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This section lists dial-on-demand routing (DDR) commands, explains the command syntax, and provides usage guidelines. For information about configuring DDR and configuration examples, refer to the "Configuring DDR" chapter in the Router Products Configuration Guide.
To define how much time should elapse before a secondary line status changes after a primary line status has changed, use the backup delay interface configuration command. To return to the default, which means as soon as the primary fails, the secondary is immediately brought up without delay, use the no form of this command.
backup delay {enable-delay | never} {disable-delay | never}| enable-delay | Number of seconds that elapse after the primary line goes down before the router activates the secondary line. |
| disable-delay | Number of seconds that elapse after the primary line goes up before the router deactivates the secondary line. |
| never | Prevents the secondary line from being activated or deactivated. |
0 seconds
Interface configuration
For environments in which there are spurious signal disruptions that may appear as intermittent lost carrier signals, it is recommended that some delay be enabled before activating and deactivating a secondary line.
The following example sets a 10-second delay on deactivating the secondary line (interface serial 0); however, the line is activated immediately:
interface serial 0
backup delay 0 10
To configure the serial interface as a secondary or dial backup line, use the backup interface interface configuration command. To disable this feature, use the no form of this command.
backup interface interface number| interface | Type of interface. It must be serial. |
| number | Serial port to be set as the secondary line. |
Disabled
Interface configuration
The interface you define with this command can only backup one interface.
The following example sets serial 1 as the backup line:
interface serial 1
backup interface serial 1
To set traffic load threshold for dial backup service, use the backup load interface configuration command. To return to the default value, use the no form of this command.
backup load {enable-load | never} {disable-load | never}| enable-load | Percentage of the primary line's available bandwidth. |
| disable-load | Percentage of the primary line's available bandwidth. |
| never | Sets the secondary line to never be activated due to traffic load. |
No threshold is predefined.
Interface configuration
When the transmitted or received load on the primary line is greater than the value assigned to the enable-load argument, the secondary line is enabled.
The secondary line is disabled when one of the following conditions occur:
If the never keyword is used instead of an enable-threshold value, the secondary line is never activated because of a traffic load. If the never keyword is used instead of a disable-load argument, the secondary line is never activated because of traffic load.
The following example sets the traffic load threshold to 60 percent of the primary line serial 0. 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
To create a script that will place a call over a modem, use the chat-script global configuration command. To disable the specified chat script, use the no form of this command.
chat-script script-name expect-send| script-name | Name of the chat script |
| expect-send | Content of the chat script |
No chat scripts are configured.
Global configuration
Chat scripts are used in dial-on-demand routing to give commands to dial a modem and commands to log on to remote systems. The defined script will be used to place a call over a modem.
Some characteristics of chat scripts are as follows:
It is recommended that one chat script (a "modem" chat script) be written for placing a call and another chat script (a "system" or "login" chat script) be written to log onto remote systems, where required.
A suggested chat script naming convention is as follows:
vendor-type-modulationIn other words, the syntax of the chat-script command becomes the following:
chat-script vendor-type-modulation expect sendFor example, if you have a Telebit T3000 modem that uses V.32bis modulation, you would name your chat script as follows:
telebit-t3000-v32bis
For example, the chat-script command could become the following:
chat-script telebit-t3000-v32bis ABORT ERROR ABORT BUSY ABORT "NO ANSWER" "" "AT H" OK "AT DT \T" DIALING \c TIMEOUT 30 CONNECT \c
For example, you could have script names like the following
Adhering to this naming convention allows you to use partial chat script names with regular expressions to specify a range of chat scripts that can be used. This is particularly useful for dialer rotary groups and is explained further in the next section.
Chat scripts are in the form expect send, where the send string following the hyphen is executed if the preceding expect string fails. Each send string is followed by a return unless it ends with \c. ^x gets translated into the appropriate control character, and \x gets translated into x if \x is not one of the special sequences listed in Table 8-1.
See the book entitled Managing uucp and Usenet by Tim O'Reilly and Grace Todino for more information about chat scripts.
