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Table of Contents

Interface Configuration Commands

Interface Configuration Commands

This chapter contains the commands used to configure nonprotocol-specific interface features. The commands are in alphabetical order. For hardware technical descriptions and for information about installing the communication server interfaces, refer to the hardware installation and maintenance publication for your product.

For interface configuration tasks and examples, refer to the Access and Communication Servers Configuration Guide.

backup delay

To define how much time should elapse before a secondary line is set up or taken down after a primary line transition, use the backup delay interface configuration command. Use the no form of this command to remove the definition.

backup delay {enable-delay | never} {disable-delay | never}
no backup delay {enable-delay | never} {disable-delay | never}
Syntax Description
enable-delay Integer argument that specifies the delay in seconds after the primary line goes down before the secondary line is activated
disable-delay Integer argument that specifies the delay in seconds after the primary line goes up before the secondary line is deactivated
never Keyword that is specified to prevent the secondary line from being activated or deactivated
Default

A secondary line is never activated nor deactivated.

Command Mode

Interface configuration

Usage Guidelines

When a primary line goes down, the communication server delays the number of seconds defined by the enable-delay argument before enabling the secondary line. If, after the delay period, the primary line is still down, the secondary line is activated.

When a primary line comes back up, the communication server will delay by the number of seconds defined by the disable-delay argument.

In cases where there are spurious signal disruptions that might appear as intermittent lost carrier signals, it is recommended that some delay be enabled before activating and deactivating a secondary.

The interval configured with the backup delay command does not affect the operation of the backup load command.

Example

The following example sets a 10-second delay on deactivating the secondary line; however, the line is activated immediately:

interface serial 0 backup delay 0 10

backup interface

To configure the serial interface as a secondary, or dial backup line, use the backup interface interface configuration command. Use the no form of this command with the appropriate serial port designation to turn this feature off.

backup interface interface-name
no backup interface interface-name
Syntax Description
interface-name or type Serial port to be set as the secondary interface line
Default

None

Command Mode

Interface configuration

Example

The following example sets serial interface 1 as the backup line to serial interface 0:

interface serial 0 backup interface serial 1
Related Command

down-when-looped

backup load

To set the traffic load thresholds for dial backup service, use the backup load interface configuration command. Use the no form of this command to remove the setting.

backup load {enable-threshold | never} {disable-load | never}
no backup load {
enable-threshold | never} {disable-load | never}
Syntax Description
enable-threshold Integer argument that specifies a percentage of the primary line's available bandwidth
disable-load Integer argument that specifies a percentage of the primary line's available bandwidth
never Keyword that sets the secondary line to never be activated due to load
Default

The secondary line is never activated due to load.

Command Mode

Interface configuration

Usage Guidelines

When the transmitted or received load on the primary line is greater than the value assigned to the enable-threshold argument, the secondary line is enabled.

When the transmitted load on the primary line plus the transmitted load on the secondary line is less than the value entered for the disable-load argument, and the received load on the primary line plus the received load on the secondary line is less than the value entered for the disable-load argument, the secondary line is disabled.

If the never keyword is used instead of an enable-threshold value, the secondary line is never activated because of load. If the never keyword is used instead of an disable-load value, the secondary line is never deactivated because of load.

Example

The following example sets the traffic load threshold to 60 percent on the primary line. When that load is exceeded, the secondary line is activated, and will not be deactivated until the combined load is less than 5 percent of the primary bandwidth.

interface serial 0 backup load 60 5

bandwidth

To set a bandwidth value for an interface, use the bandwidth interface configuration command. Use the no form of this command to restore the default values.

bandwidth kilobits
no bandwidth
Syntax Description
kilobits Intended bandwidth in kilobits per second. For a full bandwidth DS3, enter the value 44736.
Default

Default bandwidth values are set during startup.

Command Mode

Interface configuration

Usage Guidelines

Bandwidth values can be displayed with the EXEC command show interfaces.

The bandwidth command sets an informational parameter only; you cannot adjust the actual bandwidth of an interface with this command. For some media, such as Ethernet, the bandwidth is fixed; for other media, such as serial lines, you can change the actual bandwidth by adjusting hardware. For both classes of media, you can use the bandwidth configuration command to communicate the current bandwidth to the higher-level protocols.

Additionally, IGRP uses the minimum path bandwidth to determine a routing metric. The TCP protocol adjusts initial retransmission parameters based on the apparent bandwidth of the outgoing interface.

At higher bandwidths, the value you configure with the bandwidth command is not what is displayed by the show interface command. The value shown is that used in IGRP updates and also used in computing load.


Note This is a routing parameter only; it does not affect the physical interface.
Example

The following example sets the full bandwidth for DS3 transmissions:

interface serial 0 bandwidth 44736

clear counters

To clear the interface counters, use the clear counters EXEC command.

clear counters [type number]
Syntax Description
type (Optional) Specifies the interface type; it is one of the keywords listed in Table 6-1.
number (Optional) Specifies the interface counter displayed with the show interfaces command.

Clear Counters Interface Type Keywords
Keyword Interface Type
async Asynchronous serial interface
dialer Dialer interface
ethernet Ethernet interface
loopback Loopback interface
null Null interface
serial Synchronous serial interface
tokenring Token Ring interface
tunnel Tunnel interface
Command Mode

EXEC

Usage Guidelines

This command clears all the current interface counters from the interface unless the optional arguments type-keyword and number are specified to clear only a specific interface type (serial, Ethernet, Token Ring, and so on).


Note This command will not clear counters retrieved using SNMP, but only those seen with the EXEC show interface command.
Example

The following example illustrates how to clear all interface counters:

cs# clear counters
Related Command

show interfaces

clear interface

To reset the hardware logic on an interface, use the clear interface EXEC command.

clear interface type number
Syntax Description
type Specifies the interface type; it is one of the keywords listed in Table 6-2.
number Specifies the port, connector, or interface card number.

Clear Interface Type Keywords
Keyword Interface Type
async Asynchronous serial interface
ethernet Ethernet interface
loopback Loopback interface
null Null interface
serial Synchronous serial interface
tokenring Token Ring interface
tunnel Tunnel interface
Command Mode

EXEC

Usage Guidelines

Under normal circumstances, you do not need to clear the hardware logic on interfaces.

Example
cs# clear interface async 1

clear line

To return a line to its idle state, enter the clear line privileged EXEC command at the system prompt.

clear line line-number
Syntax Description
line-number Asynchronous line port number assigned with the interface async command
Command Mode

Privileged EXEC

Usage Guidelines

Normally, this command returns the line to its conventional function as a terminal line, with the interface left in a "down" state.

Example

The following example shows how to use the clear line command to return serial interface 5 to its idle state:

clear line 5

clear snapshot quiet-time

To end the quiet period on a client router within two minutes, use the clear snapshot quiet-time EXEC command.

clear snapshot quiet-time interface
Syntax Description
interface Interface type and number.
Command Mode

EXEC

Usage Guidelines

The clear snapshot quiet-time command places the client router in a state to reenter the active period withing two minutes. The two-minute hold period ensures a quiet period of at least two minutes between active periods.

Example

The following example ends the quiet period on dialer interface 1:

clear snapshot quiet-time dialer 1
Related Commands

show snapshot
snapshot client

clockrate

To configure the clock rate for appliques (connector hardware) on the serial interface of the MCI and SCI cards to an acceptable bit rate, use the clockrate interface configuration command. Use the no form of this command to remove the clock rate if you change the interface from a DCE to a DTE device.

clockrate bps
no clockrate
Syntax Description
bps Desired clock rate in bits per second: 1200, 2400, 4800, 9600, 19200, 34800, 56000, 64000, 72000, 125000, 148000, 500000, 800000, 1000000, 1300000, 2000000, or 4000000
Default

No clock rate

Command Mode

Interface configuration

Usage Guidelines

Be aware that the fastest speeds might not work if your cable is too long, and that speeds faster than 148,000 bits per second are too fast for RS-232 signaling. It is recommended that you only use the synchronous serial RS-232 signal at speeds up to 64,000 bits per second. To permit a faster speed, use an RS-449 or V.35 applique.

Example

The following example sets the clock rate on the first serial interface to 64,000 bits per second:

interface serial 0 clockrate 64000

compress predictor

To configure point-to-point software compression for a LAPB, use the compress predictor interface configuration command. Use the no form of this command to disable compression.

compress predictor
no compress predictor
Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

You can configure point-to-point software compression for all LAPB encapsulations. Compression reduces the size of LAPB frames via lossless data compression. The compression algorithm used is a predictor algorithm (the RAND compression algorithm), which uses a compression dictionary to predict what the next character in the frame will be.

Compression is performed in software and can significantly affect system performance. We recommend that you disable compression if CPU load exceeds 65%. To display the CPU load, use the show process cpu EXEC command.

Compression requires that both ends of the serial link be configured to use compression. You should never enable compression for connections to a public data network.


Note The best performance data compression algorithms adjust their compression methodology as they discover patterns in the data. For this to work well, no data can be lost, so the compression algorithm is run over LAPB to ensure that everything is sent in order, with no missing data and no duplicate data.

If the majority of your traffic is already compressed files, you should not use compression.

When using compression, you should adjust the MTU for the serial interface and the LAPB N1 parameter as shown in the example to avoid informational diagnostics regarding excessive MTU or N1 sizes.

Example

The following example enables compression on serial interface 0 for a LAPB link:

interface serial 0 encapsulation lapb compress predictor mtu 1509 lapb n1 12072
Related Commands

A dagger (+) indicates that the command is documented in another chapter.

encapsulation lapb +
encapsulation lapb-dce +
encapsulation multi-lapb +
encapsulation multi-lapb-dce +
encapsulation x25 +
show compress
show processes
+

delay

To set a delay value for an interface, use the delay interface configuration command. Use the no form of this command to restore the default delay value.

delay tens-of-microseconds
no delay
Syntax Description
tens-of-microseconds Integer that specifies the delay in tens of microseconds for an interface or network segment
Default

You can display default delay values with the EXEC command show interfaces.

Command Mode

Interface configuration

Example

The following example sets a 30,000-microsecond delay on serial interface 3:

interface serial 3 delay 30000
Related Command

show interfaces

description

To add a description to an interface configuration, use the description interface configuration command. Use the no form of this command to remove the description.

description string
no description
Syntax Description
string Comment or description to help you remember what is attached to this interface
Default

None

Command Mode

Interface configuration

Usage Guidelines

The description command is meant solely as a comment to be put in the configuration to help you remember what certain interfaces are used for. The description appears in the output of the following EXEC commands: show configuration, show interfaces, and write terminal.

Example

The following example describes a 3174 controller on serial interface 0:

interface serial 0 description 3174 Controller for test lab
Related Commands

A dagger (+) indicates that the command is documented in another chapter.

show configuration +
show interfaces
write terminal
+

down-when-looped

To configure an interface to inform the system it is down when loopback is detected, use the
down-when-looped interface configuration command.

down-when-looped
Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command is valid for PPP encapsulation on serial and HSSI interfaces.

When an interface has a backup interface configured, it is often desirable that the backup interface be enabled when the primary interface is either down or in loopback. By default, the backup is only enabled if the primary interface is down. By using the down-when-looped command, the backup interface will also be enabled if the primary interface is in loopback.

If testing an interface with the loopback command, or by placing the DCE into loopback, down-when-looped should not be configured; otherwise packets will not be transmitted out the interface that is being tested.

Example

In the following example, serial interface 0 is configured for PPP encapsulation. It is then configured to let the system know that it is down when in loopback mode.

interface serial 0 encapsulation ppp down-when-looped
Related Commands

backup interface
loopback

early-token-release

To enable early token release, use the early-token-release interface configuration command. Use the no form of this command to disable this feature.

early-token-release
no early-token-release
Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This feature helps to increase the total bandwidth of the Token Ring. Early token release is a method whereby the Token Ring interfaces can release the token back onto the ring immediately after transmitting rather than waiting for the frame to return.

The CSC-R16M, CSC-2R, and CSC-1R cards support early token release.

Example

The following example enables the use of early token release on Token Ring interface 1:

interface tokenring 1 early-token-release

encapsulation

To set the encapsulation method used by the interface, use the encapsulation interface configuration command.

encapsulation encapsulation-type
Syntax Description
encapsulation-type

Encapsulation type. See Table 6-3 for a list of supported encapsulation types.

Table 6-3: Encapsulation Types
Keyword Encapsulation Type
arpa This encapsulation uses a 16-bit protocol type code.
bfex25 Blacker Front End Encryption X.25 operation (for serial interface)
ddnx25-dce DDN X.25 DCE operation (for serial interface)
ddnx25 DDN X.25 DTE operation (for serial interface)
frame-relay Frame Relay (for serial interface)
hdlc High-Level Data Link Control (HDLC) protocol for serial interface. This encapsulation method provides the synchronous framing and error detection functions of HDLC without windowing or retransmission.
sap IEEE 802.3 encapsulation. In this encapsulation, the type code becomes the frame length for the IEEE 802.2 LLC encapsulation (destination and source Service Access Points and a control byte).
lapb X.25 LAPB DTE operation (for serial interface)
lapb-dce X.25 LAPB DCE operation (for serial interface)
multip-lapb X.25 LAPB multiprotocol DTE operation (for serial interface)
multi-lapb-dce X.25 LAPB multiprotocol DCE operation (for serial interface)
ppp Point-to-Point Protocol (PPP) (for serial interface)
smds Switched Multimegabit Data Services (SMDS) (for serial interface)
snap IEEE 802.2 Ethernet media. This encapsulation is specified in RFC 1042 and allows Ethernet protocols to run on IEEE 802.2 media.
x25-dce X.25 DCE operation (for serial interface)
x25 X.25 DTE operation (for serial interface)
Default

The default depends on the type of interface. For example, an Ethernet interface defaults to ARPA.

Command Mode

Interface configuration

Examples

The following example reenables standard Ethernet Version 2.0 encapsulation on Ethernet interface 0:

interface ethernet 0 encapsulation arpa

The following example sets IEEE 802.3 encapsulation on Ethernet interface 1:

interface ethernet 1 encapsulation sap

The following example enables PPP encapsulation on serial interface 0:

interface serial 0 encapsulation ppp

The following example sets IEEE 802.2 encapsulation on Ethernet interface 1:

interface ethernet 1 encapsulation snap
Related Commands

A dagger (+) indicates that the command is documented in another chapter.

keepalive
ppp +
ppp authentication chap
slip +

error-threshold

To set the mechanism that protects against packet overload and resulting recount errors on the MCI interface cards, use the error-threshold interface configuration command.

error-threshold milliseconds
Syntax Description
milliseconds Frequency at which the error recount will be set in milliseconds
Default

1000 milliseconds

Command Mode

Interface configuration

Example

The following commands set the error recount threshold on Ethernet interface 2 to 10,000 milliseconds:

interface ethernet 2 error-threshold 10000

hold-queue

To specify the hold-queue limit of an interface, use the hold-queue interface configuration command. Use the no form of this command with the appropriate keyword to restore the default values for an interface.

hold-queue length {in | out}
no hold-queue {in | out}
Syntax Description
length An integer that specifies the maximum number of packets in the queue
in A keyword that specifies the input queue
out A keyword that specifies the output queue
Default

The default input hold-queue limit is 75 packets. The default output hold-queue limit is 40 packets. These limits prevent a malfunctioning interface from consuming an excessive amount of memory. There is no fixed upper limit to a queue size.

