any access list that may be set, so it is possible to get spurious trap messages. In other words, if you have issued an snmp-server community command with a specified access list, you might receive messages that come from someone that is not on the access list; in this case, an authentication trap is issued.The only workarounds are to disable trap authentication or to configure an access list on a router between the SNMP agent and the SNMP manager to prevent packets from getting to the SNMP agent.
To turn off all message authentication traps, use the no snmp-server trap-authentication without a keyword. To turn off message authentication traps only for SNMP v.1 stations or only for SNMP v.2 stations, give the negative form of the command with the appropriate keyword.
The first snmp-server command that you enter enables both versions of SNMP.
The following example illustrates how to enter the command that establishes trap message authentication:
snmp-server trap-authentication
snmp-server host
To specify the interface (and hence the corresponding IP address) that an SNMP trap should originate from, use the snmp-server trap-source global configuration command. Use the no form of the command to remove the source designation.
snmp-server trap-source interface| interface | Interface from which the SNMP trap originates. The argument includes the interface type and number in platform-specific syntax. |
No interface is specified.
Global configuration
When an SNMP trap is sent from a Cisco SNMP server, it has a trap address of whatever interface it happened to go out of at that time. Use this command if you want to use the trap address to trace particular needs.
The following example specifies that the IP address for interface Ethernet 0 is the source for all traps on the router:
snmp-server trap-source ethernet 0
The following example specifies that the IP address for interface Ethernet 2/1 on a Cisco 7000 is the source for all traps on the router:
snmp-server trap-source ethernet 2/1
To define how often to try resending trap messages on the retransmission queue, use the snmp-server trap-timeout global configuration command.
snmp-server trap-timeout seconds| seconds | Integer that sets the interval, in seconds, for resending the messages |
30 seconds
Global configuration
Before the router tries to send a trap, it looks for a route to the destination address. If there is no known route, the trap is saved in a retransmission queue. The server trap-timeout command determines the number of seconds between retransmission attempts.
The following example sets an interval of 20 seconds to try resending trap messages on the retransmission queue:
snmp-server trap-timeout 20
snmp-server host
To create or update an SNMP v.2 security context using the simplified security conventions method, use the snmp-server userid global configuration command. The no snmp-server userid command removes the specified security context.
snmp-server userid user-id [view view-name] [RO | RW] [password password]| user-id | User ID name that identifies an approved SNMP v.2 user. The user ID represents a set of security information for this user. This value can identify a particular user of the system or a background process. |
| view view-name | (Optional) View to be used for this security context. The argument view-name must be the name of a predefined view. For authenticated users, defaults to the predefined view everything. For users who are not authenticated, defaults to the predefined view restricted. |
| RO | (Optional) Specifies read-only access.This is the default for unauthenticated users. |
| RW | (Optional) Specifies read-write access. This is the default for authenticated users. |
| password password | (Optional) Indicates that this is an authenticated user, and defines the password used to authenticate the user. The password must be at least eight characters long. |
For the snmp-server userid command, the default value for the view-name argument depends on whether the security context is password protected. Depending on whether the security context is password protected, one of the following default values applies:
These predefined views are described in RFC 1447.
Read-only access is the default for unauthenticated users.
Read-write access is the default for authenticated users.
Global configuration
The snmp-server userid command implements the simplified security conventions method of configuring the relationship between an agent and a manager. It provides a single-step method that offers an alternative to the access policy configuration method of defining this relationship. The simplified method offers ease-of-use at the cost of forfeiting control over certain values that can be configured if you create an access policy. The simplified security conventions method applies to a configuration in which the agent is the destination or recipient of messages and the manager is the source or sender of messages. You cannot use this command to define a relationship in which the agent is the source and the manager is the destination. The security context created does not apply to trap messages.
| Caution Use the simplified security conventions method only if the management station participating in the manager-agent relationship also supports this method. |
If you provide a password, the password is encrypted on write operations for which encryption is enabled.