The escape sequences used in chat scripts are listed in Table 8-1.
| Escape Sequence | Description |
|---|---|
| "" | Expect a null string. |
| EOT | Send an end-of-transmission character. |
| BREAK | Cause a BREAK. This is sometimes simulated using line speed changes and null characters. May not work on all systems. |
| \c | Suppress newline at the end of the send string. |
| \d | Delay for 2 seconds. |
| \K | Insert a BREAK. |
| \n | Send a newline or linefeed character. |
| \p | Pause for 1/4 second |
| \r | Send a return. |
| \s | Send a space character. |
| \t | Send a table character |
| \\ | Send a backslash (\) character. |
| \T | Replaced by phone number. |
| \q | Reserved, not yet used |
Sample supported expect-send pairs are described in Table 8-2.
| Expect and Send Pair | Function |
|---|---|
| ABORT string | Starts scanning for the string in the input and if it is seen this indicates that the chat script has failed. |
| TIMEOUT time | Sets the time to wait for input, in seconds. The default is five seconds. |
As an example of how expect-send pairs function, if the modem reports BUSY when the number is busy, you can indicate that you want the attempt stopped at this point by including ABORT BUSY in your chat script.
ABORT sink instead of ABORT ERROR means that the system will abort when it sees sink instead of when it sees ERROR.
After the connection is established and Return is pressed, a second Return is often required before the prompt appears.
You might include the following as part of your chat script:
ssword:-/r-ssword
This means that after the connection is established you want "ssword" to be displayed. If it is not displayed, send a return again after the timeout passes.
The following example shows the chat-script command being used to create a chat script named t3000:
chat-script t3000 ABORT ERROR ABORT BUSY ABORT "NO ANSWER" "" "AT H" OK "AT DT \T" DIALING \c TIMEOUT 30 CONNECT \c
dialer map
modem chat-script
To set the length of time an interface stays down after a call has completed or failed, before it is available to dial again, use the dialer enable-timeout interface configuration command. To return to the default value, use the no form of this command.
dialer enable-timeout seconds| seconds | Time in seconds that the router waits before the next call can occur on the specific interface. Acceptable values are positive, nonzero integers. |
15 seconds
Interface configuration
This command applies to inbound and outbound calls.
If your phone lines are busy or down, you might want to enforce a certain period of time before the system repeats an attempt to make a connection with a remote site. Configuring this timeout can prevent outgoing lines and switching equipment from being needlessly loaded down.
The following example specifies a waiting period of 30 seconds on interface async 1:
interface async 1
dialer enable-timeout 30
To specify the amount of time that a line for which there is contention will stay idle before the line is disconnected and the competing call is placed, use the dialer fast-idle interface configuration command. To return to the default value, use the no form of this command.
dialer fast-idle seconds| seconds | Idle time, in seconds, that must occur on an interface before the line is disconnected. Acceptable values are positive, nonzero integers. |
20 seconds
Interface configuration
The fast idle timer is activated if there is contention for a line. In other words, if a line is busy, a packet for a different next hop address is received, and the busy line is required to send the competing packet, the dialer fast idle timer is activated.
If the line becomes idle for configured length of time, the current call is disconnected immediately and the new call is placed.
If the line has not yet been idle as long as the fast idle timer, the packet is dropped because there is no way to get through to the destination. After the packet is dropped, the fast idle timer remains active and the current call is disconnected as soon as it has been idle for as long as the fast idle timeout.
If, in the meanwhile, there is another packet transmitted to the currently connected destination, and it is classified as interesting, the fast idle timer will be restarted.
This command applies to inbound and outbound calls.
Combining this command with the dialer idle-timeout command allows you to configure lines to stay up for a longer period of time when there is not contention, but to be reused more quickly when there are not enough lines for the current demand.
The following example specifies a fast idle timeout of 35 seconds on interface async 1:
interface async 1
dialer fast-idle 35
dialer idle-timeout
dialer map
To control access, use the dialer-group interface configuration command. To remove an interface from the specified dialer access group, use the no form of this command.
dialer-group group-number| group-number | Number of the dialer access group to which the specific interface belongs. This access group is defined using the dialer-list command. Acceptable values are nonzero, positive integers between 1 and 10. |
No access is predefined.
Interface configuration
An interface can only be associated with a single dialer access group; multiple dialer-group assignment is not allowed. A second dialer access group assignment will override the first. A dialer access group is defined with the dialer-group command. The dialer-list command associates an access list with a dialer access group.
The following example specifies dialer access group number 1.
If there is a dialer-list command associated with the dialer group 1, the destination address of the packet is evaluated against the access list specified in the associated dialer-list command. If it passes, a call is initiated (if no connection has already been established) or the idle timer is reset (if a call is currently connected).
interface async 1
dialer-group 1
dialer-list
To specify the idle time before the line is disconnected, use the dialer idle-timeout interface configuration command. To reset the idle timeout to the default, use the no form of this command.
dialer idle-timeout seconds| seconds | Idle time, in seconds, that must occur on an interface before the line is disconnected. Acceptable values are positive, nonzero integers. |
120 seconds
Interface configuration
This command is used on lines for which there is no contention. When contention occurs, the dialer fast-idle command is activated. For example, when a busy line is requested to send another packet to a different destination than it is currently connected to, line contention occurs and the dialer fast-idle command is activated.
