Table Of Contents

Dial-on-Demand Routing Commands

backup delay

backup interface

backup load

chat-script

clear snapshot quiet-time

dialer callback-secure

dialer callback-server

dialer caller

dialer dtr

dialer enable-timeout

dialer fast-idle

dialer group

dialer hold-queue

dialer idle-timeout

dialer in-band

dialer-list list

dialer-list protocol

dialer load-threshold

dialer map

dialer map snapshot

dialer priority

dialer rotary-group

dialer string

dialer wait-for-carrier-time

encapsulation ppp

interface dialer

map-class

ppp callback

script dialer

show dialer

show snapshot

snapshot client

snapshot server

username

Dial-on-Demand Routing Commands

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This chapter lists dial backup and dial-on-demand routing (DDR) commands, explains command syntax, and provides usage guidelines.

Dial backup provides protection against wide-area network (WAN) downtime by allowing you to configure a backup serial line circuit-switched connection.

DDR provides network connections across the Public Switched Telephone Network (PSTN). Traditionally, networks have been interconnected using dedicated lines for WAN connections. With DDR, you can use modems to establish low-volume, periodic network connections over public circuit-switched networks.

For information about configuring DDR and configuration examples, refer to the "Configuring Dial-on-Demand Routing" chapter in the Access and Communication Servers Configuration Guide.

backup delay

Use the backup delay interface configuration command to define how much time should elapse before a secondary line status changes after a primary line status has changed. Use the no form of the command to return to the default, which means as soon as the primary fails, the secondary is immediately brought up without delay.

backup delay {enable-delay | never} {disable-delay | never}
no backup delay {enable-delay | never} {disable-delay | never}

Syntax Description

enable-delay	Number of seconds that elapse after the primary line goes down before the access server activates the secondary line.
disable-delay	Number of seconds that elapse after the primary line goes up before the access server deactivates the secondary line.
never	Prevents the secondary line from being activated or deactivated.

Default

0 seconds

Command Mode

Interface configuration

Usage Guidelines

For environments in which 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 line.

Example

The following example sets a 10-second delay on deactivating the secondary line (serial interface 0) however, the line is activated immediately.

interface serial 0

backup delay 0 10

backup interface

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

backup interface number
no backup interface number

Syntax Description

number

Interface number.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

The interface you define with this command can only back up one interface.

Example

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

interface async 0

backup interface serial 1

backup load

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

backup load {enable-threshold | never} {disable-load | never}
no backup load {enable-threshold | never} {disable-load | never}

Syntax Description

enable-threshold	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 sue to traffic load.

Default

No traffic load threshold is set for dial backup.

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.

The secondary line is disabled when one of the following conditions occur:

•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.

•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.

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.

Example

The following example sets the traffic load threshold to 60 percent of the primary line for serial interface 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

chat-script

Use the chat-script global configuration command to create a script that will place a call over a modem. Use the no form of this command to disable the specified chat script.

chat-script script-name expect-send
no chat-script script-name

Syntax Description

script-name	Name of the chat script.
expect-send	Content of the chat script.

Default

No chat scripts are configured.

Command Mode

Global configuration

Usage Guidelines

Chat scripts are used in dial-on-demand routing to give commands to dial a modem and commands to log onto remote systems. The defined script will be used to place a call over a modem.

Some characteristics of chat scripts are as follows:

•Chat scripts are case sensitive.

•You can have any number of ABORT sequences active at once.

•When a chat script starts, the default timeout is 5 seconds. Changes to the timeout persist until the next time you change them in the script.

•A string within quotation marks (" ") is treated as a single entity.

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.

Suggested Chat Script Naming Conventions

A suggested chat script naming convention is as follows:

vendor-type-modulation

In other words, the syntax of the chat-script command becomes the following:

 chat-script vendor-type-modulation expect-send...

For 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:

•telebit-tb-b103

•telebit-tb-v21

•telebit-tb-v22

•codex-326x-b103

•codex-326x-v21

•codex-326x-v22

•codex-326x-v22bis

•codex-326x-v32

•codex-326x-v32bis

•usr-courier-v22bis

•usr-courier-hst

•usr-courier-v32

•usr-courier-v32bis

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.

Escape Sequences

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 .

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 7-1.