If you use the snmp-server userid command, the SNMP v.2 implementation assumes default values that it determines internally for required information that you cannot provide through the command interface. SNMP v.2 uses the following methods to determine these values:
The first snmp-server command that you enter enables both versions of SNMP.
The following example configures a security context for the user harold, who is unauthenticated, uses the view default, and has read-only access:
snmp-server userid harold
snmp-server access-policy
snmp-server context
snmp-server party
snmp-server view
To create or update a view entry, use the snmp-server view global configuration command. To remove the specified SNMP server view entry, use the no snmp-server view command.
snmp-server view view-name oid-tree {included | excluded}| view-name | Label for the view record that you are updating or creating. The name is used to reference the record. |
| oid-tree | Object identifier of the ASN.1 subtree to be included or excluded from the view. To identify the subtree, specify a text string consisting of numbers, such as 1.3.6.2.4, or a word, such as system. Replace a single subidentifier with the asterisk (*) wildcard to specify a subtree family; for example 1.3.*.4. |
| included | excluded | Type of view. You must specify either included or excluded. |
Global configuration
Other SNMP v.2 commands require a view as an argument. You use this command to create a view to be used as arguments for other commands that create records including a view.
Two standard predefined views can be used when a view is required, instead of defining a view. One is everything, which indicates that the user can see all objects. The other is restricted, which indicates that the user can see three groups: system, snmpStats, and snmpParties. The predefined views are described in RFC 1447.
The first snmp-server command that you enter enables both versions of SNMP.
The following example creates a view that includes all objects in the MIB-II subtree:
snmp-server view mib2 mib-2 included
The following example creates a view that includes all objects in the MIB-II system group and all objects in the Cisco enterprise MIB:
snmp-server phred system included
snmp-server view phred cisco included
The following example creates a view that includes all objects in the MIB-II system group except for sysServices (System 7) and all objects for interface 1 in the MIB-II interfaces group:
snmp-server view agon system included
snmp-server view agon system.7 excluded
snmp-server view agon ifEntry.*.1 included
A dagger (+) indicates that the command is documented in another chapter.
snmp-server context
snmp-server userid
write memory+
write terminal+
To control the number of login attempts that can be made on a line set up for TACACS verification, use the tacacs-server attempts global configuration command. Use the no tacacs-server attempts command to remove this feature and restore the default.
tacacs-server attempts count| count | Integer that sets the number of attempts |
Three attempts
Global configuration
The following example changes the login attempt to just one try:
tacacs-server attempts 1
To specify that the network or router must indicate whether the user may perform an action when the user attempts to perform the action, use the tacacs-server authenticate global configuration command.
tacacs-server authenticate {connection [always] | enable | slip [always] [access-lists]}| connection | Configures a required response when a user makes a TCP connection. |
| enable | Configures a required response when a user enters the enable command. |
| slip | Configures a required response when a user starts a SLIP or PPP session. |
| always | (Optional) Performs authentication even when a user is not logged in. This option only applies to the connection or slip keywords. |
| access-lists | (Optional) Requests and installs access lists. This option only applies to the slip keyword. |
Global configuration
Enter one of the keywords to specify the action (when a user makes a TCP connection, for example).
If you use the enable use-tacacs command, you must also use tacacs-server authenticate enable, or else you will be locked out of the router.
The following example illustrates how to configure TACACS logins that authenticate user TCP connections:
tacacs-server authenticate connect
enable use-tacacs
To enable an extended TACACS mode, use the tacacs-server extended global configuration command. Use the no tacacs-server extended command to disable the mode.
tacacs-server extendedThis command has no arguments or keywords.
Disabled
Global configuration
The following is an example of how to enable extended TACACS mode:
tacacs-server extended
To specify a TACACS host, use the tacacs-server host global configuration command. You can use multiple tacacs-server host commands to specify multiple hosts. The software searches for the hosts in the order you specify them. The no tacacs-server host command deletes the specified name or address.
tacacs-server host name| name | Name or Internet address of the host |
No TACACS host is specified.