Command Mode

Interface configuration

Usage Guidelines

The input hold queue prevents a single interface from flooding the network server with too many input packets. Further input packets are discarded if the interface has too many input packets outstanding in the system.

If priority output queueing is being used, the length of the four output queues is set using the priority-list global configuration command. The hold-queue command cannot be used to set an output hold queue length in this situation.

For slow links, use a small output hold-queue limit. This approach prevents storing packets at a rate that exceeds the transmission capability of the link. For fast links, use a large output hold-queue limit. A fast link may be busy for a short time (and thus require the hold queue), but can empty the output hold queue quickly when capacity returns.

To display the current hold queue setting and the number of packets discarded because of hold queue overflows, use the EXEC command show interfaces.


Note Increasing the hold queue can have detrimental effects on network routing and response times. For protocols that use seq/ack packets to determine round trip times, do not increase the output queue. Dropping packets instead informs hosts to slow down transmissions to match available bandwidth. This is generally better than having duplicate copies of the same packet within the network (which can happen with large hold queues).
Example

The following example illustrates how to set a small input queue on a slow serial line:

interface serial 0 hold-queue 30 in
Related Command

show interfaces

ignore-dcd

Use the ignore-dcd interface configuration command to configure the serial interface to monitor the DSR signal (instead of the DCD signal) as the line up/down indicator. Use the no form of this command to restore the default behavior.

ignore-dcd
no ignore-dcd
Syntax Description

This command has no arguments or keywords.

Default

The serial interface, operating in DTE mode, monitors the DCD signal as the line up/down indicator.

Command Mode

Interface configuration

Usage Guidelines

This command applies to Quad Serial NIM interfaces on the Cisco 4000 series and Hitachi-based serial interfaces on the Cisco 2500 series and Cisco 3000 series.

When the serial interface is operating in DTE mode, it monitors the Data Carrier Detect (DCD) signal as the line up/down indicator. By default, the attached DCE device sends the DCD signal. When the DTE interface detects the DCD signal, it changes the state of the interface to up.

In some configurations, such as an SDLC multidrop environment, the DCE device sends the Data Set Ready (DSR) signal instead of the DCD signal, which prevents the interface from coming up. Use this command to tell the interface to monitor the DSR signal as the line up/down indicator instead of the DCD signal.

Example

The following example configures serial interface 0 to monitor the DSR signal as the line up/down indicator:

interface serial 0 ignore-dcd

interface

To configure an interface type and enter interface configuration mode, use the interface global configuration command.

interface type number

To configure a subinterface, use the interface global configuration command.

interface type number.subinterface-number [multipoint | point-to-point]

Syntax Description
type Type of interface to be configured. See Table 6-4.
number Port, connector, or interface card number. The numbers are assigned at the factory at the time of installation or when added to a system, and can be displayed with the show interfaces command.
.subinterface-number Subinterface number in the range 1 to 4294967293. The number that precedes the period (.) must match the number to which this subinterface belongs.
multipoint | point-to-point (Optional) Specifies a multipoint or point-to-point subinterface. Default is multipoint.

Interface Type Keywords
Keyword Interface Type
async Line used as an asynchronous interface.
dialer Dialer interface.
ethernet Ethernet IEEE 802.3 interface.
loopback Software-only loopback interface that emulates an interface that is always up. It is a virtual interface supported on all platforms. The interface-number is the number of the loopback interface that you want to create or configure.There is no limit on the number of loopback interfaces you can create.
null Null interface.
serial Serial interface.
tokenring Token Ring interface.
tunnel Tunnel interface; a virtual interface. The interface-number is the number of the tunnel interface that you want to create or configure. There is no limit on the number of tunnel interfaces you can create.
Default

The default mode for subinterfaces is multipoint.

Command Mode

Global configuration

Usage Guidelines

Subinterfaces can be configured to support partially meshed Frame Relay networks and multiple IPX encapsulations on LAN media (refer to the Access and Communication Servers Configuration Guide).

Examples

In the following example, serial interface 0 is configured with PPP encapsulation:

interface serial 0 encapsulation ppp

The following example enables loopback mode and assigns an IP network address and network mask to the interface. The loopback interface established here will always appear to be up:

interface loopback 0 ip address 131.108.1.1 255.255.255.0

The following example shows how a partially meshed Frame Relay network can be configured. In this example, subinterface serial 0.1 is configured as a multipoint subinterface with three Frame Relay PVCs associated, and subinterface serial 0.2 is configured as a point-to-point subinterface.

interface serial 0 encapsulation frame-relay interface serial 0.1 multipoint ip address 131.108.10.1 255.255.255.0 frame-relay interface-dlci 42 broadcast frame-relay interface-dlci 53 broadcast interface serial 0.2 point-to-point ip address 131.108.11.1 255.255.0 frame-relay interface-dlci 59 broadcast
Related Commands

A dagger (++) indicates that the command is documented in the Cisco Access Connection Guide.

ppp ++
show interfaces
slip ++

interface dialer

To designate a dialer rotary group leader, use the interface dialer global configuration command.

interface dialer interface-number
Syntax Description
interface-number Integer that you select to indicate a dialer rotary group in the range 0 to 9
Default

None

Command Mode

Global configuration

Usage Guidelines

Dialer rotary groups allow you to apply a single interface configuration to a set of interfaces. Once the interface configuration is propagated to a set of interfaces, those interfaces can be used to place calls using the standard dial-on-demand criteria. When many destinations are configured, any of these interfaces can be used for outgoing calls.

Dialer rotary groups are useful in environments that require many calling destinations. Only the rotary group needs to be configured with all of the dialer map commands. The only configuration required for the interfaces is the dialer rotary-group command indicating that each interface is part of a dialer rotary group.

Although a dialer rotary group is configured as an interface, it is not a physical interface. Instead it represents a group of interfaces. Any number of dialer groups can be defined.

Interface configuration commands entered after the interface dialer command will be applied to all physical interfaces assigned to specified rotary group.

Example

The following example identifies dialer interface 1 as the dialer rotary group leader. Dialer interface 1 is not a physical interface, but represents a group of interfaces. The interface configuration commands that follow apply to all interfaces included in this group.

interface dialer 1 encapsulation ppp dialer in-band dialer map ip 131.108.2.5 username YYY 14155553434 dialer map ip 131.126.4.5 username ZZZ
Related Command

A dagger (+) indicates that the command is documented in another chapter.

dialer rotary-group +

keepalive

Use the keepalive interface configuration command to set the keepalive timer for a specific interface. The no keepalive command turns off keepalives entirely.

keepalive [seconds]
no keepalive [seconds]
Syntax Description
seconds (Optional) Unsigned integer value greater than 0. The default is 10 seconds.
Default

10 seconds

Command Mode

Interface configuration

Usage Guidelines

You can configure the keepalive interval, which is the frequency at which the communication server sends messages to itself (Ethernet and Token Ring) or to the other end (serial), to ensure a network interface is alive. The interval in previous software versions was 10 seconds; it is now adjustable in 1-second increments down to 1 second. An interface is declared down after three update intervals have passed without receiving a keepalive packet.

Setting the keepalive timer to a low value is very useful for rapidly detecting Ethernet interface failures (transceiver cable disconnecting, cable unterminated, and so on).

A typical serial line failure involves losing Carrier Detect (CD). Since this sort of failure is typically noticed within a few milliseconds, adjusting the keepalive timer for quicker routing recovery is generally not useful.


Note When adjusting the keepalive timer for a very low bandwidth serial interface, large datagrams can delay the smaller keepalive packets long enough to cause the line protocol to go down. You might need to experiment to determine the best value.
Example

The following example sets the keepalive interval to 3 seconds:

interface ethernet 0 keepalive 3

loopback

To diagnose equipment malfunctions between an interface and a device, use the loopback interface configuration command. Use the no form of this command to disable the test.

loopback
no loopback
Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

On MCI and SCI serial interface cards, the loopback functions when a CSU/DSU or equivalent device is attached to the communication server. The loopback command loops the packets through the CSU/DSU to configure a CSU loop, when the device supports this feature.

On the MCI and MEC Ethernet cards, the interface receives back every packet it sends when the loopback command is enabled. Loopback operation has the additional effect of disconnecting network server functionality from the network.

On all Token Ring interface cards (except the 4-megabit CSC-R card), the interface receives back every packet it sends when the loopback command is enabled. Loopback operation has the additional effect of disconnecting network server functionality from the network.

Example

The following example configures the loopback test on Ethernet interface 4:

interface ethernet 4 loopback
Related Command

down-when-looped

loopback dte

To loop packets to DTE internally within the CSU/DSU at the DTE interface, use the loopback interface configuration command. Use the no form of this command to remove the loop.

loopback dte
no loopback dte
Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Example

The following example configures the loopback test on the DTE interface:

interface serial 1 loopback dte

loopback line

To loop packets completely through the CSU/DSU to configure the CSU loop, use the loopback line interface configuration command. Use the no form of this command to remove the loop.

loopback line
no loopback line
Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command is useful for testing the DCE device (CSU/DSU) itself.

To show interfaces currently in loopback operation, use the show interfaces loopback EXEC command.

Example

The following example configures the loopback test on the DCE device:

interface serial 1 loopback line
Related Command
show interfaces loopback

loopback remote

To loop packets completely through the CSU/DSU, over the DS3 link, to the remote CSU/DSU and back, use the loopback remote interface configuration command. Use the no form of this command to remove the loop.

loopback remote
no loopback remote
Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command is useful for testing the DCE device (CSU/DSU) itself.

This command applies only when the device supports the remote function. It is used for testing the data communication channels. The loopback usually is performed at the line port, rather than the DTE port, of the remote CSU/DSU.

To show interfaces currently in loopback operation, use the show interfaces loopback EXEC command.

Example

The following example configures a remote loopback test:

interface serial 0 loopback remote
Related Command
show interfaces loopback

mop enabled

To enable an interface to support the Maintenance Operation Protocol (MOP), use the mop enabled interface configuration command. Use the no form of this command to disable MOP on an interface.

mop enabled
no mop enabled
Syntax Description

This command has no arguments or keywords.

Default

Enabled by default on Ethernet interfaces and disabled on all other interfaces.

Command Mode

Interface configuration

Example

In the following example, MOP is enabled for serial interface 0:

interface serial 0 mop enabled
Related Commands

A dagger (+) indicates that the command is documented in another chapter.

mop sysid
mop restransmit-timer
+
mop retries +

mop sysid

To enable an interface to send out periodic Maintenance Operation Protocol (MOP) system identification messages, use the mop sysid interface configuration command. Use the no form of this command to disable MOP message support on an interface.

mop sysid
no mop sysid
Syntax Description

This command has no arguments or keywords.

Default

Enabled

Command Mode

Interface configuration

Usage Guidelines

You can run MOP without having the background system ID messages sent. This lets you use the MOP remote console, but does not generate messages used by the configurator.

Example

In the following example, serial interface 0 is enabled to send MOP system identification messages:

interface serial0 mop sysid
Related Commands

A dagger (+) indicates that the command is documented in another chapter.

mop device-code +
mop enabled

mtu

To adjust the maximum packet size or maximum transmission unit (MTU) size, use the mtu interface configuration command. Use the no form of this command to restore the MTU value to its original default value.

mtu bytes
no mtu
Syntax Description
bytes Desired size in bytes
Default

Table 6-5 lists default MTU values according to media type.


Default Media MTU Values
Media Type Default MTU
Ethernet 1500
Serial 1500
Token Ring 4464
Command Mode

Interface configuration

Usage Guidelines

Each interface has a default maximum packet size or maximum transmission unit (MTU) size. This number generally defaults to the largest size possible for that type interface. On serial interfaces, the MTU size varies, but cannot be set smaller than 64 bytes.


Note Changing the MTU value with the mtu interface configuration command can affect values for the protocol-specific versions of the command (ip mtu for example). If the values specified with the ip mtu interface configuration command is the same as the value specified with the mtu interface configuration command, and you change the value for the mtu interface configuration command, the ip mtu value automatically matches the new mtu interface configuration command value. However, changing the values for the ip mtu configuration commands has no effect on the value for the mtu interface configuration command.
Example

The following example specifies an MTU of 1000 bytes:

interface serial 1 mtu 1000
Related Commands

A dagger (+) indicates that the command is documented in another chapter.

encapsulation smds +
ip mtu +

ppp authentication

To enable Challenge Handshake Authentication Protocol (CHAP) or Password Authentication Protocol (PAP) on a serial interface, use the ppp authentication interface configuration command. Use the no form of this command to disable this encapsulation.

ppp authentication {chap | pap} [if-needed]
no ppp authentication
Syntax Description
chap Enables CHAP on a serial interface.
pap Enables PAP on a serial interface.
if-needed (Optional) Do not perform CHAP or PAP authentication if user has already provided authentication. This option is available only on asynchronous interfaces.
Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

Once you have enabled CHAP or PAP, the local communication server requires a password from remote devices. If the remote device does not support CHAP or PAP, no traffic will be passed to that device.

If you are using autoselect on a tty line, you will probably want to use the ppp authentication command to turn on PPP authentication for the corresponding interface.

When you specify the if-needed option, PPP authentication will not be required when the user has already provided authentication. This option is useful in conjunction to the autoselect command.

Example

The following example enables CHAP on asynchronous interface 4:

interface async 4 encapsulation ppp ppp authentication chap
Related Commands

A dagger (+) indicates that the command is documented in another chapter.

autoselect+
encapsulation ppp
+
ppp use-tacacs+
username
+

ppp quality

To enable Link Quality Monitoring (LQM) on a serial interface, use the ppp quality interface configuration command. Use the no form of this command to disable LQM.

ppp quality percentage
no ppp quality
Syntax Description
percentage Specifies the link quality threshold. The range is 1 to 100.
Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

The percentages are calculated for both incoming and outgoing directions. The outgoing quality is calculated by comparing the total number of packets and bytes sent to the total number of packets and bytes received by the peer. The incoming quality is calculated by comparing the total number of packets and bytes received to the total number of packets and bytes sent by the peer.

If the link quality percentage is not maintained, the link is deemed to be of poor quality and is taken down. The policy implements a time lag so that the link does not bounce up and down.

Example

The following example enables LQM on serial interface 0:

interface serial 0 encapsulation ppp ppp quality 80
Related Commands

A dagger (+) indicates that the command is documented in another chapter.

encapsulation ppp
keepalive
+

pulse-time

To enable pulsing DTR signal intervals on the serial interfaces, use the pulse-time interface configuration command. Use the no form of this command to restore the default interval.

pulse-time seconds
no pulse-time
Syntax Description
seconds Integer that specifies the DTR signal interval in seconds
Default

0 seconds

Command Mode

Interface configuration

Usage Guidelines

When the serial line protocol goes down (for example, because of loss of synchronization) the interface hardware is reset and the DTR signal is held inactive for at least the specified interval. This function is useful for handling encrypting or other similar devices that use the toggling of the DTR signal to resynchronize.