Table 7-1

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 two 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.

Chat Script Escape Sequences

Expect-Send Pairs

Sample supported expect-send pairs are described in .

Table 7-2 Sample Supported Expect-Send Pairs

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.

Alternate Handlers

ABORT sink instead of ABORT ERROR means that the system will abort when it sees sink instead of when it sees ERROR.

Missed Characters

After the connection is established and return is entered, 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 period.

Example

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

Related Commands

dialer map
script dialer

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 within 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

dialer callback-secure

To enable callback security, use the dialer callback-secure interface configuration command.

dialer callback-secure

Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command ensures that the initial call is always disconnected at the receiving end and the return call is made only if the username is configured for callback. If the username (hostname in the dialer map command) is not configured for callback, the initial call stays up and no return call is made.

Related Commands

dialer callback-server
dialer map
map-class
ppp callback accept

dialer callback-server

To enable an interface to make return calls when callback is successfully negotiated, use the dialer-callback server interface configuration command.

dialer callback-server [username] [dialstring]

Syntax Description

username	Identify the return call's dialstring by looking up the authenticated hostname in a dialer map command. This is the default.
dialstring	Identify the return call's dialstring during callback negotiation.

Default

Disabled. The default keyword is username.

Command Mode

Interface configuration

Related Commands

dialer callback-secure
dialer enable-timeout
dialer hold-queue
dialer map
map-class
ppp callback

dialer caller

To configure caller ID screening, use the dialer caller interface configuration command. To disable this feature, use the no form of this command.

dialer caller number
no dialer caller number

Syntax Description

number

Telephone number for which to screen. Specify an x to represent a single "don't-care" character. The maximum length of each number is 25 characters.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command configures the access server to accept calls from the specified number.

The maximum length of each number is 25 characters.

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Note   Caller ID screening requires a local switch that is capable of delivering the caller ID to the access server. If you enable caller ID screening but do not have such a switch, no calls will be allowed in.

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Examples

The following example configures the access server to accept a call with a delivered caller ID equal to 4155551234:

dialer caller 4155551234

The following example configures the access server to accept a call with a delivered caller ID having 41555512 and any numbers in the last two positions:

dialer caller 41555512xx

Related Command

show dialer

dialer dtr

To enable DDR on an interface and specify that the serial line is connected by non-V.25bis modems using EIA signaling only (the data terminal ready [DTR] signal), use the dialer dtr interface configuration command. To disable dial-on-demand routing for the interface, use the no form of this command.

dialer dtr
no dialer dtr

Syntax Description

This command has no keywords or arguments.

Default

This command has no default values.

Command Mode

Interface configuration

Usage Guidelines

A serial interface configured for DTR dialing can place calls only; it cannot accept them.

When an interface is configured for DTR dialing, the remote interface can be configured for in-band dialing or not configured for anything but encapsulation, depending on the desired behavior. If the remote interface is expected to terminate a call when no traffic is transmitted for some time, it must be configured for in-band dialing (along with access lists and a dummy dialer string). If the remote interface is purely passive, no configuration is necessary.

Hunt group leaders cannot be configured for DTR dialing.

The dialer map and dialer string commands have no effect on DTR dialers.

Example

The following example enables DDR and specifies DTR dialing on an interface:

dialer dtr

Related Commands

dialer in-band
dialer map
dialer string

dialer enable-timeout

Use the dialer enable-timeout interface configuration command 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 no form of the command to reset the enable timeout value to the default.

dialer enable-timeout seconds
no dialer enable-timeout

Syntax Description

seconds

Number of seconds that the access server waits before the next call can occur on the specific interface. Acceptable values are positive, nonzero integers. This value must be greater than the serial pulse interval for this interface, set via the pulse-time command.

Default

15 seconds

Command Mode

Interface configuration

Usage Guidelines

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.

Example

The following example specifies a waiting period of 30 seconds on async interface 1:

interface async 1

dialer enable-timeout 30

dialer fast-idle

Use the dialer fast-idle interface configuration command 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 no form of the command to reset the timeout period to the default.

dialer fast-idle seconds
no dialer fast-idle

Syntax Description

seconds

Idle time, in seconds, that must occur on an interface before the line is disconnected. Acceptable values are positive, nonzero integers.