Global configuration
The following example illustrates how to specify a TACACS host named SCACAT:
tacacs-server host SCACAT
A dagger (+) indicates that the command is documented in another chapter.
login tacacs +
ppp +
slip +
To cause the network server to request the privileged password as verification, or to force successful login without further input from the user, use the tacacs-server last-resort global configuration command. The no tacacs-server last-resort command restores the system to the default behavior.
tacacs-server last-resort {password | succeed}| password | Allows the user to access the EXEC command mode by entering the password set by the enable command. |
| succeed | Allows the user to access the EXEC command mode without further question. |
If, when running the TACACS server, the TACACS server does not respond, the default action is to deny the request.
Global configuration
Use the tacacs-server last-resort command to be sure that login can occur; for example, when a systems administrator needs to log in to troubleshoot TACACS servers that might be down.
The following example illustrates how to force successful login:
tacacs-server last-resort succeed
A dagger (+) indicates that the command is documented in another chapter.
enable password
login (exec) +
Use the tacacs-server notify global configuration command to cause a message to be transmitted to the TACACS server, with retransmission being performed by a background process for up to 5 minutes. The terminal user, however, receives an immediate response allowing access to the feature specified. Enter one of the keywords to specify notification of the TACACS server upon the corresponding action (when user logs out, for example).
tacacs-server notify {connection | enable | logout}| connection | Specifies that a message be transmitted when a user makes a TCP connection. |
| enable | Specifies that a message be transmitted when a user enters the enable command. |
| logout | Specifies that a message be transmitted when a user logs out. |
No message is transmitted to the TACACS server.
Global configuration
The following example sets up notification of the TACACS server when a user logs out:
tacacs-server notify logout
To specify that the first TACACS request to a TACACS server be made without password verification, use the tacacs-server optional-passwords global configuration command. Use the no form of this command to restore the default.
tacacs-server optional-passwordsThis command has no arguments or keywords.
Disabled
Global configuration
When the user types in the login name, the login request is transmitted with the name and a zero-length password. If accepted, the login procedure completes. If the TACACS server refuses this request, the server software prompts for a password and tries again when the user supplies a password. The TACACS server must support authentication for users without passwords to make use of this feature. This feature supports all TACACS requests--login, SLIP, enable, and so on.
The following example illustrates how to configure the first login to not require TACACS verification:
tacacs-server optional-passwords
To specify the number of times the router software will search the list of TACACS server hosts before giving up, use the tacacs-server retransmit global configuration command. The router software will try all servers, allowing each one to timeout before increasing the retransmit count. The no tacacs-server retransmit command restores the default.
tacacs-server retransmit retries| retries | Integer that specifies the retransmit count |
Two retries
Global configuration
The following example specifies a retransmit counter value of five times:
tacacs-server retransmit 5
To set the interval that the server waits for a server host to reply, use the tacacs-server timeout global configuration command. The no tacacs-server timeout command restores the default.
tacacs-server timeout seconds| seconds | Integer that specifies the timeout interval in seconds |
5 seconds
Global configuration
The following example changes the interval timer to 10 seconds:
tacacs-server timeout 10
To test Flash memory on MCI and envm Flash EPROM interfaces, use the test flash EXEC command.
test flashThis command has no arguments or keywords.
EXEC
The following example illustrates how to begin the interface test:
test flash
To test the system interfaces on the modular router, use the test interfaces EXEC command.
test interfacesThis command has no arguments or keywords.
EXEC
The test interfaces EXEC command is intended for the factory checkout of network interfaces. It is not intended for diagnosing problems with an operational router. The test interfaces output does not report correct results if the router is attached to a "live" network. For each network interface that has an IP address that can be tested in loopback (MCI and ciscoBus Ethernet and all serial interfaces), the test interfaces command sends a series of ICMP echoes. Error counters are examined to determine the operational status of the interface.