Example

The following example enables DTR pulse signals for three seconds on serial interface 0:

interface serial 0 pulse-time 3

ring-speed

To set the ring speed for the CSC-1R and CSC-2R Token Ring interfaces, use the ring-speed interface configuration command.

ring-speed speed
Syntax Description
speed Integer that specifies the ring speed, either 4 for 4-Mbps or 16 for 16-Mbps operation
Default

16-Mbps operation

Command Mode

Interface configuration

Usage Guidelines
Caution Configuring a ring speed that is wrong or incompatible with the connected Token Ring will cause the ring to beacon, which effectively takes the ring down and makes it nonoperational.
Example

The following example sets a Token Ring interface ring speed to 4 Mbps:

interface tokenring 0 ring-speed 4

scheduler-interval

To control the maximum amount of time that can elapse without running the lowest priority system processes, use the scheduler-interval global configuration command. Use the no form of this command to restore the default.

scheduler-interval milliseconds
no scheduler-interval
Syntax Description
milliseconds An integer that specifies the interval in milliseconds. The minimum interval that you can specify is 500 milliseconds; there is no maximum value.
Default

The default is to allow high-priority operations to use as much of the central processor as needed.

Command Mode

Global configuration

Usage Guidelines

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.

Example

The following example changes the low-priority process schedule to an interval of 750 milliseconds:

scheduler-interval 750

show async status

To list the status of asynchronous interfaces, use the show async status EXEC command:

show async status
Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Usage Guidelines

This command shows all asynchronous sessions, whether they are using SLIP or PPP encapsulation.

Sample Display

The following is sample output from the show async status command:

cs> show async status Async protocol statistics: Rcvd: 5448 packets, 7682760 bytes 1 format errors, 0 checksum errors, 0 overrun, 0 no buffer Sent: 5455 packets, 7682676 bytes, 0 dropped Int Local Remote Qd InPack OutPac Inerr Drops MTU Qsz 1 192.31.7.84 Dynamic 0 0 0 0 0 1500 10

Table 6-6 describes significant fields shown in the display.


Asynchronous Statistics Display Field Descriptions
Field Description
Rcvd Statistics on packets received.
5548 packets Packets received.
7682760 bytes Total number of bytes.
1 format errors Packets with a bad IP header, even before the checksum is calculated.
0 checksum errors Count of checksum errors.
0 overrun Number of giants received.
0 no buffer Number of packets received when no buffer was available.
Sent Statistics on packets sent.
5455 packets Packets sent.
7682676 bytes Total number of bytes.
0 dropped Number of packets dropped.
Int Interface number.
* Line currently in use.
Local Local IP address on the link.
Remote Remote IP address on the link; "Dynamic" indicates that a remote address is allowed but has not been specified; "None" indicates that no remote address is assigned or being used.
Qd Number of packets on hold queue (Qsz is max).
InPack Number of packets received.
OutPac Number of packets sent.
Inerr Number of total input errors; sum of format errors, checksum errors, overruns and no buffers.
Drops Number of packets received that would not fit on the hold queue.
MTU Current maximum transmission unit size.
Qsz Current output hold queue size.
Related Command

interface async

show compress

To display compression statistics on a serial interface, use the show compress EXEC command.

show compress
Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Sample Display

The following is sample output from the show compress command:

cs# show compress Serial0 uncompressed bytes xmt/rcv 10710562/11376835 1 min avg ratio xmt/rcv 2.773/2.474 5 min avg ratio xmt/rcv 4.084/3.793 10 min avg ratio xmt/rcv 4.125/3.873 no bufs xmt 0 no bufs rcv 0 resets 0

Table 6-7 describes the fields shown in the display.


Show Compress Field Descriptions
Field Description
Serial0 Name and number of the interface
uncompressed bytes xmt/rcv Total number of uncompressed bytes sent and received
1 min avg ratio xmt/rcv
5 min avg ratio xmt/rcv
10 min avg ratio xmt/rcv
Static compression ratio for bytes sent and received, averaged over 1, 5, and 10 minutes
no bufs xmt Number of times buffers were not available to compress data being sent
no bufs rcv Number of times buffers were not available to uncompress data being received
resets Number of resets
Related Command

compress predictor

show controllers ethernet

Use the show controllers ethernet EXEC command to display information on the Cisco 2500.

show controllers ethernet interface-number
Syntax Description
interface-number Interface number of the Ethernet interface.
Command Mode

EXEC

Sample Display

The following is sample output from the show controllers ethernet command:

cs# show controllers ethernet 0 LANCE unit 0, NIM slot 1, NIM type code 4, NIM version 1 Media Type is 10BaseT, Link State is Up, Squelch is Normal idb 0x4060, ds 0x5C80, regaddr = 0x8100000 IB at 0x600D7AC: mode=0x0000, mcfilter 0000/0001/0000/0040 station address 0000.0c03.a14f default station address 0000.0c03.a14f buffer size 1524 RX ring with 32 entries at 0xD7E8 Rxhead = 0x600D8A0 (12582935), Rxp = 0x5CF0(23) 00 pak=0x60336D0 ds=0x6033822 status=0x80 max_size=1524 pak_size=98 01 pak=0x60327C0 ds=0x6032912 status=0x80 max_size=1524 pak_size=98 02 pak=0x6036B88 ds=0x6036CDA status=0x80 max_size=1524 pak_size=98 03 pak=0x6041138 ds=0x604128A status=0x80 max_size=1524 pak_size=98 04 pak=0x603FAA0 ds=0x603FBF2 status=0x80 max_size=1524 pak_size=98 05 pak=0x600DC50 ds=0x600DDA2 status=0x80 max_size=1524 pak_size=98 06 pak=0x6023E48 ds=0x6023F9A status=0x80 max_size=1524 pak_size=1506 07 pak=0x600E3D8 ds=0x600E52A status=0x80 max_size=1524 pak_size=1506 08 pak=0x6020990 ds=0x6020AE2 status=0x80 max_size=1524 pak_size=386 09 pak=0x602D4E8 ds=0x602D63A status=0x80 max_size=1524 pak_size=98 10 pak=0x603A7C8 ds=0x603A91A status=0x80 max_size=1524 pak_size=98 11 pak=0x601D4D8 ds=0x601D62A status=0x80 max_size=1524 pak_size=98 12 pak=0x603BE60 ds=0x603BFB2 status=0x80 max_size=1524 pak_size=98 13 pak=0x60318B0 ds=0x6031A02 status=0x80 max_size=1524 pak_size=98 14 pak=0x601CD50 ds=0x601CEA2 status=0x80 max_size=1524 pak_size=98 15 pak=0x602C5D8 ds=0x602C72A status=0x80 max_size=1524 pak_size=98 16 pak=0x60245D0 ds=0x6024722 status=0x80 max_size=1524 pak_size=98 17 pak=0x6008328 ds=0x600847A status=0x80 max_size=1524 pak_size=98 18 pak=0x601EB70 ds=0x601ECC2 status=0x80 max_size=1524 pak_size=98 19 pak=0x602DC70 ds=0x602DDC2 status=0x80 max_size=1524 pak_size=98 20 pak=0x60163E0 ds=0x6016532 status=0x80 max_size=1524 pak_size=98 21 pak=0x602CD60 ds=0x602CEB2 status=0x80 max_size=1524 pak_size=98 22 pak=0x6037A98 ds=0x6037BEA status=0x80 max_size=1524 pak_size=98 23 pak=0x602BE50 ds=0x602BFA2 status=0x80 max_size=1524 pak_size=98 24 pak=0x6018988 ds=0x6018ADA status=0x80 max_size=1524 pak_size=98 25 pak=0x6033E58 ds=0x6033FAA status=0x80 max_size=1524 pak_size=98 26 pak=0x601BE40 ds=0x601BF92 status=0x80 max_size=1524 pak_size=98 27 pak=0x6026B78 ds=0x6026CCA status=0x80 max_size=1524 pak_size=98 28 pak=0x6024D58 ds=0x6024EAA status=0x80 max_size=1524 pak_size=74 29 pak=0x602AF40 ds=0x602B092 status=0x80 max_size=1524 pak_size=98 30 pak=0x601FA80 ds=0x601FBD2 status=0x80 max_size=1524 pak_size=98 31 pak=0x6038220 ds=0x6038372 status=0x80 max_size=1524 pak_size=98 TX ring with 8 entries at 0xDA20, tx_count = 0 tx_head = 0x600DA58 (12582919), head_txp = 0x5DC4 (7) tx_tail = 0x600DA58 (12582919), tail_txp = 0x5DC4 (7) 00 pak=0x000000 ds=0x600CF12 status=0x03 status2=0x0000 pak_size=118 01 pak=0x000000 ds=0x602126A status=0x03 status2=0x0000 pak_size=60 02 pak=0x000000 ds=0x600CF12 status=0x03 status2=0x0000 pak_size=118 03 pak=0x000000 ds=0x600CF12 status=0x03 status2=0x0000 pak_size=118 04 pak=0x000000 ds=0x600CF12 status=0x03 status2=0x0000 pak_size=118 05 pak=0x000000 ds=0x600CF12 status=0x03 status2=0x0000 pak_size=118 06 pak=0x000000 ds=0x600CF12 status=0x03 status2=0x0000 pak_size=118 07 pak=0x000000 ds=0x6003ED2 status=0x03 status2=0x0000 pak_size=126 0 missed datagrams, 0 overruns, 2 late collisions, 2 lost carrier events 0 transmitter underruns, 0 excessive collisions, 0 tdr, 0 babbles 0 memory errors, 0 spurious initialization done interrupts 0 no enp status, 0 buffer errors, 0 overflow errors 10 one_col, 10 more_col, 22 deferred, 0 tx_buff 0 throttled, 0 enabled Lance csr0 = 0x73

show controllers mci

Use the show controllers mci privileged EXEC command to display all information about the Multiport Communications Interface card. This command displays information the system uses for bridging and routing that is specific to the interface hardware. The information displayed is generally useful for diagnostic tasks performed by technical support personnel only.

show controllers mci
Syntax Description

This command has no arguments or keywords.

Command Mode

Privileged EXEC

Sample Display

The following is sample output from the show controllers mci command:

cs# show controllers mci MCI 0, controller type 1.1, microcode version 1.8     128 Kbytes of main memory, 4 Kbytes cache memory 22 system TX buffers, largest buffer size 1520     Restarts: 0 line down, 0 hung output, 0 controller error Interface 0 is Ethernet0, station address 0000.0c00.d4a6     15 total RX buffers, 11 buffer TX queue limit, buffer size 1520     Transmitter delay is 0 microseconds Interface 1 is Serial0, electrical interface is V.35 DTE     15 total RX buffers, 11 buffer TX queue limit, buffer size 1520     Transmitter delay is 0 microseconds     High speed synchronous serial interface Interface 2 is Ethernet1, station address aa00.0400.3be4     15 total RX buffers, 11 buffer TX queue limit, buffer size 1520     Transmitter delay is 0 microseconds Interface 3 is Serial1, electrical interface is V.35 DCE     15 total RX buffers, 11 buffer TX queue limit, buffer size 1520     Transmitter delay is 0 microseconds     High speed synchronous serial interface

Table 6-8 describes significant fields shown in the display.


Show Controllers MCI Field Descriptions
Field Description
MCI 0 Card type and unit number (varies depending on card)
controller type 1.1 Version number of the card
microcode version 1.8 Version number of the card's internal software (in read-only memory)
128 Kbytes of main memory Amount of main memory on the card
4 Kbytes cache memory Amount of cache memory on the card
22 system TX buffers Number of buffers that hold packets to be transmitted
largest buffer size 1520 Largest size of these buffers (in bytes)
Restarts
   0 line down
   0 hung output
   0 controller error
Count of restarts due to the following conditions:
   Communication line down
   Output unable to transmit
   Internal error
Interface 0 is Ethernet0 Names of interfaces, by number
electrical interface is V.35 DTE Line interface type for serial connections
15 total RX buffers Number of buffers for received packets
11 buffer TX queue limit Maximum number of buffers in transmit queue
Transmitter delay is 0 microseconds Delay between outgoing frames
Station address 0000.0c00.d4a6 Hardware address of the interface

Note The interface type is only queried at startup. If the hardware changes subsequent to initial startup, then the wrong type is reported. This has no adverse effect on the operation of the software. For instance, if a DCE cable is connected to a dual-mode V.35 applique after the unit has been booted, then the display presented for show interfaces incorrectly reports attachment to a DTE device although the software recognizes the DCE interface and behaves accordingly.
Related Command

tx-queue-limit

show controllers serial

Use the show controllers serial privileged EXEC command to display information that is specific to the interface hardware. The information displayed is generally useful for diagnostic tasks performed by technical support personnel only.

show controllers serial
Syntax Description

This command has no arguments or keywords.

Command Mode

Privileged EXEC

Sample Display

Sample output of the show controllers serial command:

cs# show controllers serial MK5 unit 0, NIM slot 1, NIM type code 7, NIM version 1 idb = 0x6150, driver structure at 0x34A878, regaddr = 0x8100300 IB at 0x6045500: mode=0x0108, local_addr=0, remote_addr=0 N1=1524, N2=1, scaler=100, T1=1000, T3=2000, TP=1 buffer size 1524 DTE V.35 serial cable attached RX ring with 32 entries at 0x45560 : RLEN=5, Rxhead 0 00 pak=0x6044D78 ds=0x6044ED4 status=80 max_size=1524 pak_size=0 01 pak=0x60445F0 ds=0x604474C status=80 max_size=1524 pak_size=0 02 pak=0x6043E68 ds=0x6043FC4 status=80 max_size=1524 pak_size=0 03 pak=0x60436E0 ds=0x604383C status=80 max_size=1524 pak_size=0 04 pak=0x6042F58 ds=0x60430B4 status=80 max_size=1524 pak_size=0 05 pak=0x60427D0 ds=0x604292C status=80 max_size=1524 pak_size=0 06 pak=0x6042048 ds=0x60421A4 status=80 max_size=1524 pak_size=0 07 pak=0x60418C0 ds=0x6041A1C status=80 max_size=1524 pak_size=0 08 pak=0x6041138 ds=0x6041294 status=80 max_size=1524 pak_size=0 09 pak=0x60409B0 ds=0x6040B0C status=80 max_size=1524 pak_size=0 10 pak=0x6040228 ds=0x6040384 status=80 max_size=1524 pak_size=0 11 pak=0x603FAA0 ds=0x603FBFC status=80 max_size=1524 pak_size=0 12 pak=0x603F318 ds=0x603F474 status=80 max_size=1524 pak_size=0 13 pak=0x603EB90 ds=0x603ECEC status=80 max_size=1524 pak_size=0 14 pak=0x603E408 ds=0x603E564 status=80 max_size=1524 pak_size=0 15 pak=0x603DC80 ds=0x603DDDC status=80 max_size=1524 pak_size=0 16 pak=0x603D4F8 ds=0x603D654 status=80 max_size=1524 pak_size=0 17 pak=0x603CD70 ds=0x603CECC status=80 max_size=1524 pak_size=0 18 pak=0x603C5E8 ds=0x603C744 status=80 max_size=1524 pak_size=0 19 pak=0x603BE60 ds=0x603BFBC status=80 max_size=1524 pak_size=0 20 pak=0x603B6D8 ds=0x603B834 status=80 max_size=1524 pak_size=0 21 pak=0x603AF50 ds=0x603B0AC status=80 max_size=1524 pak_size=0 22 pak=0x603A7C8 ds=0x603A924 status=80 max_size=1524 pak_size=0 23 pak=0x603A040 ds=0x603A19C status=80 max_size=1524 pak_size=0 24 pak=0x60398B8 ds=0x6039A14 status=80 max_size=1524 pak_size=0 25 pak=0x6039130 ds=0x603928C status=80 max_size=1524 pak_size=0 26 pak=0x60389A8 ds=0x6038B04 status=80 max_size=1524 pak_size=0 27 pak=0x6038220 ds=0x603837C status=80 max_size=1524 pak_size=0 28 pak=0x6037A98 ds=0x6037BF4 status=80 max_size=1524 pak_size=0 29 pak=0x6037310 ds=0x603746C status=80 max_size=1524 pak_size=0 30 pak=0x6036B88 ds=0x6036CE4 status=80 max_size=1524 pak_size=0 31 pak=0x6036400 ds=0x603655C status=80 max_size=1524 pak_size=0 TX ring with 8 entries at 0x45790 : TLEN=3, TWD=7 tx_count = 0, tx_head = 7, tx_tail = 7 00 pak=0x000000 ds=0x600D70C status=0x38 max_size=1524 pak_size=22 01 pak=0x000000 ds=0x600D70E status=0x38 max_size=1524 pak_size=2 02 pak=0x000000 ds=0x600D70E status=0x38 max_size=1524 pak_size=2 03 pak=0x000000 ds=0x600D70E status=0x38 max_size=1524 pak_size=2 04 pak=0x000000 ds=0x600D70E status=0x38 max_size=1524 pak_size=2 05 pak=0x000000 ds=0x600D70E status=0x38 max_size=1524 pak_size=2 06 pak=0x000000 ds=0x600D70E status=0x38 max_size=1524 pak_size=2 07 pak=0x000000 ds=0x6000000 status=0x38 max_size=1524 pak_size=0 XID/Test TX desc at 0xFFFFFF, status=0x30, max_buffer_size=0, packet_size=0 XID/Test RX desc at 0xFFFFFF, status=0x0, max_buffer_size=0, packet_size=0 Status Buffer at 0x60459C8: rcv=0, tcv=0, local_state=0, remote_state=0 phase=0, tac=0, currd=0x00000, curxd=0x00000 bad_frames=0, frmrs=0, T1_timeouts=0, rej_rxs=0, runts=0 0 missed datagrams, 0 overruns, 0 bad frame addresses 0 bad datagram encapsulations, 0 user primitive errors 0 provider primitives lost, 0 unexpected provider primitives 0 spurious primitive interrupts, 0 memory errors, 0 tr %LINEPROTO-5-UPDOWN: Linansmitter underruns mk5025 registers: csr0 = 0x0E00, csr1 = 0x0302, csr2 = 0x0704 csr3 = 0x5500, csr4 = 0x0214, csr5 = 0x0008

show controllers token

To display information about memory management, error counters, and the CSC-1R, CSC-2R, and or CSC-R16M Token Ring interface cards, use the show controllers token privileged EXEC command.

show controllers token
Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Usage Guidelines

Depending on the board being used, the output can vary. This command also displays information that is proprietary to Cisco Systems. Thus, the information that show controllers token displays is of primary use to Cisco technical personnel. Information that is useful to users can be obtained using the show interfaces tokenring command, described later in this chapter.

Sample Display

The following is sample output of the show controllers token command:

cs# show controllers token TR Unit 0 is board 0 - ring 0 state 3, dev blk: 0x1D2EBC, mailbox: 0x2100010, sca: 0x2010000 current address: 0000.3080.6f40, burned in address: 0000.3080.6f40 current TX ptr: 0xBA8, current RX ptr: 0x800 Last Ring Status: none Stats: soft:0/0, hard:0/0, sig loss:0/0 tx beacon: 0/0, wire fault 0/0, recovery: 0/0 only station: 0/0, remote removal: 0/0 Bridge: local 3330, bnum 1, target 3583 max_hops 7, target idb: 0x0, not local Interface failures: 0 -- Bkgnd Ints: 0 TX shorts 0, TX giants 0 Monitor state: (active) flags 0xC0, state 0x0, test 0x0, code 0x0, reason 0x0 f/w ver: 1.0, chip f/w: '000000.ME31100', [bridge capable] SMT versions: 1.01 kernel, 4.02 fastmac ring mode: F00, internal enables: SRB REM RPS CRS/NetMgr internal functional: 0000011A (0000011A), group: 00000000 (00000000) if_state: 1, ints: 0/0, ghosts: 0/0, bad_states: 0/0 t2m fifo purges: 0/0 t2m fifo current: 0, t2m fifo max: 0/0, proto_errs: 0/0 ring: 3330, bridge num: 1, target: 3583, max hops: 7 Packet counts: receive total: 298/6197, small: 298/6197, large 0/0 runts: 0/0, giants: 0/0 local: 298/6197, bridged: 0/0, promis: 0/0 bad rif: 0/0, multiframe: 0/0 ring num mismatch 0/0, spanning violations 0 transmit total: 1/25, small: 1/25, large 0/0 runts: 0/0, giants: 0/0, errors 0/0 bad fs: 0/0, bad ac: 0 congested: 0/0, not present: 0/0 Unexpected interrupts: 0/0, last unexp. int: 0 Internal controller counts:     line errors: 0/0, internal errors: 0/0     burst errors: 0/0, ari/fci errors: 0/0     abort errors: 0/0, lost frame: 0/0     copy errors: 0/0, rcvr congestion: 0/0     token errors: 0/0, frequency errors: 0/0     dma bus errors: -/-, dma parity errors: -/- Internal controller smt state:     Adapter MAC: 0000.3080.6f40, Physical drop: 00000000     NAUN Address: 0000.a6e0.11a6, NAUN drop: 00000000     Last source: 0000.a6e0.11a6, Last poll: 0000.3080.6f40     Last MVID: 0006, Last attn code: 0006     Txmit priority: 0006, Auth Class: 7FFF     Monitor Error: 0000, Interface Errors: FFFF     Correlator: 0000, Soft Error Timer: 00C8     Local Ring: 0000, Ring Status: 0000     Beacon rcv type: 0000, Beacon txmit type: 0000     Beacon type: 0000, Beacon NAUN: 0000.a6e0.11a6

Table 6-9 describes the fields shown in the following line of sample output.

TR Unit 0 is board 0 - ring 0


Show Controllers Token Field Descriptions--Part 1
Field Description
TR Unit 0 Unit number assigned to the Token Ring interface associated with this output
is board 0 Board number assigned to the Token Ring controller board associated with this interface
ring 0 Number of the Token Ring associated with this board

In the following output line, state 3 indicates the state of the board. The rest of this output line displays memory mapping that is of primary use to Cisco engineers.

state 3, dev blk: 0x1D2EBC, mailbox: 0x2100010, sca: 0x2010000

The following line also appears in show interface token output as the address and burned-in address, respectively:

current address: 0000.3080.6f40, burned in address: 0000.3080.6f40

The following line of output displays buffer management pointers that change by board:

current TX ptr: 0xBA8, current RX ptr: 0x800

The following line of output indicates the ring status from the controller chip set. This information is used by LAN Network Manager:

Last Ring Status: none

The following lines of output show Token Ring statistics. See the Token Ring specification for more information.

Stats: soft:0/0, hard:0/0, sig loss:0/0 tx beacon: 0/0, wire fault 0/0, recovery: 0/0 only station: 0/0, remote removal: 0/0

The following line of output indicates that Token Ring communication has been enabled on the interface. If this line of output appears, the message "Source Route Bridge capable" should appear in the show interfaces tokenring display.

Bridge: local 3330, bnum 1, target 3583

Table 6-10 describes the fields shown in the following line of sample output.

max_hops 7, target idb: 0x0, not local
Show Controllers Token Field Descriptions--Part 2
Field Description
max_hops 7 Maximum number of bridges.
target idb: 0x0 Destination interface definition.
not local Indicates whether the interface has been defined as a local or remote bridge.

The following line of output is specific to the hardware:

Interface failures: 0 -- Bkgnd Ints: 0

In the following line of output, TX shorts are the number of packets the interface transmits that are discarded because they are smaller than the medium's minimum packet size. TX giants are the number of packets the interface transmits that are discarded because they exceed the medium's maximum packet size.

TX shorts 0, TX giants 0

The following line of output indicates the state of the controller. Possible values include active, failure, inactive, and reset:

Monitor state: (active)

The following line of output displays detailed information relating to the monitor state shown in the previous line of output. This information relates to the firmware on the controller. This information is relevant to Cisco engineers only if the monitor state is something other than active.

flags 0xC0, state 0x0, test 0x0, code 0x0, reason 0x0

Table 6-11 describes the fields in the following line of output:

f/w ver: 1.0 expr 0, chip f/w: '000000.ME31100', [bridge capable]
Show Controllers Token Field Descriptions--Part 3
Field Description
f/w ver: 1.0 Version of the Cisco firmware on the board.
chip f/w: '000000.ME31100' Firmware on the chip set.
[bridge capable] Interface has not been configured for bridging, but that it has that capability.

The following line of output displays the version numbers for the kernel and the accelerator microcode of the Madge firmware on the board; this firmware is the LLC interface to the chip set:

SMT versions: 1.01 kernel, 4.02 fastmac

The following line of output displays LAN Network Manager information that relates to ring status:

ring mode: F00, internal enables: SRB REM RPS CRS/NetMgr

The following line of output corresponds to the functional address and the group address shown in show interfaces tokenring output:

internal functional: 0000011A (0000011A), group: 00000000 (00000000)

The following line of output displays interface board state information that is proprietary to Cisco Systems:

if_state: 1, ints: 0/0, ghosts: 0/0, bad_states: 0/0

The following output lines display information that is proprietary to Cisco Systems. Cisco engineers use this information for debugging purposes.

t2m fifo purges: 0/0 t2m fifo current: 0, t2m fifo max: 0/0, proto_errs: 0/0

Each of the fields in the following line of output maps to a field in the show source bridge display, as follows: ring maps to srn; bridge num maps to bn; target maps to trn; and max hops maps to max:

ring: 3330, bridge num: 1, target: 3583, max hops: 7

In the following lines of output, the number preceding the slash (/) indicates the count since the value was last displayed; the number following the slash (/) indicates count since the system was last booted:

Packet counts: receive total: 298/6197, small: 298/6197, large 0/0

In the following line of output, the number preceding the slash (/) indicates the count since the value was last displayed; the number following the slash (/) indicates count since the system was last booted. The runts and giants values that appear here correspond to the runts and giants values that appear in show interfaces tokenring output.

runts: 0/0, giants: 0/0

The following lines of output are receiver-specific information that Cisco engineers can use for debugging purposes:

local: 298/6197, bridged: 0/0, promis: 0/0 bad rif: 0/0, multiframe: 0/0 ring num mismatch 0/0, spanning violations 0 transmit total: 1/25, small: 1/25, large 0/0 runts: 0/0, giants: 0/0, errors 0/0

The following output lines include very specific statistics that are not relevant in most cases, but exist for historical purposes. In particular, the internal errors, burst errors, ari/fci, abort errors, copy errors, frequency errors, dma bus errors, and dma parity errors fields are not relevant.

Internal controller counts: line errors: 0/0, internal errors: 0/0 burst errors: 0/0, ari/fci errors: 0/0 abort errors: 0/0, lost frame: 0/0 copy errors: 0/0, rcvr congestion: 0/0 token errors: 0/0, frequency errors: 0/0 dma bus errors: -/-, dma parity errors: -/-

The following lines of output are low-level Token Ring interface statistics relating to the state and status of the Token Ring with respect to all other Token Rings on the line:

Internal controller smt state: Adapter MAC: 0000.3080.6f40, Physical drop: 00000000 NAUN Address: 0000.a6e0.11a6, NAUN drop: 00000000 Last source: 0000.a6e0.11a6, Last poll: 0000.3080.6f40 Last MVID: 0006, Last attn code: 0006 Txmit priority: 0006, Auth Class: 7FFF Monitor Error: 0000, Interface Errors: FFFF Correlator: 0000, Soft Error Timer: 00C8 Local Ring: 0000, Ring Status: 0000 Beacon rcv type: 0000, Beacon txmit type: 0000

show interfaces

Use the show interfaces EXEC command to display statistics for all interfaces configured on the communication server. The resulting output varies, depending on the network for which an interface has been configured.

show interfaces [type number] [accounting]
Syntax Description
type unit (Optional) Interface type. Allowed values include async, ethernet, loopback, null, serial, tokenring, and tunnel.
number (Optional) Interface number
accounting (Optional) Displays the number of packets of each protocol type that has been sent through the interface. You can show these numbers for all interfaces, or you can specify a specific type and number.
Command Mode

EXEC

Usage Guidelines

The show interfaces command displays statistics for the network interfaces. If you enter a show interfaces command for an interface type that has been removed from the communication server, interface statistics will be displayed accompanied by the following text: "Hardware has been removed."

You will use the show interfaces command frequently while configuring and monitoring communication servers. The various forms of the show interfaces commands are described in detail in the sections immediately following this command.

To display the number of packets of each protocol type that have been sent through all configured interfaces, use the show interfaces accounting EXEC command. When you use the accounting option, only the accounting statistics are displayed.

Table 6-12 lists the protocols for which per-packet accounting information is kept.


Per-Packet Counted Protocols
Protocol Notes
ARP For IP, Frame Relay, SMDS.
DEC MOP The communication servers use MOP packets to advertise their existence to DEC machines that use the MOP protocol. A communication server periodically broadcasts MOP packets to identify itself as a MOP host. This results in MOP packets being counted.
HP Probe --
IP --
Lan Manager LAN Network Manager and IBM Network Manager.
IPX --
Sample Display

The following is sample output from the show interfaces command. Because your display will depend on the type and number of interface cards in your communication server, only a portion of the display is shown.

cs# show interfaces Ethernet 0 is up, line protocol is up Hardware is MCI Ethernet, address is 0000.0c00.750c (bia 0000.0c00.750c) Internet address is 131.108.28.8, subnet mask is 255.255.255.0 MTU 1500 bytes, BW 10000 Kbit, DLY 100000 usec, rely 255/255, load 1/255 Encapsulation ARPA, loopback not set, keepalive set (10 sec) ARP type: ARPA, ARP Timeout 4:00:00 Last input 0:00:00, output 0:00:00, output hang never Last clearing of "show interface" counters 0:00:00 Output queue 0/40, 0 drops; input queue 0/75, 0 drops Five minute input rate 0 bits/sec, 0 packets/sec Five minute output rate 2000 bits/sec, 4 packets/sec 1127576 packets input, 447251251 bytes, 0 no buffer Received 354125 broadcasts, 0 runts, 0 giants 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 5332142 packets output, 496316039 bytes, 0 underruns 0 output errors, 432 collisions, 0 interface resets, 0 restarts ---More---
Sample Display with Accounting Option

The following is sample output from the show interfaces accounting command:

cs# show interfaces accounting Ethernet0 Protocol Pkts In Chars In Pkts Out Chars Out IP 873171 735923409 34624 9644258 Novell 163849 12361626 57143 4272468 DEC MOP 0 0 1 77 ARP 69618 4177080 1529 91740

When the output indicates an interface is "disabled," the communication server has received excessive errors (over 5000 in a keepalive period).

show interfaces async

Use the show interfaces async EXEC command to display information about the serial interface.

show interfaces async [unit] [accounting]
Syntax Description
unit (Optional) Must be 1.
accounting (Optional) Displays the number of packets of each protocol type that have been sent through the interface.
Command Mode

EXEC

Sample Display

The following is sample output from the show interfaces async command:

cs# show interfaces async 1 Async 1 is up, line protocol is up     Hardware is Async Serial Internet address is 1.0.0.1, subnet mask is 255.0.0.0 MTU 1500 bytes, BW 9 Kbit, DLY 100000 usec, rely 255/255, load 56/255 Encapsulation SLIP, keepalive set (0 sec) Last input 0:00:03, output 0:00:03, output hang never Last clearing of "show interface" counters never Output queue 0/3, 2 drops; input queue 0/0, 0 drops Five minute input rate 0 bits/sec, 1 packets/sec Five minute output rate 2000 bits/sec, 1 packets/sec 273 packets input, 13925 bytes, 0 no buffer Received 0 broadcasts, 0 runts, 0 giants 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 221 packets output, 41376 bytes, 0 underruns 0 output errors, 0 collisions, 0 interface resets, 0 restarts 0 carrier transitions
Note The communication server does not detect the start of a SLIP packet on an asynchronous interface. When the SLIP connection is established, the communication server only knows that it is working with the SLIP host that is generating traffic after it receives an END byte. Data that is transmitted before the END byte is counted as an error.