Default

20 seconds

Command Mode

Interface configuration

Usage Guidelines

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 the 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.

Example

The following example specifies a fast idle timeout of 35 seconds on async interface 1:

interface async 1

dialer fast-idle 35

Related Commands

dialer idle-timeout
dialer map

dialer group

Use the dialer-group interface configuration command to control access. You must specify the number of a dialer access group to which a specific interface is assigned. Use the no form of the command to remove an interface from the specified dialer access group.

dialer-group group-number
no dialer-group

Syntax Description

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.

Default

No dialer access group is specified.

Command Mode

Interface configuration

Usage Guidelines

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.

Example

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

access-list 101 deny igrp 0.0.0.0 255.255.255.255 255.255.255.255 0.0.0.0 

access-list 101 permit ip 0.0.0.0 255.255.255.255 0.0.0.0 255.255.255.255 

dialer-list 1 list 101

Related Command

dialer-list

dialer hold-queue

To allow "interesting" outgoing packets to be queued until a modem connection is established and to specify a timeout period for PPP callback connections to be established, use the dialer hold-queue interface configuration command. To disable the hold queue, use the no form of this command.

dialer hold-queue packets timeout seconds

Syntax Description

packets	Number of packets, in the range 0 to 100 packets, to hold in the queue. This argument is optional with the no form of the command.
seconds	The value of seconds plus the dialer enable timeout equals the number of seconds that packets are to be held for a callback connection to be established.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

A dialer hold queue can be configured on any type of dialer, including in-band synchronous, asynchronous, Data Terminal Ready (DTR), and ISDN dialers. Rotary groups can be configured with a dialer hold queue. If a rotary group is configured with a hold queue, all members of the group will be configured with a dialer hold queue and no individual member's hold queue can be altered.

If no hold queue is configured, packets are dropped during the time required to establish a connection.

If no callback connection is established within the timeout period, the packets are discarded.

Related Commands

dialer callback-secure
dialer map
map-class
ppp callback

dialer idle-timeout

Use the dialer idle-timeout interface configuration command to specify the idle time before the line is disconnected. Use the no form of the command to reset the idle timeout to the default.

dialer idle-timeout seconds
no dialer idle-timeout

Syntax Description

seconds

Idle time, in seconds, that must occur on an interface before the line is disconnected. Acceptable values are positive, nonzero integers.

Default

120 seconds

Command Mode

Interface configuration

Usage Guidelines

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.

Example

The following example specifies of an idle timeout of 3 minutes (180 seconds) on async interface 1:

interface async 1

dialer idle-timeout 180

Related Command

dialer fast-idle

dialer in-band

Use the dialer in-band interface configuration command to specify that DDR is to be supported. The dialer in-band command specifies that chat scripts will be used on asynchronous interfaces and V.25bis will be used on synchronous interfaces. Use the no form of the command to disable dial-on-demand routing for the interface.

dialer in-band [no-parity | odd-parity]
no dialer in-band

Syntax Description

no-parity	(Optional) No parity is applied to the dialer string that is sent out to the modem on synchronous interfaces.
odd-parity	(Optional) Dialed number will have odd parity (7-bit ASCII characters with the eighth bit the parity bit) on synchronous interfaces.

Default

Disabled. No parity is applied to the dialer string.

Command Mode

Interface configuration

Usage Guidelines

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 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.

Example

The following example specifies DDR for async interface 1:

interface async 1

dialer in-band

Related Commands

dialer map
dialer string

dialer-list list

Use the dialer-list list global configuration command to group access lists. This command applies access lists to dialer access groups to control automatic dialing using DDR with standard IP access lists. Use the no form of the global configuration command to disable automatic dialing.

dialer-list dialer-group list access-list-number
no dialer-list dialer-group list access-list-number

Syntax Description

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 and service access point (SAP) access lists. See for the supported access list types and numbers.

Table 7-3

Access List Type	Access List Number Range
Standard IP	1-99
Extended IP	100-199
Standard Novell IPX	800-899
Extended Novell IPX	900-999
Novell SAP	1000-1099

Supported Access List Types and Numbers

Default

Disabled

Command Mode

Global configuration

Usage Guidelines

This command applies access lists to dialer access groups defined with the dialer-group command. See the Access and Communication Servers Configuration Guide for more information about configuring IP access lists.