The following example illustrates how to begin the interface test:
test interfaces
To perform a test of Multibus memory (including nonvolatile memory) on the modular router, use the test memory EXEC command.
test memoryThis command has no arguments or keywords.
EXEC
| Caution The memory test overwrites memory. If you use the test memory command, you will need to rewrite nonvolatile memory. For example, if you test Multibus memory, which is the memory used by the CSC-R 4-Mbps Token Ring interfaces, you will need to reload the system before the network interfaces will operate properly. The test memory command is intended primarily for use by Cisco personnel. |
The following example illustrates how to begin the memory test:
test memory
Use the trace EXEC command to discover the IP routes the router's packets will actually take when traveling to their destination.
trace [protocol] [destination]| protocol | (Optional) Protocols that can be used are appletalk, clns, ip and vines. |
| destination | (Optional) Destination address or host name on the command line. The default parameters for the appropriate protocol are assumed and the tracing action begins. |
The protocol argument is based on the router's examination of the format of the destination argument. For example, if the router finds a destination in IP format, the protocol defaults to ip.
EXEC
The trace command works by taking advantage of the error messages generated by routers when a datagram exceeds its time-to-live (TTL) value.
The trace command starts by sending probe datagrams with a TTL value of one. This causes the first router to discard the probe datagram and send back an error message. The trace command sends several probes at each TTL level and displays the round-trip time for each.
The trace command sends out one probe at a time. Each outgoing packet may result in one or two error messages. A time exceeded error message indicates that an intermediate router has seen and discarded the probe. A destination unreachable error message indicates that the destination node has received the probe and discarded it because it could not deliver the packet. If the timer goes off before a response comes in, trace prints an asterisk (*).
The trace command terminates when the destination responds, when the maximum TTL is exceeded, or when the user interrupts the trace with the escape sequence. By default, to invoke the escape sequence, press Ctrl-^ X--which is done by simultaneously pressing the Ctrl, Shift, and 6 keys, letting go, then pressing the X key.
Due to bugs in the IP implementation of various hosts and routers, the IP trace command may behave in odd ways.
Not all destinations will respond correctly to a probe message by sending back an ICMP port unreachable message. A long sequence of TTL levels with only asterisks, terminating only when the maximum TTL has been reached, may indicate this problem.
There is a known problem with the way some hosts handle an ICMP TTL exceeded message. Some hosts generate an ICMP message but they reuse the TTL of the incoming packet. Since this is zero, the ICMP packets do not make it back. When you trace the path to such a host, you may see a set of TTL values with asterisks (*). Eventually the TTL gets high enough that the ICMP message can get back. For example, if the host is six hops away, trace will time out on responses 6 through 11.
The following display shows sample IP trace output when a destination host name has been specified:
Router# trace ip ABA.NYC.mil
Type escape sequence to abort.
Tracing the route to ABA.NYC.mil (26.0.0.73)
1 DEBRIS.CISCO.COM (131.108.1.6) 1000 msec 8 msec 4 msec
2 BARRNET-GW.CISCO.COM (131.108.16.2) 8 msec 8 msec 8 msec
3 EXTERNAL-A-GATEWAY.STANFORD.EDU (192.42.110.225) 8 msec 4 msec 4 msec
4 BB2.SU.BARRNET.NET (131.119.254.6) 8 msec 8 msec 8 msec
5 SU.ARC.BARRNET.NET (131.119.3.8) 12 msec 12 msec 8 msec
6 MOFFETT-FLD-MB.in.MIL (192.52.195.1) 216 msec 120 msec 132 msec
7 ABA.NYC.mil (26.0.0.73) 412 msec 628 msec 664 msec
Table 5-27 describes the fields shown in the display.