The following is a sample display from the show interfaces async accounting command:

cs# show interfaces async 0 accounting Async 0    Protocol   Pkts In    Chars In   Pkts Out    Chars Out     IP         7344       4787842    1803        1535774     DEC MOP 0   0        127     9779     ARP    7    420      39       2340

The show line and show slip commands can also be useful in monitoring asynchronous interfaces.

Table 6-13 describes the fields shown in the two sample displays.


Show Interfaces Async Field Descriptions
Field Description
Async... is {up | down |
administratively down}
Indicates whether the interface hardware is currently active (whether carrier detect is present) and if it has been taken down by an administrator.
line protocol is {up | down |
administratively down}
Indicates whether the software processes that handle the line protocol think the line is usable (that is, whether keepalives are successful).
Hardware is Hardware type.
Internet address is IP address.
Subnet mask is Subnet mask.
MTU Maximum transmission unit of the interface.
BW Bandwidth of the interface in kilobits per second.
DLY Delay of the interface in microseconds.
rely Reliability of the interface as a fraction of 255 (255/255 is 100% reliability), calculated as an exponential average over five minutes.
load Load on the interface as a fraction of 255 (255/255 is completely saturated), calculated as an exponential average over five minutes. The calculation uses the value from the bandwidth interface configuration command.
Encapsulation Encapsulation method assigned to interface.
keepalive Indicates whether keepalives are set or not.
Last input Number of hours, minutes, and seconds since the last packet was successfully received by an interface. Useful for knowing when a dead interface failed.
output The number of hours, minutes, and seconds since the last packet was successfully transmitted by an interface.
output hang Number of hours, minutes, and seconds (or never) since the interface was last reset because of a transmission that took too long. When the number of hours in any of the "last" fields exceeds 24 hours, the number of days and hours is printed. If that field overflows, asterisks are printed.
Last clearing The time at which the counters that measure cumulative statistics (such as number of bytes transmitted and received) shown in this report were last reset to zero. Note that variables that might affect routing (for example, load and reliability) are not cleared when the counters are cleared.
*** indicates the elapsed time is too large to be displayed.
0:00:00 indicates the counters were cleared more than 231ms (and less than 232ms) ago.
Output queue, drops
input queue, drops
Number of packets in output and input queues. Each number is followed by a slash, the maximum size of the queue, and the number of packets dropped due to a full queue.
Five minute input rate,
Five minute output rate
Average number of bits and packets transmitted per second in the last five minutes.
packets input Total number of error-free packets received by the system.
bytes Total number of bytes, including data and MAC encapsulation, in the error free packets received by the system.
no buffer Number of received packets discarded because there was no buffer space in the main system. Compare with ignored count. Broadcast storms on Ethernets and bursts of noise on serial lines are often responsible for no input buffer events.
broadcasts Total number of broadcast or multicast packets received by the interface.
runts Number of packets that are discarded because they are smaller than the medium's minimum packet size.
giants Number of packets that are discarded because they exceed the medium's maximum packet size.
input errors Total number of no buffer, runts, giants, CRCs, frame, overrun, ignored, and abort counts. Other input-related errors can also increment the count, so that this sum might not balance with the other counts.
CRC The cyclic redundancy checksum generated by the originating LAN station or far end device does not match the checksum calculated from the data received. On a LAN, this usually indicates noise or transmission problems on the LAN interface or the LAN bus itself. A high number of CRC's is usually the result of collisions or a station transmitting bad data. On a serial link, CRC's usually indicate noise, gain hits or other transmission problems on the data link.
frame Number of packets received incorrectly having a CRC error and a noninteger number of octets. On a serial line, this is usually the result of noise or other transmission problems.
overrun Number of times the serial receiver hardware was unable to hand received data to a hardware buffer because the input rate exceeded the receiver's ability to handle the data.
ignored Number of received packets ignored by the interface because the interface hardware ran low on internal buffers. These buffers are different than the system buffers mentioned previously in the buffer description. Broadcast storms and bursts of noise can cause the ignored count to be incremented.
abort Illegal sequence of one bits on a serial interface. This usually indicates a clocking problem between the serial interface and the data link equipment.
packets output Total number of messages transmitted by the system.
bytes Total number of bytes, including data and MAC encapsulation, transmitted by the system.
underruns Number of times that the far-end transmitter has been running faster than the near-end communication server's receiver can handle. This might never be reported on some interfaces.
output errors Sum of all errors that prevented the final transmission of datagrams out of the interface being examined. Note that this might not balance with the sum of the enumerated output errors, as some datagrams might have more than one error, and others might have errors that do not fall into any of the specifically tabulated categories.
interface resets Number of times an interface has been completely reset. This can happen if packets queued for transmission were not sent within several seconds. On a serial line, this can be caused by a malfunctioning modem that is not supplying the transmit clock signal, or by a cable problem. If the system notices that the carrier detect line of a serial interface is up, but the line protocol is down, it periodically resets the interface in an effort to restart it. Interface resets can also occur when an interface is looped back or shut down.
restarts Number of times the controller was restarted because of errors.
carrier transitions Number of times the carrier detect signal of a serial interface has changed state. Indicates modem or line problems if the carrier detect line is changing state often.
Protocol Protocol that is operating on the interface.
Pkts In Number of packets received for that protocol.
Chars In Number of characters received for that protocol.
Pkts Out Number of packets transmitted for that protocol.
Chars Out Number of characters transmitted for that protocol.

show interfaces dialer

Use the show interfaces dialer EXEC command to display information about the dialer interface.

show interfaces dialer unit [accounting]
Syntax Description
unit Must match a port number on the selected interface.
accounting (Optional) Displays the number of packets of each protocol type that have been sent through the interface.
Command Mode

EXEC

show interfaces ethernet

Use the show interfaces ethernet EXEC command to display information about an Ethernet interface on the communication server.

show interfaces ethernet unit [accounting]
Syntax Description
unit Must match a port number on the selected interface.
accounting (Optional) Displays the number of packets of each protocol type that have been sent through the interface.
Command Mode

EXEC

Usage Guidelines

If you do not provide values for the argument unit, the command will display statistics for all network interfaces. The optional keyword accounting displays the number of packets of each protocol type that have been sent through the interface.

Sample Display

The following is sample output from the show interfaces command for the Ethernet 0 interface:

cs# show interfaces ethernet 0 Ethernet 0 is up, line protocol is up     Hardware is MCI Ethernet, address is aa00.0400.0134 (bia 0000.0c00.4369)    Internet address is 131.108.1.1, subnet mask is 255.255.255.0    MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec, rely 255/255, load 1/255    Encapsulation ARPA, loopback not set, keepalive set (10 sec)     ARP type: ARPA, PROBE, ARP Timeout 4:00:00    Last input 0:00:00, output 0:00:00, output hang never    Output queue 0/40, 0 drops; input queue 0/75, 2 drops    Five minute input rate 61000 bits/sec, 4 packets/sec    Five minute output rate 1000 bits/sec, 2 packets/sec        2295197 packets input, 305539992 bytes, 0 no buffer        Received 1925500 broadcasts, 0 runts, 0 giants        3 input errors, 3 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort        3594664 packets output, 436549843 bytes, 0 underruns        8 output errors, 1790 collisions, 10 interface resets, 0 restarts

Table 6-14 describes significant fields shown in the display.


Show Interfaces Ethernet Field Descriptions
Field Description
Ethernet ... is up
...is administratively down
Indicates whether the interface hardware is currently active and if it has been taken down by an administrator. "Disabled" indicates the communication server has received over 5000 errors in a keepalive interval, which is 10 seconds by default.
line protocol is {up | down |
administratively down}
Indicates whether the software processes that handle the line protocol believe the interface is usable (that is, whether keepalives are successful) or if it has been taken down by an administrator.
Hardware Hardware type (for example, MCI Ethernet, SCI, Ethernet) and address.
Internet address IP address followed by subnet mask.
MTU Maximum transmission unit of the interface.
BW Bandwidth of the interface in kilobits per second.
DLY Delay of the interface in microseconds.
rely Reliability of the interface as a fraction of 255 (255/255 is 100% reliability), calculated as an exponential average over five minutes.
load Load on the interface as a fraction of 255 (255/255 is completely saturated), calculated as an exponential average over five minutes.
Encapsulation Encapsulation method assigned to interface.
loopback Indicates whether loopback is set or not.
keepalive Indicates whether keepalives are set or not.
ARP type: Type of Address Resolution Protocol assigned.
Last input Number of hours, minutes, and seconds since the last packet was successfully received by an interface. Useful for knowing when a dead interface failed.
output Number of hours, minutes, and seconds since the last packet was successfully transmitted by the interface. Useful for knowing when a dead interface failed.
output hang Number of hours, minutes, and seconds (or never) since the interface was last reset because of a transmission that took too long. When the number of hours in any of the "last" fields exceeds 24 hours, the number of days and hours is printed. If that field overflows, asterisks are printed.
Output queue, input queue, drops Number of packets in output and input queues. Each number is followed by a slash, the maximum size of the queue, and the number of packets dropped due to a full queue.
Five minute input rate,
Five minute output rate
Average number of bits and packets transmitted per second in the last five minutes. If the interface is not in promiscuous mode, it senses network traffic it sends and receives (rather than all network traffic).

The five-minute input and output rates should be used only as an approximation of traffic per second during a given five-minute period. These rates are exponentially weighted averages with a time constant of five minutes. A period of four time constants must pass before the average will be within two percent of the instantaneous rate of a uniform stream of traffic over that period.

packets input Total number of error-free packets received by the system.
bytes Total number of bytes, including data and MAC encapsulation, in the error free packets received by the system.
no buffer Number of received packets discarded because there was no buffer space in the main system. Compare with ignored count. Broadcast storms on Ethernets and bursts of noise on serial lines are often responsible for no input buffer events.
Received ... broadcasts Total number of broadcast or multicast packets received by the interface.
runts Number of packets that are discarded because they are smaller than the medium's minimum packet size. For instance, any Ethernet packet that is less than 64 bytes is considered a runt.
giants Number of packets that are discarded because they exceed the medium's maximum packet size. For example, any Ethernet packet that is greater than 1,518 bytes is considered a giant.
input errors Includes runts, giants, no buffer, CRC, frame, overrun, and ignored counts. Other input-related errors can also cause the input errors count to be increased, and some datagrams might have more than one error; therefore, this sum might not balance with the sum of enumerated input error counts.
CRC Cyclic redundancy check generated by the originating LAN station or far-end device does not match the checksum calculated from the data received. On a LAN, this usually indicates noise or transmission problems on the LAN interface or the LAN bus itself. A high number of CRCs is usually the result of collisions or a station transmitting bad data.
frame Number of packets received incorrectly having a CRC error and a noninteger number of octets. On a LAN, this is usually the result of collisions or a malfunctioning Ethernet device.
overrun Number of times the receiver hardware was unable to hand received data to a hardware buffer because the input rate exceeded the receiver's ability to handle the data.
ignored Number of received packets ignored by the interface because the interface hardware ran low on internal buffers. These buffers are different than the system buffers mentioned previously in the buffer description. Broadcast storms and bursts of noise can cause the ignored count to be increased.
abort Number of packets whose receipt was aborted.
packets output Total number of messages transmitted by the system.
bytes Total number of bytes, including data and MAC encapsulation, transmitted by the system.
underruns Number of times that the transmitter has been running faster than the communication server can handle. This might never be reported on some interfaces.
output errors Sum of all errors that prevented the final transmission of datagrams out of the interface being examined. Note that this might not balance with the sum of the enumerated output errors, as some datagrams might have more than one error, and others might have errors that do not fall into any of the specifically tabulated categories.
collisions Number of messages retransmitted due to an Ethernet collision. This is usually the result of an overextended LAN (Ethernet or transceiver cable too long, more than two repeaters between stations, or too many cascaded multiport transceivers). A packet that collides is counted only once in output packets.
interface resets Number of times an interface has been completely reset. This can happen if packets queued for transmission were not sent within several seconds' time. On a serial line, this can be caused by a malfunctioning modem that is not supplying the transmit clock signal, or by a cable problem. If the system notices that the carrier detect line of a serial interface is up, but the line protocol is down, it periodically resets the interface in an effort to restart it. Interface resets can also occur when an interface is looped back or shut down.
restarts Number of times a Type 2 Ethernet controller was restarted because of errors.

show interfaces loopback

Use the show interfaces loopback EXEC command to display information about the dialer interface.

show interfaces loopback [unit] [accounting]
Syntax Description
unit (Optional) Must match a port number on the selected interface.
accounting (Optional) Displays the number of packets of each protocol type that have been sent through the interface.
Command Mode

EXEC

Sample Displays

The following is sample output from the show interfaces loopback command:

cs# show interfaces loopback 0 Loopback0 is up, line protocol is up Hardware is Loopback MTU 1500 bytes, BW 1 Kbit, DLY 50 usec, rely 255/255, load 1/255 Encapsulation UNKNOWN, loopback not set, keepalive set (10 sec) Last input never, output never, output hang never Last clearing of "show interface" counters never Output queue 0/0, 0 drops; input queue 0/75, 0 drops Five minute input rate 0 bits/sec, 0 packets/sec Five minute output rate 0 bits/sec, 0 packets/sec

                          0 packets input, 0 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 0 input packets with dribble condition detected 0 packets output, 0 bytes, 0 underruns 0 output errors, 0 collisions, 0 interface resets, 0 restarts

The following is sample when the accounting keyword is included:

cs# show interfaces loopback 0 accounting Loopback0 Protocol Pkts In Chars In Pkts Out Chars Out No traffic sent or received on this interface.