Examples

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

Related Command

dialer group

dialer-list protocol

To define a DDR dialer list to control dialing by protocol or by a combination of protocol and access list, use the dialer-list protocol global configuration command. To delete a dialer list, use the no form of this command.

dialer-list dialer-group protocol protocol-name {permit | deny | list access-list-number}
no dialer-list dialer-group [protocol protocol-name [list access-list-number]]

Syntax Description

dialer-group	Number of a dialer access group identified in any dialer group interface configuration command.
protocol-name	One of the following protocol keywords: appletalk, ip, or ipx.
permit	(Optional) Permits access to an entire protocol.
deny	(Optional) Denies access to an entire protocol.
list	Specifies that an access list will be used for defining a granularity finer than an entire protocol.
access-list-number	Access list number. Access list numbers include any IP or Novell IPX standard or extended access lists, Novell IPX extended and Service Access Point (SAP) access lists. See the "" table in the "Usage Guidelines" section for the supported access list types and numbers.

Default

No dialer lists are defined.

Command Mode

Global configuration

Usage Guidelines

The various no forms of this command have the following effects:

•The no dialer-list 1 command deletes all lists configured with list 1, regardless of the keyword previously used (permit, deny, protocol, or list).

•The no dialer-list 1 protocol protocol-name command deletes all lists configured with list 1 and protocol protocol-name.

•The no dialer-list 1 protocol protocol-name list access-list-number command deletes the specified list.

The dialer-list protocol form of this command permits or denies access to an entire protocol. The dialer-list protocol list form of this command provides a finer permission granularity and also supports protocols that were not previously supported.

The dialer-list protocol list form of this command applies protocol access lists to dialer access groups to control dialing using DDR. The dialer access groups are defined with the dialer-group command. See the Access and Communication Servers Configuration Guide for more information about configuring access lists for protocols.

Although the dialer-list list command is still supported for IP, IPX, and AppleTalk, the new dialer-list protocol list form of this command should be used for all protocols.

lists the access list types and numbers that the dialer-list protocol list command supports.

Table 7-4

Access List Type	Access List Number Range (decimal)
AppleTalk	600-699
IP (standard)	1-99
IP (extended)	100-199
Novell IPX (standard)	800-899
Novell IPX (extended)	900-999

Dialer-List Supported Access List Types and Numbers

Examples

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 example 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 protocol ip list 101

Then the following command would be used to place list 301 into dialer access group 1:

dialer-list 1 protocol decnet list 301

In the following example, an IP access lists is defined. The IP access lists define IGRP packets as uninteresting, but permits other IP packets to trigger calls.

access-list 101 deny igrp 0.0.0.0 255.255.255.255 0.0.0.0 255.255.255.255

access-list 101 permit ip 0.0.0.0 255.255.255.255 0.0.0.0 255.255.255.255

Then the following two commands place the IP access list into dialer access group 1:

dialer-list 1 protocol ip list 101

Related Commands

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

access-list †
dialer group
dialer-list list

dialer load-threshold

To configure bandwidth on demand by setting the maximum load before the dialer places another call to a destination or brings up another interface, use the dialer load-threshold interface command. To disable the setting, use the no form of this command.

dialer load-threshold load [either | outbound | inbound]
no dialer load-threshold

Syntax Description

load	Interface load beyond which the dialer will initiate another call to the destination. This argument is a number between 1 and 255.
either | outbound | inbound	(Optional) Determine the threshold on the maximum outbound or inbound traffic, outbound traffic only, or inbound traffic only. The default is outbound.

Default

No maximum load is predefined. The default threshold determination is outbound.

Command Mode

Interface configuration

Usage Guidelines

This command applies to dialer rotary groups only.

The dialer will initiate another call to the destination 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 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.

If the interface is configured for multilink PPP and the threshold is set to 1, all available members of a rotary group are connected to the same destination. After the initial link is connected, it stays connected; DDR does not disconnect it. To disconnect, either clear the interface or shut it down.

See the "Interface Commands" chapter for a full description of the bandwidth command.