| Field | Description |
|---|---|
| 1 | Indicates the sequence number of the router in the path to the host. |
| DEBRIS.CISCO.COM | Host name of this router. |
| 131.108.1.61 | Internet address of this router. |
| 1000 msec 8 msec 4 msec | Round-trip time for each of the three probes that are sent. |
Table 5-28 describes the characters that can appear in trace output.
| Char | Description |
|---|---|
| nn msec | For each node, the round-trip time in milliseconds for the specified number of probes. |
| * | The probe timed out. |
| ? | Unknown packet type. |
| Q | Source quench. |
| P | Protocol unreachable. |
| N | Network unreachable. |
| U | Port unreachable. |
| H | Host unreachable. |
trace (privileged)
Use the trace EXEC command to discover the routes the router's packets will actually take when traveling to their destination.
trace [protocol] [destination]| protocol | (Optional) Protocols that can be used are appletalk, clns, ip and vines. |
| destination | (Optional) Destination address or host name on the command line. The default parameters for the appropriate protocol are assumed and the tracing action begins. |
protocol is based on the router's examination of the format of destination. For example, if the router finds a destination in IP format, the protocol defaults to ip.
Privileged EXEC
The trace command works by taking advantage of the error messages generated by routers when a datagram exceeds its time-to-live (TTL) value.
The trace command starts by sending probe datagrams with a TTL value of one. This causes the first router to discard the probe datagram and send back an error message. The trace command sends several probes at each TTL level and displays the round-trip time for each.
The trace command sends out one probe at a time. Each outgoing packet may result in one or two error messages. A time exceeded error message indicates that an intermediate router has seen and discarded the probe. A destination unreachable error message indicates that the destination node has received the probe and discarded it because it could not deliver the packet. If the timer goes off before a response comes in, trace prints an asterisk (*).
The trace command terminates when the destination responds, when the maximum TTL is exceeded, or when the user interrupts the trace with the escape sequence. By default, to invoke the escape sequence, press Ctrl-^ X--which is done by simultaneously pressing the Ctrl, Shift, and 6 keys, letting go, then pressing the X key.
To use nondefault parameters and invoke an extended trace test, enter the command without a destination argument. You will be stepped through a dialog to select the desired parameters.
Due to bugs in the IP implementation of various hosts and routers, the IP trace command may behave in odd ways.
Not all destinations will respond correctly to a probe message by sending back an ICMP port unreachable message. A long sequence of TTL levels with only asterisks, terminating only when the maximum TTL has been reached, may indicate this problem.
There is a known problem with the way some hosts handle an ICMP TTL exceeded message. Some hosts generate an ICMP message but they reuse the TTL of the incoming packet. Since this is zero, the ICMP packets do not make it back. When you trace the path to such a host, you may see a set of TTL values with asterisks (*). Eventually the TTL gets high enough that the ICMP message can get back. For example, if the host is six hops away, trace will time out on responses 6 through 11.
The following display shows sample IP trace output when a destination host name has been specified:
Router# trace ABA.NYC.mil
Type escape sequence to abort.
Tracing the route to ABA.NYC.mil (26.0.0.73)
1 DEBRIS.CISCO.COM (131.108.1.6) 1000 msec 8 msec 4 msec
2 BARRNET-GW.CISCO.COM (131.108.16.2) 8 msec 8 msec 8 msec
3 EXTERNAL-A-GATEWAY.STANFORD.EDU (192.42.110.225) 8 msec 4 msec 4 msec
4 BB2.SU.BARRNET.NET (131.119.254.6) 8 msec 8 msec 8 msec
5 SU.ARC.BARRNET.NET (131.119.3.8) 12 msec 12 msec 8 msec
6 MOFFETT-FLD-MB.in.MIL (192.52.195.1) 216 msec 120 msec 132 msec
7 ABA.NYC.mil (26.0.0.73) 412 msec 628 msec 664 msec
Table 5-29 describes the fields shown in the display.
| Field | Description |
|---|---|
| 1 | Indicates the sequence number of the router in the path to the host. |
| DEBRIS.CISCO.COM | Host name of this router. |
| 131.108.1.6 | Internet address of this router. |
| 1000 msec 8 msec 4 msec | Round-trip time for each of the three probes that are sent. |
The following display shows a sample trace session involving the extended dialog of the trace command.