This command applies to inbound and outbound calls. For example, if a receiving system needs to make outgoing calls, you might configure it with a short idle timeout.
The following example specifies of an idle timeout of 3 minutes (180 seconds) on interface async 1:
interface async 1
dialer idle-timeout 180
dialer fast-idle
To specify that DDR is to be supported, use the dialer in-band interface configuration command. To disable dial-on-demand routing for the interface, use the no form of this command.
dialer in-band [no-parity | odd-parity]| no-parity | (Optional) Indicates that no parity is to be applied to the dialer string that is sent out to the modem on synchronous interfaces. |
| odd-parity | (Optional) Indicates that the dialed number has odd parity (7-bit ASCII characters with the eighth bit the parity bit) on synchronous interfaces. |
Disabled. By default, no parity is applied to the dialer string.
Interface configuration
The dialer in-band command specifies that chat scripts will be used on the auxiliary port and V.25bis will be used on synchronous interfaces.
The parity keywords do not apply to asynchronous interfaces.
The parity setting applies to the dialer string that is sent out to the modem. If you do not specify a parity, or if you specify no parity, no parity is applied to the output number. If odd parity is configured, the dialed number will have odd parity (7-bit ASCII characters with the eighth bit, the parity bit.)
If an interface is only accepts calls and does not place calls, the dialer in-band interface configuration command is the only command needed to configure it. If an interface is configured in this manner, with no dialer rotary groups, the idle timer never disconnects the line. It is up to the remote end (the end that placed the call) to disconnect the line based on idle time.
The following example specifies DDR for asynchronous interface 1:
interface async 1
dialer in-band
dialer map
dialer string
To group access lists, use the dialer-list list global configuration command. To disable automatic dialing, use the no form of this command.
dialer-list dialer-group list access-list-number| dialer-group | Specifies the number of a dialer access group identified in any dialer-group interface configuration command. |
| access-list-number | Specifies the access list number specified in any IP or Novell IPX access lists including Novell IPX extended, Service Access Point (SAP) access lists and bridging type. See Table 8-3 in the "Usage Guidelines" section for the supported access list types and numbers. |
None
Global configuration
The dialer-list list command applies access lists to dialer access groups to control automatic dialing using DDR with standard IP access lists. This command applies access lists to dialer access groups defined with the dialer-group command. See the Router Products Configuration Guide for more information about configuring IP access lists.
Table 8-3 lists the access list types and numbers that the dialer-group command supports.
| Access List Type | Access List Number Range |
|---|---|
| Standard IP | 1-99 |
| Extended IP | 100-199 |
| Transparent Bridging | 200-299 |
| Standard Novell IPX | 800-899 |
| Extended Novell IPX | 900-999 |
In the following example, dialing occurs when an interesting packet (one that matches access list specifications) needs to be output on an interface. Using the standard access list method, packets can be classified as interesting or uninteresting. To specify that IGRP TCP/IP routing protocol updates are not interesting (relative to DDR automatic dialing), the following access list would be defined:
access-list 101 deny igrp 0.0.0.0 255.255.255.255 255.255.255.255 0.0.0.0
To permit all other IP traffic, the preceding would be modified as follows:
access-list 101 permit ip 0.0.0.0 255.255.255.255 0.0.0.0 255.255.255.255
Then the following command would be used to place list 101 into dialer access group 1:
dialer-list 1 list 101
dialer-group
To control automatic dialing by a protocol name, use the dialer-list protocol global configuration command. To disable automatic dialing, use the no form of this command.
dialer-list dialer-group protocol protocol-name {permit | deny}| dialer-group | Number of a dialer access group identified in any dialer access group interface configuration command |
| protocol-name | One of the supported protocols as listed in Table 8-4 in the "Usage Guidelines" section |
| permit | (Optional) Permit access to an entire protocol. |
| deny | (Optional) Deny access to an entire protocol. |
None
Global configuration
Using the dialer-list protocol command provides a coarse method of access control by permitting or denying an entire protocol. For more refined access control, use the dialer-list list command to specify an access list.