Table 6-15 describes significant fields shown in the displays.


Show Interfaces Loopback Descriptions
Field Description
Loopback is {up | down |
administratively down
Indicates whether the interface hardware is currently active (whether carrier detect is present) and if it has been taken down by an administrator. "Disabled" indicates the communication server has received over 5000 errors in a keepalive interval, which is 10 seconds by default.
line protocol is {up | down |
administratively down}
Indicates whether the software processes that handle the line protocol considers the line usable (that is, whether keepalives are successful).
Hardware Hardware is Loopback.
MTU Maximum transmission unit of the interface.
BW Bandwidth of the interface in kilobits per second.
DLY Delay of the interface in microseconds.
rely Reliability of the interface as a fraction of 255 (255/255 is 100% reliability), calculated as an exponential average over five minutes.
load Load on the interface as a fraction of 255 (255/255 is completely saturated), calculated as an exponential average over five minutes.
Encapsulation Encapsulation method assigned to interface.
loopback Indicates whether loopback is set and type of loopback test.
keepalive Indicates whether keepalives are set or not.
Last input Number of hours, minutes, and seconds since the last packet was successfully received by an interface. Useful for knowing when a dead interface failed.
output Number of hours, minutes, and seconds since the last packet was successfully transmitted by an interface.
output hang Number of hours, minutes, and seconds (or never) since the interface was last reset because of a transmission that took too long. When the number of hours in any of the "last" fields exceeds 24 hours, the number of days and hours is printed. If that field overflows, asterisks are printed.
Last clearing Time at which the counters that measure cumulative statistics (such as number of bytes transmitted and received) shown in this report were last reset to zero. Note that variables that might affect routing (for example, load and reliability) are not cleared when the counters are cleared.
*** indicates the elapsed time is too large to be displayed.
0:00:00 indicates the counters were cleared more than 231ms (and less than 232ms) ago.
Output queue, drops
Input queue, drops
Number of packets in output and input queues. Each number is followed by a slash, the maximum size of the queue, and the number of packets dropped due to a full queue.
Five minute input rate,
Five minute output rate
Average number of bits and packets transmitted per second in the last five minutes.
packets input Total number of error-free packets received by the system.
bytes Total number of bytes, including data and MAC encapsulation, in the error free packets received by the system.
no buffer Number of received packets discarded because there was no buffer space in the main system. Compare with ignored count. Broadcast storms on Ethernets and bursts of noise on serial lines are often responsible for no input buffer events.
broadcasts Total number of broadcast or multicast packets received by the interface.
runts Number of packets that are discarded because they are smaller than the medium's minimum packet size.
giants Number of packets that are discarded because they exceed the medium's maximum packet size.
input errors Sum of all errors that prevented the receipt of datagrams on the interface being examined. This might not balance with the sum of the enumerated output errors, because some datagrams might have more than one error and others might have errors that do not fall into any of the specifically tabulated categories.
CRC Cyclic redundancy check generated by the originating LAN station or far-end device does not match the checksum calculated from the data received. On a LAN, this usually indicates noise or transmission problems on the LAN interface or the LAN bus itself. A high number of CRCs is usually the result of collisions or a station transmitting bad data. On a serial link, CRCs usually indicate noise, gain hits, or other transmission problems on the data link. CRC errors are also reported when a far-end abort occurs, and when the idle flag pattern is corrupted. This makes it possible to get CRC errors even when there is no data traffic.
frame Number of packets received incorrectly having a CRC error and a noninteger number of octets. On a serial line, this is usually the result of noise or other transmission problems.
overrun Number of times the serial receiver hardware was unable to hand received data to a hardware buffer because the input rate exceeded the receiver's ability to handle the data.
ignored Number of received packets ignored by the interface because the interface hardware ran low on internal buffers. These buffers are different than the system buffers mentioned previously in the buffer description. Broadcast storms and bursts of noise can cause the ignored count to be increased.
abort Number of packets whose receipt was aborted.
packets output Total number of messages transmitted by the system.
bytes output Total number of bytes, including data and MAC encapsulation, transmitted by the system.
underruns Number of times that the far-end transmitter has been running faster than the near-end communication server's receiver can handle. This might never happen (be reported) on some interfaces.
output errors Sum of all errors that prevented the final transmission of datagrams out of the interface being examined. Note that this might not balance with the sum of the enumerated output errors, as some datagrams might have more than one error, and others might have errors that do not fall into any of the specifically tabulated categories.
interface resets Number of times an interface has been completely reset. This can happen if packets queued for transmission were not sent within several seconds time. On a serial line, this can be caused by a malfunctioning modem that is not supplying the transmit clock signal, or by a cable problem. If the system notices that the carrier detect line of a serial interface is up, but the line protocol is down, it periodically resets the interface in an effort to restart it. Interface resets can also occur when an interface is looped back or shut down.
restarts Number of times the controller was restarted because of errors.
Protocol Protocol that is operating on the interface.
Pkts In Number of packets received for that protocol.
Chars In Number of characters received for that protocol.
Pkts Out Number of packets transmitted for that protocol.
Chars Out Number of characters transmitted for that protocol.

show interfaces serial

Use the show interfaces serial privileged EXEC command to display information about a serial interface.

show interfaces serial number [accounting]
Syntax Description
number (Optional) Must match the interface port number.
accounting (Optional) Displays the number of packets of each protocol type that have been sent through the interface.
Command Mode

Privileged EXEC

Sample Display

The following is sample output from the show interfaces command for a synchronous serial interface:

cs# show interfaces serial Serial 0 is up, line protocol is up     Hardware is MCI Serial    Internet address is 150.136.190.203, subnet mask is 255.255.255.0    MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255    Last input 0:00:07, output 0:00:00, output hang never    Output queue 0/40, 0 drops; input queue 0/75, 0 drops    Five minute input rate 0 bits/sec, 0 packets/sec    Five minute output rate 0 bits/sec, 0 packets/sec        16263 packets input, 1347238 bytes, 0 no buffer        Received 13983 broadcasts, 0 runts, 0 giants        2 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 2 abort 1 carrier transitions 22146 packets output, 2383680 bytes, 0 underruns 0 output errors, 0 collisions, 2 interface resets, 0 restarts

Table 6-16 describes significant fields shown in the display.


Show Interfaces Serial Field Descriptions
Field Description
Serial ... is {up | down |
administratively down}
Indicates whether the interface hardware is currently active (whether carrier detect is present) and if it has been taken down by an administrator. "Disabled" indicates the communication server has received over 5000 errors in a keepalive interval, which is 10 seconds by default.
line protocol is {up | down} Indicates whether the software processes that handle the line protocol consider the line usable (that is, whether keepalives are successful) or if it has been taken down by an administrator.
Hardware is Specifies the hardware type.
Internet address is Specifies the IP address.
subnet mask Subnet mask.
MTU Maximum transmission unit of the interface.
BW Indicates the value of the bandwidth parameter that has been configured for the interface (in kilobits per second). The bandwidth parameter is used to compute IGRP metrics only. If the interface is attached to a serial line with a line speed that does not match the default (1536 or 1544 for T1 and 56 for a standard synchronous serial line), use the bandwidth command to specify the correct line speed for this serial line.
DLY Delay of the interface in microseconds.
rely Reliability of the interface as a fraction of 255 (255/255 is 100% reliability), calculated as an exponential average over five minutes.
load Load on the interface as a fraction of 255 (255/255 is completely saturated), calculated as an exponential average over five minutes.
Last input Number of hours, minutes, and seconds since the last packet was successfully received by an interface. Useful for knowing when a dead interface failed.
output Number of hours, minutes, and seconds since the last packet was successfully transmitted by an interface.
output hang Number of hours, minutes, and seconds (or never) since the interface was last reset because of a transmission that took too long. When the number of hours in any of the "last" fields exceeds 24 hours, the number of days and hours is printed. If that field overflows, asterisks are printed.
Output queue, drops
input queue, drops
Number of packets in output and input queues. Each number is followed by a slash, the maximum size of the queue, and the number of packets dropped due to a full queue.
Five minute input rate
Five minute output rate
Average number of bits and packets transmitted per second in the last five minutes.

The five-minute input and output rates should be used only as an approximation of traffic per second during a given five-minute period. These rates are exponentially weighted averages with a time constant of five minutes. A period of four time constants must pass before the average will be within two percent of the instantaneous rate of a uniform stream of traffic over that period.

packets input Total number of error-free packets received by the system.
bytes Total number of bytes, including data and MAC encapsulation, in the error free packets received by the system.
no buffer Number of received packets discarded because there was no buffer space in the main system. Compare with ignored count. Broadcast storms on Ethernets and bursts of noise on serial lines are often responsible for no input buffer events.
Received ... broadcasts Total number of broadcast or multicast packets received by the interface.
runts Number of packets that are discarded because they are smaller than the medium's minimum packet size.
giants Number of packets that are discarded because they exceed the medium's maximum packet size.
input errors Total number of no buffer, runts, giants, CRCs, frame, overrun, ignored, and abort counts. Other input-related errors can also increment the count, so that this sum might not balance with the other counts.
CRC Cyclic redundancy check generated by the originating station or far-end device does not match the checksum calculated from the data received. On a serial link, CRCs usually indicate noise, gain hits, or other transmission problems on the data link.
frame Number of packets received incorrectly having a CRC error and a noninteger number of octets. On a serial line, this is usually the result of noise or other transmission problems.
overrun Number of times the serial receiver hardware was unable to hand received data to a hardware buffer because the input rate exceeded the receiver's ability to handle the data.
ignored Number of received packets ignored by the interface because the interface hardware ran low on internal buffers. Broadcast storms and bursts of noise can cause the ignored count to be increased.
abort Illegal sequence of one bits on a serial interface. This usually indicates a clocking problem between the serial interface and the data link equipment.
carrier transitions Number of times the carrier detect signal of a serial interface has changed state. Indicates modem or line problems if the carrier detect line is changing state often.
packets output Total number of messages transmitted by the system.
bytes Total number of bytes, including data and MAC encapsulation, transmitted by the system.
underruns Number of times that the transmitter has been running faster than the communication server can handle. This may never be reported on some interfaces.
output errors Sum of all errors that prevented the final transmission of datagrams out of the interface being examined. Note that this might not balance with the sum of the enumerated output errors, as some datagrams might have more than one error, and others might have errors that do not fall into any of the specifically tabulated categories.
collisions Number of messages retransmitted due to an Ethernet collision. This usually is the result of an overextended LAN (Ethernet or transceiver cable too long, more than two repeaters between stations, or too many cascaded multiport transceivers). Some collisions are normal. However, if your collision rate climbs to around 4-5%, you should consider verifying that there is no faulty equipment on the segment and/or moving some existing stations to a new segment. A packet that collides is counted only once in output packets.
interface resets Number of times an interface has been completely reset. This can happen if packets queued for transmission were not sent within several seconds' time. On a serial line, this can be caused by a malfunctioning modem that is not supplying the transmit clock signal, or by a cable problem. If the system notices that the carrier detect line of a serial interface is up, but the line protocol is down, it periodically resets the interface in an effort to restart it. Interface resets can also occur when an interface is looped back or shut down.
restarts Number of times the controller was restarted because of errors.
Sample Display with Frame Relay Encapsulation

When using the Frame Relay encapsulation, use the show interfaces command to display information on the multicast DLCI, the DLCI of the interface, and the LMI DLCI used for the local management interface.

The multicast DLCI and the local DLCI can be set using the frame-relay multicast-dlci and the frame-relay local-dlci configuration commands, or provided through the local management interface. The status information is taken from the LMI, when active.

The following is a sample display from the show interfaces serial output when using Frame Relay encapsulation:

cs# show interfaces serial Serial 2 is up, line protocol is up     Hardware type is MCI Serial     Internet address is 131.108.122.1, subnet mask is 255.255.255.0    MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255    Encapsulation FRAME-RELAY, loopback not set, keepalive set (10 sec)    multicast DLCI 1022, status defined, active    source DLCI 20, status defined, active    LMI DLCI 1023, LMI sent 10, LMI stat recvd 10, LMI upd recvd 2    Last input 7:21:29, output 0:00:37, output hang never    Output queue 0/100, 0 drops; input queue 0/75, 0 drops    Five minute input rate 0 bits/sec, 0 packets/sec    Five minute output rate 0 bits/sec, 0 packets/sec        47 packets input, 2656 bytes, 0 no buffer        Received 5 broadcasts, 0 runts, 0 giants        5 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 57 abort        518 packets output, 391205 bytes         0 output errors, 0 collisions, 0 interface resets, 0 restarts        1 carrier transitions

In this display, the multicast DLCI has been changed to 1022 with the frame-relay multicast-dlci interface configuration command.

The display shows the statistics for the LMI are the number of status inquiry messages sent (LMI sent), the number of status messages received (LMI recvd), and the number of status updates received (upd recvd). See the Frame Relay Interface specification for additional explanations of this output.

Sample Display with ANSI LMI

For a serial interface with the ANSI LMI enabled, use the show interfaces command to determine the LMI type implemented.

The following is a sample display from the show interfaces output for a serial interface with the ANSI LMI enabled.

cs# show interfaces serial Serial 1 is up, line protocol is up     Hardware is MCI Serial    Internet address is 131.108.121.1, subnet mask is 255.255.255.0    MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255    Encapsulation FRAME-RELAY, loopback not set, keepalive set    LMI DLCI 0, LMI sent 10, LMI stat recvd 10    LMI type is ANSI Annex D    Last input 0:00:00, output 0:00:00, output hang never    Output queue 0/40, 0 drops; input queue 0/75, 0 drops    Five minute input rate 0 bits/sec, 1 packets/sec    Five minute output rate 1000 bits/sec, 1 packets/sec        261 packets input, 13212 bytes, 0 no buffer        Received 33 broadcasts, 0 runts, 0 giants        0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort        238 packets output, 14751 bytes, 0 underruns        0 output errors, 0 collisions, 0 interface resets, 0 restarts

Notice that the show interfaces output for a serial interface with ANSI LMI is very similar to that for encapsulation set to Frame Relay, as shown in the previous display. Table 6-17 describes the differences that exist.


Show Interfaces Field Description with ANSI LMI
Field Description
LMI DLCI 0 Identifies the DLCI used by the LMI for this interface. Default: 1023.
LMI sent 10 Number of LMI packets the communication server sent.
LMI type is ANSI Annex D Indicates that the interface is configured for the ANS-adopted Frame Relay specification T1.617 Annex D.
Sample Display with LAPB Encapsulation

Use the show interfaces command to display operation statistics for an interface using LAPB encapsulation.

The following is sample output from the show interfaces command for a serial interface using LAPB encapsulation:

cs# show interfaces LAPB state is DISCONNECT, T1 3000, N1 12000, N2 20, K7, TH 3000 Window is closed IFRAMEs 12/28 RNRs 0/1 REJs 13/1 SABMs 1/13 FRMRs 3/0 DISCs 0/11

Table 6-18 shows the fields relevant to all LAPB connections.