Router# trace
Protocol [ip]:
Target IP address: mit.edu
Source address:
Numeric display [n]:
Timeout in seconds [3]:
Probe count [3]:
Minimum Time to Live [1]:
Maximum Time to Live [30]:
Port Number [33434]:
Loose, Strict, Record, Timestamp, Verbose[none]:
Type escape sequence to abort.
Tracing the route to MIT.EDU (18.72.2.1)
1 ICM-DC-2-V1.ICP.NET (192.108.209.17) 72 msec 72 msec 88 msec
2 ICM-FIX-E-H0-T3.ICP.NET (192.157.65.122) 80 msec 128 msec 80 msec
3 192.203.229.246 540 msec 88 msec 84 msec
4 T3-2.WASHINGTON-DC-CNSS58.T3.ANS.NET (140.222.58.3) 84 msec 116 msec 88 msec
5 T3-3.WASHINGTON-DC-CNSS56.T3.ANS.NET (140.222.56.4) 80 msec 132 msec 88 msec
6 T3-0.NEW-YORK-CNSS32.T3.ANS.NET (140.222.32.1) 92 msec 132 msec 88 msec
7 T3-0.HARTFORD-CNSS48.T3.ANS.NET (140.222.48.1) 88 msec 88 msec 88 msec
8 T3-0.HARTFORD-CNSS49.T3.ANS.NET (140.222.49.1) 96 msec 104 msec 96 msec
9 T3-0.ENSS134.T3.ANS.NET (140.222.134.1) 92 msec 128 msec 92 msec
10 W91-CISCO-EXTERNAL-FDDI.MIT.EDU (192.233.33.1) 92 msec 92 msec 112 msec
11 E40-RTR-FDDI.MIT.EDU (18.168.0.2) 92 msec 120 msec 96 msec
12 MIT.EDU (18.72.2.1) 96 msec 92 msec 96 msec
Table 5-30 describes the fields that are unique to the extended trace sequence, as shown in the display.
| Field | Description |
|---|---|
| Target IP address | You must enter a host name or an IP address. There is no default. |
| Source address | One of the interface addresses of the router to use as a source address for the probes. The router will normally pick what it feels is the best source address to use. |
| Numeric display | The default is to have both a symbolic and numeric display; however, you can suppress the symbolic display. |
| Timeout in seconds | The number of seconds to wait for a response to a probe packet. The default is 3 seconds. |
| Probe count | The number of probes to be sent at each TTL level. The default count is 3. |
| Minimum Time to Live [1] | The TTL value for the first probes. The default is 1, but it can be set to a higher value to suppress the display of known hops. |
| Maximum Time to Live [30] | The largest TTL value that can be used. The default is 30. The trace command terminates when the destination is reached or when this value is reached. |
| Port Number | The destination port used by the UDP probe messages. The default is 33434. |
| Loose, Strict, Record, Timestamp, Verbose | IP header options. You can specify any combination. The trace command issues prompts for the required fields. Note that trace will place the requested options in each probe; however, there is no guarantee that all routers (or end nodes) will process the options. |
| Loose | Allows you to specify a list of nodes that must be traversed when going to the destination. |
| Strict | Allows you to specify a list of nodes that must be the only nodes traversed when going to the destination. |
| Record | Allows you to specify the number of hops to leave room for. |
| Timestamp | Allows you to specify the number of time stamps to leave room for. |
| Verbose | If you select any option, the verbose mode is automatically selected and trace prints the contents of the option field in any incoming packets. You can prevent verbose mode by selecting it again, toggling its current setting. |
Table 5-31 describes the characters that can appear in trace output.