Table 8-4 lists the protocols supported for DDR access lists.
| Keyword | Protocol |
|---|---|
| ip | IP |
| ipx | Novell IPX |
dialer-group
dialer-list list
To configure bandwidth on demand by setting the maximum load before the dialer places another call to a destination, use the dialer load-threshold interface subcommand. To disable the setting, use the no form of the command.
dialer load-threshold load| load | Interface load beyond which the dialer will initiate another call to the destination. This argument is a number between 1 and 255. For example, a value of 128 means 50%; a value of 255 means 100%. |
No maximum load is predefined.
Interface configuration
This command applies to dialer rotary groups only.
If a packet is transmitted on a dialer interface, there is a call established, and the transmit load on the interface exceeds the specified load threshold, the dialer will initiate another call to the destination. The dialer will make additional calls as necessary to expand bandwidth but will never interrupt an existing call to another destination.
The argument load is the calculated weighted average load value for the interface; 1 is unloaded, 255 is fully loaded. The load is calculated by the system dynamically, based on bandwidth. You must set the bandwidth for an interface in kilobits per second, using the bandwidth command.
The load calculation determines how much of the total bandwidth you are using, where 255 means that you are using one hundred percent of the bandwidth.
See the interface configuration chapter for a full description of the bandwidth command.
In the following example, if the load to a particular destination on an interface in dialer rotary group 5 exceeds interface load 200, the dialer will initiate another call to the destination.
interface dialer 5
dialer load-threshold 200
A dagger (+) indicates that the command is documented in another chapter.
bandwidth +
interface dialer
dialer rotary-group
To configure a serial interface to call one or multiple sites, use the dialer map interface configuration command. To place a call to a single site on an asynchronous line for which a modem script has not been assigned or a system script must be specified, or to multiple sites on a single line, multiple lines, or a dialer rotary group, use the first form of the dialer map command. To place a call to multiple sites and to authenticate calls from multiple sites, use the second form of the dialer map command. To delete a particular dialer map entry, use the no form of this command.
dialer map protocol next-hop-address [modem-script modem-regexp]No maps are predefined.
Interface configuration
Specify chat scripts for a physical interface that is not part of a dialer rotary group if no chat script is specified for the line or an additional (system) chat script is required to log on to the remote system.
Configure a dialer map command for each remote destination for that interface.
You do not need to specify a system script under the following conditions:
If you adhere to the chat script naming convention suggested in this publication, use the form [modem-script *modulation-type] in the dialer map command; for example, ".*-v32bis." This allows you to specify the modulation type that is best for the system you are calling, and allows the modem type for the line to be specified by the modem chat-script command.
The expression "." is a wildcard that matches any character, and the expression "*" indicates that the preceding character can be duplicated multiple times. For more information about regular expressions, see the "Regular Expressions" appendix.
If there is a modem-script specified in the dialer map interface configuration command and a modem script specified in the modem chat-script line configuration command, the first chat script that matches both will be used. If no script matches both, an error message is logged and the connection is not established. If there is no modem chat script specified for the line, the first chat script (that is, the one specified using the chat-script global configuration command) that matches the modem script regular expression will be used. If there is a system script specified in the dialer map interface configuration command, the first chat script to match the regular expression will be used.
The modem-script and system-script keywords and corresponding arguments are optional. They are ignored on synchronous interfaces.
If you have named your chat script according to the type of modem and modulation (for example, codex-v32 or telebit v32), your regular expression could be codex-.* in the modem chat-script line configuration command, and *-v32bis in the modem script specified in the dialer map command for a system that you wish to connect to using v32bis modulation.
The modem lines (specified by the argument regexp in the modem chat-script line configuration command) would be set to one of the following regular expressions to match patterns, depending on what kind of modem you have:
With an interface configured for Challenge Handshake Authentication Protocol (CHAP) or Password Authentication Protocol (PAP) and configured with the name hostname keyword and argument pair, the local device authenticates the remote site using CHAP, which transmits the remote site's host name to the central site. The central site then uses this name to authenticate the caller and uses the next hop address to transmit packets to the remote site. Because no dialer string is specified, the central site cannot call the remote router.