Show Interfaces Serial Fields and Descriptions When LAPB Is Enabled
Parameter Description
LAPB state is DISCONNECT State of the LAPB protocol.
T1 3000, N1 12000, ... Current parameter settings.
Window is closed Indicates that no more frames can be transmitted until some outstanding frames have been acknowledged.
IFRAMEs 12/28 RNRs 0/1 ... Count of the different types of frames in the form of sent/received.
Show Interfaces Serial with PPP

An interface configured for synchronous PPP encapsulation differs from the standard show interface serial output in the fourth and fifth lines displayed. An interface configured for PPP might include the following information:

Encapsulation PPP, loopback not set, keepalive set (10 sec) PPP: No valid link quality reports received.

The output line that reads "PPP: No valid link quality reports received" indicates that no reports have been received. If link quality monitoring is not negotiated, then that line will indicate the following:

PPP: LQM not negotiated.

If LQM has been negotiated, and if link quality reports have been received, it will display the following:

PPP: LQR transmit interval 10 sec, receive interval 10 sec local tx/remote rx: packets 50/50 bytes 147/147 success 16/16 remote tx/local rx: packets 49/50 bytes 753/790 success 16/16

This display contrasts the number of packets and bytes transmitted with the number received by the remote end, and the number of successful link quality reports received.

show interfaces tokenring

Use the show interfaces tokenring EXEC command to display information about the Token Ring interface and the state of source route bridging.

show interfaces tokenring unit [accounting]
Syntax Description
unit Must match the interface port line number.
accounting (Optional) Displays the number of packets of each protocol type that have been sent through the interface.
Command Mode

EXEC

Usage Guidelines

The optional keyword accounting displays the number of packets of each protocol type that have been sent through the interface.

Sample Display

The following is sample output from the show interfaces tokenring command.

cs# show interfaces tokenring TokenRing 0 is up, line protocol is up Hardware is 16/4 Token Ring, address is 5500.2000.dc27 (bia 0000.3000.072b)     Internet address is 150.136.230.203, subnet mask is 255.255.255.0    MTU 8136 bytes, BW 16000 Kbit, DLY 630 usec, rely 255/255, load 1/255     Encapsulation SNAP, loopback not set, keepalive set (10 sec)    ARP type: SNAP, ARP Timeout 4:00:00    Ring speed: 16 Mbps   Single ring node, Source Route Bridge capable    Group Address: 0x00000000, Functional Address: 0x60840000     Last input 0:00:01, output 0:00:01, output hang never     Output queue 0/40, 0 drops; input queue 0/75, 0 drops     Five minute input rate 0 bits/sec, 0 packets/sec     Five minute output rate 0 bits/sec, 0 packets/sec    16339 packets input, 1496515 bytes, 0 no buffer         Received 9895 broadcasts, 0 runts, 0 giants         0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 32648 packets output, 9738303 bytes, 0 underruns 0 output errors, 0 collisions, 2 interface resets, 0 restarts 5 transitions

Table 6-19 describes significant fields shown in the display.


Show Interfaces Tokenring Field Descriptions
Field Description
Token Ring is up | down Interface is either currently active and inserted into ring (up) or inactive and not inserted (down).

"Disabled" indicates the communication server has received over 5000 errors in a keepalive interval, which is 10 seconds by default.

Token Ring is Reset Hardware error has occurred.
Token Ring is Initializing Hardware is up, in the process of inserting the ring.
Token Ring is
Administratively Down
Hardware has been taken down by an administrator.
line protocol is {up | down |
administratively down}
Indicates whether the software processes that handle the line protocol believe the interface is usable (that is, whether keepalives are successful).
Hardware Hardware type. "Hardware is Token Ring" indicates that the board is a CSC-R board. "Hardware is 16/4 Token Ring" indicates that the board is a CSC-R16 board. Also shows the address of the interface.
Internet address Lists the IP address followed by subnet mask.
MTU Maximum transmission unit of the interface.
BW Bandwidth of the interface in kilobits per second.
DLY Delay of the interface in microseconds.
rely Reliability of the interface as a fraction of 255 (255/255 is 100% reliability), calculated as an exponential average over five minutes.
load Load on the interface as a fraction of 255 (255/255 is completely saturated), calculated as an exponential average over five minutes.
Encapsulation Encapsulation method assigned to interface.
loopback Indicates whether loopback is set or not.
keepalive Indicates whether keepalives are set or not.
ARP type Type of Address Resolution Protocol assigned.
Ring speed Speed of Token Ring--4 or 16 Mbps.
{Single ring/multiring node} Indicates whether a node is enabled to collect and use source routing information (RIF) for routable Token Ring protocols.
Group Address Interface's group address, if any. The group address is a multicast address; any number of interfaces on the ring can share the same group address. Each interface can have at most one group address.
Last input Number of hours, minutes, and seconds since the last packet was successfully received by an interface. Useful for knowing when a dead interface failed.
output Number of hours, minutes, and seconds since the last packet was successfully transmitted by an interface.
output hang Number of hours, minutes, and seconds (or never) since the interface was last reset because of a transmission that took too long. When the number of hours in any of the "last" fields exceeds 24 hours, the number of days and hours is printed. If that field overflows, asterisks are printed.
Output queue, drops
Input queue, drops
Number of packets in output and input queues. Each number is followed by a slash, the maximum size of the queue, and the number of packets dropped due to a full queue.
Five minute input rate,
Five minute output rate
Average number of bits and packets transmitted per second in the last five minutes.

The five-minute input and output rates should be used only as an approximation of traffic per second during a given five-minute period. These rates are exponentially weighted averages with a time constant of five minutes. A period of four time constants must pass before the average will be within two percent of the instantaneous rate of a uniform stream of traffic over that period.

packets input Total number of error-free packets received by the system.
bytes Total number of bytes, including data and MAC encapsulation, in the error free packets received by the system.
no buffer Number of received packets discarded because there was no buffer space in the main system. Compare with ignored count. Broadcast storms on Ethernets and bursts of noise on serial lines are often responsible for no input buffer events.
Received... broadcasts Total number of broadcast or multicast packets received by the interface.
runts Number of packets that are discarded because they are smaller than the medium's minimum packet size.
giants Number of packets that are discarded because they exceed the medium's maximum packet size.
input errors Total number of no buffer, runts, giants, CRCs, frame, overrun, ignored, and abort counts. Other input-related errors can also increment the count, so that this sum might not balance with the other counts.
CRC Cyclic redundancy check generated by the originating LAN station or far-end device does not match the checksum calculated from the data received. On a LAN, this usually indicates noise or transmission problems on the LAN interface or the LAN bus itself. A high number of CRCs is usually the result of a station transmitting bad data.
frame Number of packets received incorrectly having a CRC error and a noninteger number of octets.
overrun Number of times the serial receiver hardware was unable to hand received data to a hardware buffer because the input rate exceeded the receiver's ability to handle the data.
ignored Number of received packets ignored by the interface because the interface hardware ran low on internal buffers. These buffers are different than the system buffers mentioned previously in the buffer description. Broadcast storms and bursts of noise can cause the ignored count to be increased.
packets output Total number of messages transmitted by the system.
bytes Total number of bytes, including data and MAC encapsulation, transmitted by the system.
underruns Number of times that the far-end transmitter has been running faster than the near-end communication server's receiver can handle. This might never be reported on some interfaces.
output errors Sum of all errors that prevented the final transmission of datagrams out of the interface being examined. Note that this might not balance with the sum of the enumerated output errors, as some datagrams might have more than one error, and others might have errors that do not fall into any of the specifically tabulated categories.
collisions Since a Token Ring cannot have collisions, this statistic is nonzero only if an unusual event occurred when frames were being queued or dequeued by the system software.
interface resets Number of times an interface has been reset. The interface may be reset by the administrator or automatically when an internal error occurs.
restarts Should always be zero for Token Ring interfaces.
transitions Number of times the ring made a transition from up to down, or vice versa. A large number of transitions indicates a problem with the ring or the interface.

show interfaces tunnel

To list tunnel interface information, use the show interfaces tunnel EXEC command.

show interfaces tunnel unit [accounting]
Syntax Description
unit Must match the interface port line number.
accounting (Optional) Displays the number of packets of each protocol type that have been sent through the interface.
Command Mode

EXEC

Sample Display

The following example provides sample output from the show interface tunnel command:

cs# show interfaces tunnel 4 Tunnel4 is up, line protocol is down Hardware is Routing Tunnel MTU 1500 bytes, BW 9 Kbit, DLY 500000 usec, rely 255/255, load 1/255 Encapsulation TUNNEL, loopback not set, keepalive set (10 sec) Tunnel source 0.0.0.0, destination 0.0.0.0 Tunnel protocol/transport GRE/IP, key disabled, sequencing disabled Last input never, output never, output hang never Last clearing of "show interface" counters never Output queue 0/0, 0 drops; input queue 0/75, 0 drops Five minute input rate 0 bits/sec, 0 packets/sec Five minute output rate 0 bits/sec, 0 packets/sec 0 packets input, 0 bytes, 0 no buffer Received 0 broadcasts, 0 runts, 0 giants 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 0 input packets with dribble condition detected 0 packets output, 0 bytes, 0 underruns 0 output errors, 0 collisions, 0 interface resets, 0 restarts

Table 6-20 describes significant fields shown in the display.


Show Interfaces Tunnel Field Descriptions
Field Description
Tunnel is up | down Interface is currently active and inserted into ring (up) or inactive and not inserted (down).
line protocol is {up | down | administratively down} Shows line protocol up if a valid route is available to the tunnel destination. Shows line protocol down if no route is available, or if the route would be recursive.
Hardware Specifies the hardware type.
MTU Maximum transmission unit of the interface.
BW Bandwidth of the interface in kilobits per second.
DLY Delay of the interface in microseconds.
rely Reliability of the interface as a fraction of 255 (255/255 is 100% reliability), calculated as an exponential average over five minutes.
load Load on the interface as a fraction of 255 (255/255 is completely saturated), calculated as an exponential average over five minutes.
Encapsulation Encapsulation method is always TUNNEL for tunnels.
loopback Indicates whether loopback is set or not.
keepalive Indicates whether keepalives are set or not.
Tunnel source IP address used as the source address for packets in the tunnel.
destination IP address of the host destination.
Tunnel protocol Tunnel transport protocol (the protocol the tunnel is using). This is based on the tunnel mode command, which defaults to GRE.
key ID key for the tunnel interface, unless disabled.
sequencing Indicates whether the tunnel interface drops datagrams that arrive out of order. Can be disabled.
Last input Number of hours, minutes, and seconds since the last packet was successfully received by an interface. Useful for knowing when a dead interface failed.
output Number of hours, minutes, and seconds since the last packet was successfully transmitted by an interface.
output hang Number of hours, minutes, and seconds (or never) since the interface was last reset because of a transmission that took too long. When the number of hours in any of the "last" fields exceeds 24 hours, the number of days and hours is printed. If that field overflows, asterisks are printed.
Last clearing Time at which the counters that measure cumulative statistics (such as number of bytes transmitted and received) shown in this report were last reset to zero. Note that variables that might affect routing (for example, load and reliability) are not cleared when the counters are cleared.
*** indicates the elapsed time is too large to be displayed.
0:00:00 indicates the counters were cleared more than 231ms (and less than 232ms) ago.
Output queue, drops
Input queue, drops
Number of packets in output and input queues. Each number is followed by a slash, the maximum size of the queue, and the number of packets dropped due to a full queue.
Five minute input rate,
Five minute output rate
Average number of bits and packets transmitted per second in the last five minutes.

The five-minute input and output rates should be used only as an approximation of traffic per second during a given five-minute period. These rates are exponentially weighted averages with a time constant of five minutes. A period of four time constants must pass before the average will be within two percent of the instantaneous rate of a uniform stream of traffic over that period.

packets input Total number of error-free packets received by the system.
bytes Total number of bytes, including data and MAC encapsulation, in the error free packets received by the system.
no buffer Number of received packets discarded because there was no buffer space in the main system. Compare with ignored count. Broadcast storms on Ethernets and bursts of noise on serial lines are often responsible for no input buffer events.
Received... broadcasts Total number of broadcast or multicast packets received by the interface.
runts Number of packets that are discarded because they are smaller than the medium's minimum packet size.
giants Number of packets that are discarded because they exceed the medium's maximum packet size.
CRC Cyclic redundancy check generated by the originating LAN station or far-end device does not match the checksum calculated from the data received. On a LAN, this usually indicates noise or transmission problems on the LAN interface or the LAN bus itself. A high number of CRCs is usually the result of a station transmitting bad data.
frame Number of packets received incorrectly having a CRC error and a noninteger number of octets.
overrun Number of times the serial receiver hardware was unable to hand received data to a hardware buffer because the input rate exceeded the receiver's ability to handle the data.
ignored Number of received packets ignored by the interface because the interface hardware ran low on internal buffers. These buffers are different than the system buffers mentioned previously in the buffer description. Broadcast storms and bursts of noise can cause the ignored count to be increased.
abort Illegal sequence of one bits on a serial interface. This usually indicates a clocking problem between the serial interface and the data link equipment.
packets output Total number of messages transmitted by the system.
bytes Total number of bytes, including data and MAC encapsulation, transmitted by the system.
underruns Number of times that the far-end transmitter has been running faster than the near-end communication server's receiver can handle. This might never be reported on some interfaces.
output errors Sum of all errors that prevented the final transmission of datagrams out of the interface being examined. Note that this might not balance with the sum of the enumerated output errors, as some datagrams might have more than one error, and others might have errors that do not fall into any of the specifically tabulated categories.
collisions Number of messages retransmitted due to an Ethernet collision. This usually is the result of an overextended LAN (Ethernet or transceiver cable too long, more than two repeaters between stations, or too many cascaded multiport transceivers). Some collisions are normal. However, if your collision rate climbs to around 4-5%, you should consider verifying that there is no faulty equipment on the segment and/or moving some existing stations to a new segment. A packet that collides is counted only once in output packets.
interface resets Number of times an interface has been reset. The interface may be reset by the administrator or automatically when an internal error occurs.
restarts Number of times the controller was restarted because of errors.
Related Commands

A dagger (+) indicates that the command is documented in another chapter.

show ip route +
show route +

show ip interface

To list a summary of an interface's IP information and status, use the show ip interface privileged EXEC command.

show ip interface [brief] [type] [number]
Syntax Description
brief (Optional) Displays a brief summary of IP status and configuration.
type (Optional) Specifies that information be displayed about that interface type only. The possible value depends on the type of interfaces the system has. For example, it could be ethernet, null, serial, tokenring, and so on.
number (Optional) Interface number.
Command Mode

Privileged EXEC

Sample Displays

The following is sample output from the show ip interface command:

Router# show ip interface Ethernet0 is administratively down, line protocol is down Internet address is 1.0.46.10, subnet mask is 255.0.0.0 Broadcast address is 255.255.255.255 Address determined by setup command MTU is 1500 bytes Helper address is not set Directed broadcast forwarding is enabled Multicast groups joined: 224.0.0.1 224.0.0.2 Outgoing access list is not set Inbound access list is not set Proxy ARP is enabled Security level is default Split horizon is enabled ICMP redirects are always sent ICMP unreachables are always sent ICMP mask replies are never sent IP fast switching is enabled IP fast switching on the same interface is disabled IP SSE switching is disabled Router Discovery is disabled IP accounting is disabled TCP/IP header compression is disabled Probe proxy name replies are disabled Gateway Discovery is disabled PCbus0 is administratively down, line protocol is down Internet address is 198.135.1.43, subnet mask is 255.255.255.0 Broadcast address is 255.255.255.255 Address determined by setup command MTU is 1500 bytes Helper address is not set Directed broadcast forwarding is enabled Multicast groups joined: 224.0.0.1 224.0.0.2 Outgoing access list is not set Inbound access list is not set Proxy ARP is enabled Security level is default Split horizon is enabled ICMP redirects are always sent ICMP unreachables are always sent ICMP mask replies are never sent IP fast switching is enabled IP fast switching on the same interface is disabled IP SSE switching is disabled Router Discovery is disabled IP accounting is disabled TCP/IP header compression is disabled Probe proxy name replies are disabled Gateway Discovery is disabled Serial0 is administratively down, line protocol is down Internet address is 198.135.2.49, subnet mask is 255.255.255.0 Broadcast address is 255.255.255.255 Address determined by setup command MTU is 1500 bytes Helper address is not set Directed broadcast forwarding is enabled Multicast groups joined: 224.0.0.1 224.0.0.2 Outgoing access list is not set Inbound access list is not set Proxy ARP is enabled Security level is default Split horizon is enabled ICMP redirects are always sent ICMP unreachables are always sent ICMP mask replies are never sent IP fast switching is enabled IP fast switching on the same interface is disabled IP SSE switching is disabled Router Discovery is disabled IP accounting is disabled TCP/IP header compression is disabled Probe proxy name replies are disabled Gateway Discovery is disabled

The following is sample output from the show ip interface brief command:

Router# show ip interface brief Interface IP-Address OK? Method Status Protocol Ethernet0 1.0.46.10 YES manual administratively down down PCbus0 198.135.1.43 YES manual administratively down down Serial0 198.135.2.49 YES manual administratively down down

The following is sample output from the show ip interface brief pcbus 0 command:

Router# show ip interface brief pcbus 0 Interface IP-Address OK? Method Status Protocol PCbus0 198.135.1.43 YES manual administratively down down
Related Command

show interfaces

show snapshot

To display snapshot routing parameters associated with an interface, use the show snapshot EXEC command.

show snapshot [interface]
Syntax Description
interface (Optional) Interface type and number.
Command Mode

EXEC

Sample Display

The following is sample output from the show snapshot command:

Router# show snapshot serial 1 Serial1 is up, line protocol is up, snapshot up Options: dialer support Length of each activation period: 3 minutes Period between activations: 10 minutes Retry period on connect failure: 10 For dialer address 240  Current queue: active, remaining active time: 3 minutes  Updates received this cycle: ip, ipx, appletalk For dialer address 1  Current queue: client quiet, time until next activation: 7 minutes

Table 6-21 explains the fields in the display.


Show Snapshot Fields
Field Description
Serial1 is up, line protocol is up Indicates whether the interface hardware is currently active (whether carrier detect is present) and if it has has been taken down by an administrator.
snapshot up Indicates whether the snapshot protocol is enabled on the interface.
Options: Options configured on the snapshot client or snapshot server interface configuration command. It can be one of the following:

  • dialer support--Snapshot routing is configured with the dialer keyword.

  • stay asleep on carrier up--Snapshot routing is configured with the suppress-statechange-update keyword.

Length of each activation period

Length of the active period.
Period between activations Length of the quiet period.
Retry period on connect failure Length of the retry period.
For dialer address Displays information about each dialer rotary group configured with the dialer map command.
Current queue: Indicates which period snapshot routing is currently in. It can be one of the following:

  • active--Routing updates are being exchanged.

  • client quiet--The client router is in a quiet period and routing updates are not being exchanged.

  • server quiet--The server router is in a quiet period, awaiting an update from the client router before awakening, and routing updates are not being exchanged.

  • post active--Routing updates are not being exchanged. If the server router receives an update from the client router, it processes it but does not begin an active period. This allows time for resynchronization of active periods between the client and server routers.

  • no queue--This is a temporary holding queue for new snapshot routing interfaces and for interfaces being deleted.

remaining active time
time until next activation

Time remaining in the current period.
Updates received this cycle Protocols from which routing updates have been received in the current active period. This line is displayed only if the router is in an active period.

shutdown

To disable an interface, use the shutdown interface configuration command. Use the no form of this command to restart a disabled interface.

shutdown
no shutdown
Syntax Description

This command has no arguments or keywords.

Default

Enabled

Command Mode

Interface configuration

Usage Guidelines

The shutdown command disables all functions on the specified interface. On serial interfaces, this command causes the DTR signal to be dropped. On Token Ring interfaces, this command causes the interface to be deinserted from the ring.

This command also marks the interface as unavailable. To check whether an interface is disabled, use the EXEC command show interfaces. An interface that has been shut down is shown as administratively down in the display from this command.

Examples

The following example turns off Ethernet interface 0:

interface ethernet 0 shutdown

The following example turns the interface back on:

interface ethernet 0 no shutdown
Related Command

show interfaces

snapshot client

To configure a client router for snapshot routing, use the snapshot client interface configuration command. To disable a client router, use the no form of this command

snapshot client active-time quiet-time [suppress-statechange-updates] [dialer]
no snapshot client active-time quiet-time [suppress-statechange-updates] [dialer]
Syntax Description
active-time Amount of time, in minutes, that routing updates are regularly exchanged between the client and server routers. This can be an integer in the range 5 to 100. There is no default value. A typical value would be 5 minutes.
quiet-time Amount of time, in minutes, that routing entries are frozen and remain unchanged between active periods. Routes are not aged during the quiet period, so they remain in the routing table as if they were static entries. The argument quiet-time can be a value from 8 to 100000. There is no default value. The minimum quiet time is generally the active time plus 3.
suppress-statechange-updates (Optional) Disables the exchange of routing updates each time the line protocol goes from "down" to "up" or from "dialer spoofing" to "fully up."
dialer (Optional) Allows the client router to dial up the remote router in the absence of regular traffic.
Default

Snapshot routing is disabled.

The active-time and quiet-time arguments have no default values.

Command Mode

Interface configuration

Usage Guidelines

The value of the active-time argument must be the same for the client and server routers.

Example

The following example configures a client router for snapshot routing:

interface dialer 1 snapshot client 5 600 suppress-statechange-updates dialer
Related Commands

clear snapshot quiet-time
dialer map
show snapshot
snapshot server

snapshot server

To configure a server router for snapshot routing, use the snapshot server interface configuration command. To disable a server router, use the no form of this command.

snapshot server active-time [dialer]
no snapshot server active-time [dialer]
Syntax Description
active-time Amount of time, in minutes, that routing updates are regularly exchanged between the client and server routers. This can be an integer in the range 5 to 100. There is no default value. A typical value would be 5 minutes.
dialer (Optional) Allows the client router to dial up the remote router in the absence of regular traffic.
Default

Snapshot routing is disabled.

The active-time argument has no default value.

Command Mode

Interface configuration

Usage Guidelines

The value of the active-time argument must be the same for the client and server routers.

Example

The following example configures a server router for snapshot routing:

interface dialer 1 snapshot server 5
Related Commands

show snapshot
snapshot client

systat

To display information about the active ports of the communication server, enter the systat EXEC command.

systat [all]
Syntax Description
all (Optional) Displays information for both active and inactive ports.
Command Mode

EXEC

Example

The following example shows how to use the systat command:

cs> systat Line   User Host(s) Idle Location 0 con 0 1 tty 1  charnel console 2 tty 2  T2500 #1-1 3 tty 3 T2500 #1-2 4 tty 4 xyz LANE 56 T2500 #1-3 5 tty 5 T2500 #1-4 6 tty 6 3262 #A1 7 tty 7 train   ABC 0 3262 #B1 8 tty 8 3262 #A2 9 tty 9 pzwt XRemote: 6 clients 0 3262 #B2

The information displayed includes the line number, connection name, idle time, and terminal location.

transmitter-delay

To specify a minimum dead-time after transmitting a packet, use the transmitter-delay interface configuration command. Use the no form of this command to restore the default.

transmitter-delay microseconds
no transmitter-delay
Syntax Description
microseconds Approximate number of microseconds of minimum delay after transmitting a packet on the MCI and SCI interface cards
Default

0 microseconds

Command Mode

Interface configuration

Usage Guidelines

This command is especially useful for serial interfaces that can send back-to-back data packets over serial interfaces faster than some hosts can receive them.

The transmitter delay feature is implemented for the following Token Ring cards: CSC-R16M, CSC-1R, and CSC-2R. For the first four cards, the command syntax is the same as the existing command and specifies the number of milliseconds to delay between sending frames that are generated by the communication server. Transmitter delay for the CSC-CTR uses the same syntax, but specifies a relative time interval to delay between transmission of all frames.

Example

The following example specifies a delay of 300 microseconds on interface serial interface 0:

interface serial 0 transmitter-delay 300

tunnel checksum

To enable encapsulator-to-decapsulator checksumming of packets on a tunnel interface, use the tunnel checksum interface configuration command. Use the no form of this command to disable checksumming.

tunnel checksum
no tunnel checksum
Syntax Description

This command has no arguments or keywords.

Default

No tunnel checksumming

Command Mode

Interface configuration

Usage Guidelines

This command currently applies to generic route encapsulation (GRE) only. Some passenger protocols rely on media checksums to provide data integrity. By default, the tunnel does not guarantee packet integrity. By enabling end-to-end checksums, the communication servers will drop corrupted packets.

Example

In the following example, all protocols will have encapsulator-to-decapsulator checksumming of packets on the tunnel interface:

tunnel checksum

tunnel destination

To specify a tunnel interface's destination, use the tunnel destination interface configuration command. Use the no form of this command to remove the destination.

tunnel destination {hostname | ip-address}
no tunnel destination
Syntax Description
hostname Name of the host destination
ip-address IP address of the host destination
Default

No tunnel interface destination is specified.

Command Mode

Interface configuration

Usage Guidelines

You cannot have two tunnels using the same encapsulation mode with exactly the same source and destination address. The workaround is to create a loopback interface and source packets off of the loopback interface.

Example

In the following example, the tunnel destination is 131.222.111.234:

tunnel destination 131.222.111.234
Related Command

tunnel source

tunnel key

To enable an ID key for a tunnel interface, use the tunnel key interface configuration command. Use the no form of this command to remove the ID key.

tunnel key key-number
no tunnel key
Syntax Description
key-number Integer from 0 to 4294967295
Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command currently applies to generic route encapsulation (GRE) only. Tunnel ID keys can be used as a form of weak security to prevent misconfiguration or injection of packets from a foreign source.


Note When using GRE, the ID key is carried in each packet. We do not recommend relying on this key for security purposes.
Example

In the following example, the tunnel key is set to 3:

tunnel key 3

tunnel mode

To set the encapsulation mode for the tunnel interface, use the tunnel mode interface configuration command. To set to the default, use the no form of this command.

tunnel mode {aurp | cayman | eon | gre ip | mbone | nos}
no tunnel mode
Syntax Description
aurp AppleTalk Update Routing Protocol (AURP)
cayman Cayman TunnelTalk AppleTalk encapsulation
dvmrp Distance Vector Multicast Routing Protocol
eon EON compatible CLNS tunnel
gre ip Generic route encapsulation (GRE) protocol over IP
nos KA9Q/NOS compatible IP over IP
Default

GRE tunneling

Command Mode

Interface configuration

Usage Guidelines

You cannot have two tunnels using the same encapsulation mode with exactly the same source and destination address. The workaround is to create a loopback interface and source packets off of the loopback interface.

Cayman tunneling implements tunneling as designed by Cayman Systems. This enables our routers to interoperate with Cayman GatorBoxes. With Cayman tunneling, you can establish tunnels between two routers or between our router and a GatorBox. When using Cayman tunneling, you must not configure the tunnel with an AppleTalk network address. This means that there is no way to ping the other end of the tunnel.

Use DVMRP when a router connects to a mrouted router to run DVMRP over a tunnel. It is required to configure Protocol-Independent Multicast (PIM) and an IP address on a DVMRP tunnel.

Generic route encapsulation (GRE) tunneling can be done between our routers only. When using GRE tunneling for AppleTalk, you configure the tunnel with an AppleTalk network address. This means that you can ping the other end of the tunnel.

Examples

The following example enables Cayman tunneling:

interface tunnel0 tunnel source ethernet0 tunnel destination 131.108.164.19 tunnel mode cayman

The following example enables GRE tunneling:

interface tunnel0 appletalk cable-range 4160-4160 4160.19 appletalk zone Engineering tunnel source ethernet0 tunnel destination 131.108.164.19 tunnel mode gre ip
Related Commands

tunnel destination
tunnel source

tunnel sequence-datagrams

To configure a tunnel interface to drop datagrams that arrive out of order, use the tunnel sequence-datagrams interface configuration command. Use the no form of this command to disable this function.

tunnel sequence-datagrams
no tunnel sequence-datagrams
Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command currently applies to generic route encapsulation (GRE) only. This command is useful when carrying passenger protocols that behave poorly when they receive packets out of order (for example, LLC2-based protocols).

Example

In the following example, the tunnel is configured to drop datagrams that arrive out of order:

tunnel sequence-datagrams

tunnel source

To set a tunnel interface's source address, use the tunnel source interface configuring command. Use the no form of this command to remove the source address.

tunnel source {ip-address | interface-type interface-number}
no tunnel source
Syntax Description
ip-address IP address to use as the source address for packets in the tunnel.
interface-type All types.
interface-number Specifies the port, connector, or interface card number. The numbers are assigned at the factory at the time of installation or when added to a system, and can be displayed with the show interfaces command.
Default

No tunnel interface's source address is set.

Command Mode

Interface configuration

Usage Guidelines

You cannot have two tunnels using the same encapsulation mode with exactly the same source and destination address. The workaround is to create a loopback interface and source packets off of the loopback interface.

When using tunnels to Cayman boxes, you must set the tunnel source to an explicit IP address on the same subnet as the Cayman box, not the tunnel itself.

Examples

In the following example, the tunnel source is set to the IP address assigned to Ethernet interface 0:

tunnel source ethernet 0

The following example enables Cayman tunneling:

interface tunnel0 tunnel source ethernet0 tunnel destination 131.108.164.19 tunnel mode cayman

The following example enables GRE tunneling:

interface tunnel0 appletalk cable-range 4160-4160 4160.19 appletalk zone Engineering tunnel source ethernet0 tunnel destination 131.108.164.19 tunnel mode gre ip
Related Commands

tunnel destination
tunnel source

tx-queue-limit

To control the number of transmit buffers available to a specified interface on the MCI and SCI cards, use the tx-queue-limit interface configuration command.

tx-queue-limit number
Syntax Description
number Maximum number of transmit buffers that the specified interface can subscribe
Default

Defaults depend on the total transmit buffer pool size and the traffic patterns of all the interfaces on the card. Defaults and specified limits are displayed with the show controllers mci EXEC command.

Command Mode

Interface configuration

Usage Guidelines

Only use this command under the guidance of a technical support representative.

Example

The following example sets the maximum number of transmit buffers on the interface to 5:

interface ethernet 0 tx-queue-limit 5
Related Command

show controllers mci

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