Example

In the following example, if the load to a particular destination on an interface dialer rotary group 5 exceeds interface load 200 outbound , the dialer will initiate another call to the destination. If used with multilink PPP, another interface in the same dialer rotary group will be brought up when the load exceeds the outbound threshold:

interface dialer 5 
dialer load-threshold 200

Related Commands

bandwidth
dialer rotary-group
interface dialer
ppp multilink

dialer map

To configure any non-DTR dialer interface as a PPP callback server, use the following form of the dialer map interface configuration command. To remove a prior dialer map class configuration, use the no form of the command.

dialer map protocol next-hop-address name hostname class classname dial-string
no dialer map protocol next-hop-address name hostname class classname dial-string

Syntax Description

protocol	Protocol keyword. See for a list of supported protocols and their keywords.
next-hop-address	Protocol address used to match against addresses to which packets are destined. This argument is not used with the bridge protocol keyword.
name	(Optional) Indicates the remote system with which the local router communicates.
hostname	(Optional) Case-sensitive name or ID of the remote device (usually the host name). (The PPP callback feature does not support the use of ISDN calling line identification (caller ID) in the hostname argument.)
class classname	Name of the class created by the map-class command for this PPP callback client and server.
dial-string	(Optional) Telephone number sent to the dialing device when it recognizes packets with the specified next-hop-address that matches the access lists defined. The dial string must be the last item in the command line.

Default

No dialer map is defined; no default values are defined.

Command Mode

Interface configuration

Usage Guidelines

The classname is defined by the map-class dialer command. This form of the dialer map command identifies a specific host as configured for PPP callback. If the dialer callback-server command uses the username keyword, this dialer map entry is consulted to determine the dialstring for callback.

The hostname identified in the dialer map command and the username identified in the username password command must be identical. Both commands are case sensitive.

Table 7-5 Dialer Map Command Supported Protocols

Keyword	Protocol
appletalk	AppleTalk
bridge	Bridging
clns	ISO CLNS
decnet	DECnet
ip	IP
ipx	Novell IPX
novell	Novell IPX
snapshot	Snapshot Routing
vines	Banyan VINES
xns	Xerox Network Services

Related Commands

dialer callback-secure
dialer callback-server
dialer enable-timeout
map-class
ppp callback
username password

dialer map snapshot

To define a dialer map for Cisco's snapshot routing protocol on a client router connected to a DDR interface, use the dialer map snapshot interface configuration command. To delete one or more previously defined snapshot routing dialer maps, use the no form of this command.

dialer map snapshot sequence-number dial-string
no dialer map snapshot [sequence-number]

Syntax Description

sequence-number	An number in the range from 1 to 254, inclusive, that uniquely identifies a dialer map.
dial-string	Telephone number of the remote host.

Default

No snapshot routing dialer map is defined.

Command Mode

Interface configuration

Usage Guidelines 

Use the no dialer map snapshot form of this command to remove all previously defined snapshot dialer maps on the client router; use the no dialer map snapshot sequence-number form of this command to delete a specified dialer map.

Example

The following examples define snapshot dialer maps on a client router:

dialer map snapshot 12 4151231234

dialer map snapshot 13 4151231245

The following example removes one of the previously defined snapshot routing dialer maps on the client router:

no dialer map snapshot 13

Related Commands

dialer rotary-group
interface dialer
snapshot client

dialer priority

To set the priority of an interface in a dialer rotary group, use the dialer priority interface configuration command. Use the no form of this command to revert to the default setting.

dialer priority number
no dialer priority

Syntax Description

number

Specifies the priority of an interface in a dialer rotary group; the lowest number indicates the highest priority. A number from 0 to 255. The default is 0.

Default

No priority is predefined. When priority is defined, the default value is 0.

Command Mode

Interface configuration

Usage Guidelines

The value 0 indicates the lowest priority and 255 indicates the highest priority. The dialer priority command controls which interfaces within a dialer rotary group will be used first. Higher priority interfaces (configured with higher number value) are used first. This command is only meaningful for interfaces that are part of dialer rotary groups.

The priority command gives the administrator the ability to tell the dialer rotary group which free interface (and by extension which modem) to use first. This command applies to outgoing calls only.