The following example shows a dialing chat script and a login chat script. The dialer in-band command enables DDR on asynchronous interface 10 and the dialer map command looks for the specified dialing and the login scripts, and then uses those scripts to dial 96837890.
chat-script dial ABORT ERROR "" "AT Z" OK "ATDT \T" TIMEOUT 30 CONNECT \c
chat-script login ABORT invalid TIMEOUT 15 name: billw word: wewpass ">"
"slip default"
interface async 10
dialer in-band
dialer map ip 10.55.0.1 modem-script dial system-script login 96837890
In the following example, the remote site is calling the central site, and the central site is calling the remote site. The central router can use the name, ZZZ, to authenticate the remote router when they connect and also can use the dialer string 14155553434 to call the remote router if it is not currently connected.
interface async 1
dialer map ip 131.108.2.5 name ZZZ 14155553434
A dagger (+) indicates that the command is documented in another chapter.
chat-script
modem chat-script
ppp authentication chap +
ppp authentication pap +
username
To configure a dialer rotary group to receive and take advantage of caller identification using CHAP, use the dialer map name interface configuration command. To delete a dialer map entry, use the no form of this command.
dialer map protocol next-hop-address name hostname| protocol | Name of the protocol |
| next-hop-address | Protocol address used to match against addresses to which packets are destined |
| hostname | Name or ID of the remote device (usually the host name) |
No dialer map is configured.
Interface configuration
Use the dialer map name command in configurations in which remote sites are calling a central site, but the central site is not calling the remote site. With this command, the local device will authenticate the remote site using CHAP or PAP, which will transmit the remote site's host name to the central site. The central site will then use this name to authenticate the caller, and will use the next hop address to transmit packets to the remote site. Because there is no dialer string specified, the central site cannot call the remote router.
For routers with ISDN interfaces, if calling line identification (CLI/ANI/caller ID) is provided, the hostname field may contain the number that calling line ID provides.
In the following example, a remote site is calling a central site, but the central site is not calling the remote site. The local device will authenticate the site that is calling in using CHAP. CHAP will cause the remote site's name, YYY, to be transmitted to the site it is calling. The central site will then use this name to authenticate the remote site.
interface async 1
encapsulation ppp
ppp authentication chap
dialer map ip 131.108.2.5 name YYY
dialer map
ppp authentication chap
ppp authentication pap
username
Use the dialer map speed interface configuration command to set the dialer map speed. Use the no form of this command to set the default dialer map speed.
dialer map protocol next-hop-address speed speed| protocol | Name of the protocol. |
| next-hop-address | Protocol address used to match against addresses to which packets are destined. |
| speed | Dialer speed. It can be either 56 (for 56 kbps) or 64 (for 64 kbps). The default is 64 kbps. |
64 kbps
Interface configuration
For ISDN interfaces only, you can specify an optional speed parameter for dialer map commands if you also specify a dial string. This option informs the ISDN software whether it should place a call at 56 or 64 kbps. If you omit the ISDN speed parameter, the default is 64 kbps.
In the following example, the dialer speed is set at 56 kbps to call a remote site at 131.108.2.5.
interface async 1
encapsulation ppp
ppp authentication chap
dialer map ip 131.108.2.5 speed 56
dialer map
dialer map name
ppp authentication chap
ppp authentication pap
username
To include an interface in a dialer rotary group, use the dialer rotary-group interface configuration command.
dialer rotary-group number| number | Number of the dialer interface in whose rotary group you want this interface included. An integer that you select that indicates the dialer rotary group; defined by the interface dialer command. A number from 0 to 255. |
No interfaces are included in a dialer rotary group.
Interface configuration
The following example places async interfaces1 and 2 into dialer rotary group 1, defined by the interface dialer 1 command:
hostname central-site
! PPP encapsulation is enabled for interface dialer 1.
interface dialer 1
encapsulation ppp
dialer in-band
ip address 131.108.2.1 255.255.255.0
ip address 131.126.4.1 255.255.255.0 secondary
! The first dialer map command allows the central site and remote site YYY
! and to call each other and allows the central site to authenticate site YYY
! when it calls in. The second dialer map command, with no! dialer string,
! allows the central site to authenticate remote site ZZZ when it calls in, but
! the central site cannot call remote site ZZZ (no phone number).
dialer map ip 131.108.2.5 name YYY 14155553434
dialer map ip 131.126.4.5 name ZZZ
! The DTR pulse signals for three seconds on the interfaces in dialer
! group 1. This holds the DTR low so the modem can recognize that DTR has been
! dropped.
pulse-time 3
! Interfaces async 1 and async 2 are placed in dialer rotary group 1.
! All of the interface configuration commands (the encapsulation and dialer
! map commands shown earlier in this example) applied to interface
! dialer 1 apply to the physical interfaces assigned to the dialer group.
interface async 1
dialer rotary-group 1
interface async 2
dialer rotary-group 1
interface dialer
To specify the string (telephone number) to be called for interfaces calling a single site, use the dialer string interface configuration command. To delete the dialer string specified for the interface, use the no form of this command.
dialer string dial-string| dial-string | String of characters to be sent to a DCE |
No strings are predefined.