| Char | Description |
|---|---|
| nn msec | For each node, the round-trip time in milliseconds for the specified number of probes. |
| * | The probe timed out. |
| ? | Unknown packet type. |
| Q | Source quench. |
| P | Protocol unreachable. |
| N | Network unreachable. |
| U | Port unreachable. |
| H | Host unreachable. |
trace (user)
To establish a username-based authentication system at login, even though your network cannot support a TACACS service, use the username global configuration command.
username name [nopassword | password encryption-type password]| name | Host name, server name, user ID, or command name. The name argument must be one word. White spaces and quotation marks are not allowed. |
| nopassword | (Optional) No password is required for this user to log in. This is usually most useful in combination with the autocommand keyword. |
| password | (Optional) Specifies a possibly encrypted password for this username. |
| encryption-type | (Optional) Single-digit number that defines whether the text immediately following is encrypted, and, if so, what type of encryption is used. Currently defined encryption types are 0, which means that the text immediately following is not encrypted, and 7, which means that the text is encrypted with a Cisco-defined encryption algorithm. |
| password | (Optional) A password can contain embedded spaces and must be the last option specified in the username command. |
| secret | For CHAP authentication, the secret for the local router or the remote device. The secret is encrypted when it is stored on the local router. This prevents the secret from being stolen. The secret can consist of any string of up to 11 printable ASCII characters. You can specify any number of username/password combinations, thus allowing authentication of any number of remote devices. |
| access-class | (Optional) Specifies an outgoing access list that overrides the access list specified in the access-class line configuration command. It is used for the duration of the user's session. |
| number | (Optional) Access list number. |
| autocommand | (Optional) Causes the specified command to be issued automatically after the user logs in. When the command is complete, the session is terminated. Because the command can be any length and can contain imbedded spaces, commands using the autocommand keyword must be the last option on the line. |
| command | (Optional) Command string. |
| noescape | (Optional) Prevents a user from using an escape character on the host to which that user is connected. |
| nohangup | (Optional) Prevents the communication server from disconnecting the user after an automatic command (set up with the autocommand keyword) has completed. Instead, the user gets another login prompt. |
None
Global configuration
The username command provides username/password authentication for login purposes only. (Note that the username command does not provide username/password authentication for enable mode when the enable use-tacacs command is also used.)
Multiple username commands can be used to specify options for a single user.
Add a username entry for each remote system that the local router communicates with and requires authentication from. The remote device must have a username entry for the local router. This entry must have the same password as the local router's entry for that remote device.
This command can be useful for defining usernames that get special treatment, for example, an "info" username that does not require a password, but connects the user to a general-purpose information service.
The username command is also required as part of the configuration for the Challenge Handshake Authentication Protocol (CHAP). For each remote system that the local router communicates with and requires authentication from, add a username entry.
If no secret is specified and debug serial-interface is enabled, an error is displayed when a link is established and the CHAP challenge is not implemented. To obtain debugging information on CHAP, use the debug serial-interface and debug serial-packet commands. For more information about debug commands, refer to the Debug Command Reference publication.
The following example implements a service similar to the UNIX who command, which lists the current users of the router:
username who nopassword nohangup autocommand show users
The following example implements an information service that does not require use of a password:
username info nopassword noescape autocommand telnet nic.ddn.mil
The following example implements an ID that works even if the TACACS servers all fail:
username superuser password superpassword
The following example configuration enables CHAP on interface serial 0. It also defines a password for the local server, Adam, and a remote server, Eve.
hostname Adam
interface serial 0
encapsulation ppp
ppp authentication chap
username Adam password oursystem
username Eve password theirsystem
When you look at your configuration file, the passwords are encrypted and the display looks similar to the following:
hostname Adam
interface serial 0
encapsulation ppp
ppp authentication chap
username Adam password 7 1514040356
username Eve password 7 121F0A18
hostname
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