Examples

In the following example, async interface 3 will be used after interfaces with higher priority and before interfaces with lower priority.

interface async 3 
dialer priority 5

For example, a Cisco 2511 has a selection of 14400 modems on it. Some of them are perceived to be better performers than others. You also have two 4800-bps, three 1200-bps, and one 300-bps modem. They are all on interfaces that are in a dialer rotary group. You do not want the 2511 to make the call on the 300-baud modem if any of the faster modems are free. You want the 2511 to use the highest-performance modems first, and the slowest modems last.

Related Commands

dialer rotary-group
interface dialer

dialer rotary-group

Use the dialer rotary-group interface configuration command to include an interface in a dialer rotary group.

dialer rotary-group number

Syntax Description

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.

Default

No dialer rotary groups are defined.

Command Mode

Interface configuration

Example

The following example places async interfaces 1 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 172.30.2.1 255.255.255.0

ip address 172.30.4.1 255.255.255.0 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 172.30.2.5 name YYY 14155553434

dialer map ip 172.30.4.5 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

Related Command

interface dialer

dialer string

Use the dialer string interface configuration command to specify the string (telephone number) to be called for interfaces calling a single site. Use the no dialer string command to delete the dialer string specified for the interface.

dialer string dial-string
no dialer string

Syntax Description

dial-string

String of characters to be sent to a DCE.

Default

No dialer strings are defined by default.

Command Mode

Interface configuration

Usage Guidelines

To use this command on an asynchronous interface, a modem chat script must be defined for the associated line by using the script dialer 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.

---

Note   If a dialer string command is specified without a dialer-group command with access lists defined, dialing never will be initiated. If debug dialer is enabled, an error message will be displayed indicating that dialing never will occur.

---

The string of characters specified for the dial-string argument is the default number used under the following conditions:

•A dialer map command is not included in the interface configuration.

•The next-hop-address specified in a packet is not included in any of the dialer map interface configuration commands recorded—assuming that the destination address passes any access lists specified for DDR with the dialer-list command.

ITU-T V.25bis Options

On synchronous interfaces, depending on the type of modem you are using, ITU-T V.25 bis options might be supported as dial-string parameters of the dialer string command. Supported options are listed in . 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.

---

Note   The ITU-T carries out the functions of the former Consultative Committee for International Telegraph and Telephone (CCITT).

---

Table 7-6 CCITT V.25bis 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.

Example

The following example specifies a DDR telephone number to be tone dialed on async interface 1 using the dialer string command:

interface async 1

dialer string T14085553434

Related Commands

dialer group
dialer in-band
dialer map
show dialer

dialer wait-for-carrier-time

Use the dialer wait-for-carrier-time interface configuration command to specify how long to wait for a carrier. On asynchronous interfaces, this command sets the total time allowed for the chat script to run. Use the no form of the command to reset the carrier wait time value to the default.

dialer wait-for-carrier-time seconds
no dialer wait-for-carrier-time

Syntax Description

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. The default is 30 seconds.

Default

30 seconds

Command Mode

Interface configuration

Usage Guidelines

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).

Example

The following example specifies a carrier wait time of 45 seconds on async interface 1:

interface async 1

dialer wait-for-carrier-time 45

Related Command

dialer enable-timeout

encapsulation ppp

Use the encapsulation ppp interface configuration command to configure Point-to-Point Protocol (PPP) encapsulation.

encapsulation ppp

Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

The Point-to-Point Protocol (PPP), described in RFCs 1331 and 1332, is designed to encapsulate Internet Protocol (IP) and IPX datagrams and other network layer protocol information over point-to-point links.

The current implementation of PPP supports no configuration options. The software sends no options, and any proposed options are rejected.

Of the possible upper-layer protocols, only IP is supported at this time. Thus, the only upper-level protocol that can be sent or received over a point-to-point link using PPP encapsulation is IP. Refer to RFC 1134 for definitions of the codes and protocol states.

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.

Example

The following example enables PPP encapsulation on async interface 1.

interface async 1

encapsulation ppp

Related Commands

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

keepalive †
ppp authentication chap †

interface dialer

Use the interface dialer global configuration command to define a dialer rotary group.

interface dialer number

Syntax Description

number

Number of the dialer rotary group. It can be number in the range 0 through 255.

Default

No dialer rotary groups are defined.

Command Mode

Global configuration

Usage Guidelines

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 c