Interface configuration
To use this command on an asynchronous interface, a modem chat script must be defined for the associated line, by using the modem chat-script command. A script must be used to implement dialing.
Dialers configured as in-band pass the string to the external dialing device. Specify one dialer string command per interface.
To specify multiple strings, use the dialer map command. In general, you include a dialer string or dialer map command if you intend to use a specific interface to initiate a DDR call.
The string of characters specified for the dial-string argument is the default number used under the following conditions:
On synchronous interfaces, depending on the type of modem you are using, International Telecommunication Union Telecommunication (ITU-T) Standardization Sector V.25bis options might be supported as dial-string parameters of the dialer string command. Supported options are listed in Table 8-5. The functions of the parameters are nation specific, and they may have different implementations in your country. These options apply only if you have enabled DDR with the dialer in-band command. Refer to the operation manual for your modem for a list of supported options.
| Option | Description |
|---|---|
| : | Wait tone. |
| < | Pause.
Usage and duration of this parameter vary by country. |
| = | Separator 3.
For national use. |
| > | Separator 4
For national use. |
| P | Dialing to be continued in pulse mode.
Optionally accepted parameter. |
| T | Tone (Dialing to be continued in Dual Tone Multifrequency, DTMF, mode).
Optionally accepted parameter. |
| & | Flash. (The flash duration varies by country.)
Optionally accepted parameter. |
The following example specifies a DDR telephone number to be tone dialed on interface async 1 using the dialer string command:
interface async 1
dialer string T14085553434
dialer-group
dialer in-band
dialer map
modem chat-script
To specify how long to wait for a carrier, use the dialer wait-for-carrier-time interface configuration command. To reset the carrier wait time value to the default, use the no form of this command.
dialer wait-for-carrier-time seconds| seconds | Number of seconds that the interface waits for the carrier to come up when a call is placed. Acceptable values are positive, nonzero integers. |
30 seconds
Interface configuration
On asynchronous interfaces, the dialer wait-for-carrier-time command sets the total time allowed for the chat script to run.
If a carrier signal is not detected in this amount of time, the interface is disabled until the enable timeout occurs (configured with the dialer enable-timeout command).
The following example specifies a carrier wait time of 45 seconds on interface async 1:
interface async 1
dialer wait-for-carrier-time 45
dialer enable-timeout
To configure Point-to-Point Protocol (PPP) encapsulation, use the encapsulation ppp interface configuration command.
encapsulation pppThis command has no arguments or keywords.
Disabled
Interface configuration
The Point-to-Point Protocol (PPP), described in RFCs 1331 and 1332, is designed to encapsulate Internet Protocol (IP) datagrams and other network layer protocol information over point-to-point links.
PPP echo requests also can be used as keepalives, to minimize disruptions to the end users of your network. The no keepalive command can be used to disable echo requests.
The following example enables PPP encapsulation on interface async 1:
interface async 1
encapsulation ppp
A dagger (+) indicates that the command is documented in another chapter.
keepalive +
ppp authentication chap
ppp authentication pap
To define a dialer rotary group, use the interface dialer global configuration command.
interface dialer number| number | Number of the dialer rotary group. It can be number in the range 0 through 255. |
No dialer rotary groups are predefined.
Global configuration
Dialer rotary groups allow you to apply a single interface configuration to a set of physical interfaces. This allows a group of interfaces to be used as a pool of interfaces for calling many destinations.
Once the interface configuration is propagated to a set of interfaces, those interfaces can be used to place calls using the standard DDR criteria. When multiple destinations are configured, any of these interfaces can be used for outgoing calls.
Dialer rotary groups are useful in environments that require multiple 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. Interface configuration commands entered after the interface dialer command will be applied to all physical interfaces assigned to specified rotary groups. Individual interfaces in a dialer rotary group do not have individual addresses. The dialer interface has an address, and that address is used by all interfaces in the dialer rotary group.
The following example identifies interface dialer 1 as the dialer rotary group leader. Interface dialer 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
authentication chap
dialer in-band
ip address 1.2.3.4
dialer map ip 1.2.2.5 name YYY 14155553434
dialer map ip 1.3.2.6 name ZZZ
To have the router verify a called-party number or subaddress number in the incoming setup message for ISDN BRI calls, if the number is delivered by the switch, use the isdn answer1 interface configuration command. To remove the verification request, use the no form of this command.
isdn answer1 {called-party-number | subaddress | called-party-number:subaddress}| called-party-number | Telephone number of the called-party. Either the called-party-number or subaddress (or both) must be specified. |
| subaddress | Subaddress number. Either the called-party-number or subaddress (or both) must be specified. A colon separates the called-party-number from the subaddress. |
The router does not verify the called-party or subaddress number.
Interface configuration
If you do not specify the isdn answer1 or isdn answer2 command, all calls are accepted. If you specify this command, the router must verify the incoming called-party number and the subaddress before accepting the call. The verification proceeds from right to left for both the called-party number and subaddress.
It is possible to configure just the called-party number or just the subaddress. In such a case, only that part is verified.
You can declare a digit a "don't care" digit by configuring it as an "x" or "X". In such a case, any incoming digit is allowed.
In the following example, 5552222 is the called-party number and 1234 is the subaddress:
interface bri0
isdn answer1 5552222:1234
isdn answer2
To have the router verify a called-party number or subaddress number in the incoming setup message for ISDN BRI calls, if the number is delivered by the switch, use the isdn answer2 interface configuration command. To remove the verification request, use the no form of this command.
isdn answer2 {called-party-number | subaddress | called-party-number:subaddress}| called-party-number | Telephone number of the called-party. Either the called-party-number or subaddress (or both) must be specified. |
| subaddress | Subaddress number. Either the called-party-number or subaddress (or both) must be specified. A colon separates the called-party-number from the subaddress. |
The router does not verify the called-party or subaddress number.
Interface configuration
If you do not specify the isdn answer1 or isdn answer2 command, all calls are accepted. If you specify this command, the router must verify the incoming called-party number and the subaddress before accepting the call. The verification proceeds from right to left for both the called-party number and subaddress.
It is possible to configure just the called-party number or just the subaddress. In such a case, only that part is verified.
You can declare a digit a "don't care" digit by configuring it as an "x" or "X". In such a case, any incoming digit is allowed.
In the following example, 9991111 is the called-party number, and 9876 is the subaddress:
interface bri0
isdn answer2 9991111:9876
isdn answer1
To set a regular expression for a script on a modem line, use the modem chat-script line configuration command for asynchronous lines.
modem chat-script regexp| regexp | Regular expression to be used to select a chat script. The chat script name will be matched to regexp. |
No regular expressions are predefined.
Line configuration
Scripts are used to give commands to dial modems and commands to log onto remote systems. The regular expression is used to specify the name of the modem script that is to be executed. The first script that matches the argument regexp in this command and the dialer map command will be used. For more information about regular expressions, see the "Regular Expressions" appendix.
If you adhered to the recommended naming convention for chat scripts, the modem lines (the argument regexp in the modem chat-script command) would be set to one of the following regular expressions to match patterns, depending on what kind of modem you have:
In the dialer map command, you could specify the modulation but leave the type of modem unspecified, as in ".*-v32bis."
The following example shows line chat scripts being specified for lines connected to Telebit and U.S. Robotics modems:
! Some lines have telebit modems
line 1 6
modem chat-script telebit.*
! Some lines have US robotics modems
line 7 12
modem chat-script usr.*
chat-script
modem-script
system-script
To enable Challenge Handshake Authentication Protocol (CHAP) on a serial interface, use the ppp authentication chap interface configuration command. To disable this encapsulation, use the no form of this command.
ppp authentication chapThis command has no arguments or keywords.
Disabled
Interface configuration
Once you have enabled CHAP, the local router requires a password from remote devices. If the remote device does not support CHAP, no traffic will be passed to that device.
The following example enables CHAP on interface serial 4:
interface serial 4
encapsulation ppp
ppp authentication chap
encapsulation ppp
ppp authentication pap
To enable Password Authentication Protocol (PAP) on a serial interface, use the ppp authentication pap interface configuration command. To disable this encapsulation, use the no form of this command.
ppp authentication papThis command has no arguments or keywords.
Disabled
Interface configuration
When PAP is enabled, the remote router attempting to connect to the local router is required to send an authentication request. If the username and password specified in the authentication request are accepted, the router sends an authentication acknowledgment.
The following example enables CHAP on interface serial 4:
interface serial 4
encapsulation ppp
ppp authentication pap
encapsulation ppp
ppp authentication chap
To obtain a general diagnostic display for serial interfaces configured for DDR, use the show dialer EXEC command.
show dialer [interface interface unit]| interface | (Optional) Information for the interface specified by the arguments interface and unit is to be displayed. |
| interface unit | (Optional) Interface and unit identifiers. |
EXEC
The following is sample output from the show dialer command.
Router# show dialer int async 1
Async1 - dialer type = IN-BAND NO-PARITY
Idle timer (900 secs), Fast idle timer (20 secs)
Wait for carrier (30 secs), Re-enable (15 secs)
Time until disconnect 838 secs
Current call connected 0:02:16
Connected to 8986
Dial String Successes Failures Last called Last status
8986 0 0 never Default
8986 8 3 0:02:16 Successful
Table 8-6 describes significant fields shown in the display.
| Field | Description |
|---|---|
| Async 1 | Name of an asynchronous interface. |
| dialer type = IN-BAND | Indicates that DDR is enabled. |
| Idle timer (600 secs) | Idle timeout specification (in seconds). |
| Fast idle timer (20 secs) | Fast idle timer specification (in seconds). |
| Wait for carrier (30 secs) | Wait for carrier timer specification (in seconds). |
| Re-enable (15 secs) | Enable timeout specification (in seconds). |
| Time until disconnected | Time until line is configured to disconnect. |
| Current call connected | Time at which the current call was connected. |
| Connected to | Dial string to which line is currently connected. |
| Dial string | Dial strings of logged calls (telephone numbers). On ISDN BRI interfaces, if you have specified a subaddress number in the dialer string or dialer map command, this number is included in the dial string after a colon. |
| Successes | Successful connections (even if no data is passed). |
| Failures | Failed connections; call not successfully completed. |
| Last called | Time that last call occurred to specific dial string. |
| Last status | Status of last call to specific dial string (successful or failed). |
| Default | If the DDR facility is using the dial string specified with the dialer string command, the word Default is appended to the Last status entry. |
If an interface is connected to a destination, a display is provided that indicates the idle time before the line is disconnected (decrements each second). Then the duration of the current connection is shown. The following shows an example of this display; it would appear after the third line in the show dialer display.
Time until disconnect 596 secs
Current call connected 0:00:25
After a call disconnects, the system displays the time remaining before being available to dial again. The following is an example of this display; it would appear after the third line in the show dialer display:
Time until interface enabled 8 secs
If the show dialer EXEC command is issued for an interface on which DDR is not enabled, the system displays an error message. The following is an example error message:
Async 1 - Dialing not enabled on this interface.
If an interface is configured for DDR, the show interfaces command now displays the following message:
Async1 is up, line protocol is up (spoofing)
Hardware is Async Serial
The spoofing indicates that the line really is not up, but the dialer is forcing the line to masquerade as "up" so that upper level protocols will continue to operate as expected. (Spoofing is a state added to allow DDR to work. Basically, the interface "dials on demand" in response to packets being routed to it. No packets are routed to down interfaces, so the router interface must pretend to be up [spoof] so packets will be routed to it when it's not connected. It's the normal idle state on a dial-on-demand interface.)
If caller ID screening is configured on a BRI is configured, the show dialer command display includes a line similar to the following:
1 incoming call(s) have been screened.
This line reports the number of calls that have been screened by the router.
To specify the password to be used in Challenge Handshake Authentication Protocol (CHAP) caller identification and Password Authentication Protocol (PAP), use the username command.
username name password secret| name | Host name, server name, user ID, or command name. |
| password | Possibly an encrypted password for this username. |
| secret | For CHAP authentication: specifies the secret for the local router or the remote device. The secret is encrypted when it is stored on the local router. This prevents the secret from being stolen. The secret can consist of any string of up to 11 printable ASCII characters. There is no limit to the number of username/password combinations that can be specified, allowing any number of remote devices to be authenticated. |
No password is predefined.
Global configuration
Add a name entry for each remote system that the local router requires authentication from.
The username command is required as part of the configuration for authentication protocols, such as CHAP and PAP. For each remote system that the local router communicates with from which it requires authentication, you add a username entry.
If there is no secret specified and debug serial-interface is enabled, an error is displayed when a link is established and the authentication protocol challenge is not implemented. Debugging information about authentication protocols is available using the debug serial-interface and debug serial-packet commands. See the Debug Command Reference publication for more information.
The following example configuration enables CHAP on interface serial 0. It also defines a password for the local server, Adam, and a remote server, Eve.
hostname Adam
interface serial 0
encapsulation ppp
ppp authentication chap
username Eve password theirsystem
When you look at your configuration file, the passwords will be encrypted and the display will look similar to the following:
hostname Adam
interface serial 0
encapsulation ppp
ppp authentication chap
username Eve password 7 121F0A18
hostname
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