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Table Of Contents
Supported Standards, MIBs, and RFCs
X.25 Failover Configuration Tasks
Configuring X.25 Failover on an Interface
Configuring X.25 Failover on an X.25 Profile
Monitoring and Maintaining X.25 Failover
X.25 Failover Configuration Example
X.25 Failover
This feature module describes the X.25 Failover feature and includes the following sections:
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Supported Standards, MIBs, and RFCs
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Feature Overview
Before the introduction of the X.25 Failover feature, multiple routes could be configured in an X.25 routing table to allow one or more secondary or backup interfaces to be used when a preferred (primary) interface is not usable. Routes would be examined in the order in which they appeared in the X.25 routing table. The first matching route was taken. However, since X.25 traffic is circuit-oriented, once a connection was established via the secondary interface, the connection remained active even after the primary interface returned to service. This situation is undesirable when the path via the secondary interface is slower or more expensive than the path via the primary interface.
The X.25 Failover feature enables you to configure that secondary interface to reset once the primary interface has come back up and remained operational for a specified amount of time, terminating any connections that are still using the secondary interface. Subsequent calls will be forwarded over the preferred interface.
You can configure the X.25 Failover feature on an X.25 interface or X.25 profile. The feature supports Annex G (X.25 over Frame Relay).
Benefits
The X.25 Failover feature helps ensure that calls are forwarded over the preferred interface whenever possible. If the preferred interface goes down, the secondary interface takes over. As soon as the preferred interface becomes operational again and remains so for a specified amount of time, the X.25 failover mechanism resets the secondary interface, causing the preferred interface to resume handling new calls.
Restrictions
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Related Documents
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Supported Platforms
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Supported Standards, MIBs, and RFCs
Standards
No new or modified standards are supported by this feature.
MIBs
No new or modified MIBs are supported are supported by this feature.
For descriptions of supported MIBs and how to use MIBs, see the Cisco MIB web site on Cisco Connection Online (CCO) at http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml.
RFCs
No new or modified RFCs are supported by this feature.
X.25 Failover Configuration Tasks
See the following sections for configuration tasks for the X.25 Failover feature. One of the following two tasks is required:
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The following task is optional:
Configuring X.25 Failover on an Interface
To configure X.25 failover on an interface, use the following commands beginning in global configuration mode:
Configuring X.25 Failover on an X.25 Profile
To configure X.25 failover on an X.25 profile, use the following commands beginning in global configuration mode:
Verifying X.25 Failover
To display information about the X.25 Failover feature, use the following EXEC command:
Monitoring and Maintaining X.25 Failover
To monitor the X.25 Failover feature, use the following EXEC command:
Configuration Examples
This section contains the X.25 failover configuration example.
X.25 Failover Configuration Example
In the following example, X.25 failover is configured on a network that is also configured for Annex G. If data-link connection identifier (DLCI) 13 or DLCI 14 on serial interface 1/0 goes down, dialer interface 1 will serve as the secondary interface. After DLCI 13 or 14 comes back up and remains up for 20 seconds, dialer interface 1 will reset, sending all calls back to the primary interface.
interface serial1/0encapsulation frame-relayframe-relay interface-dlci 13x25-profile frame1exitframe-relay interface-dlci 14x25-profile frame1exit!interface dialer1encapsulation x25exitx25 route ^1234 interface serial1/0 dlci 13x25 route ^1234 interface serial1/0 dlci 14x25 route ^1234 interface dialer1!x25 profile frame1 dtex25 fail-over 20 interface dialer1exit!Command Reference
This section documents new and modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.1 command reference publications.
x25 fail-over
To configure a secondary interface and set the number of seconds for which a primary interface must be up before the secondary interface resets, use the x25 fail-over command in the appropriate configuration mode. To prevent the secondary interface from resetting, use the no form of this command.
x25 fail-over seconds interface type number [dlci | mac-address]
no x25 fail-over seconds interface type number [dlci | mac-address]
Syntax Description
Defaults
No default behavior or values.
Command Modes
Interface configuration
X.25 profile configuration
Command History
Usage Guidelines
The x25 fail-over command can be configured on a primary X.25 interface or an X.25 profile only.
Examples
In the following example, X.25 failover is configured on a network that is also configured for Annex G. If data-link connection identifier (DLCI) 13 or DLCI 14 on serial interface 1/0 goes down, dialer interface 1 will serve as the secondary interface. After DLCI 13 or 14 comes back up and remains up for 20 seconds, dialer interface 1 will reset, sending all calls back to the primary interface.
interface serial1/0encapsulation frame-relayframe-relay interface-dlci 13x25-profile frame1exitframe-relay interface-dlci 14x25-profile frame1 dteexit!interface dialer1encapsulation x25exitx25 route ^1234 interface serial1/0 dlci 13x25 route ^1234 interface serial1/0 dlci 14x25 route ^1234 interface dialer1!x25 profile frame1x25 fail-over 20 interface dialer1exit!Related Commands
show x25 context
Displays information about X.25 links.
x25 profile
Configures an X.25 profile without specifying any hardware-specific information.
show x25 context
To view operating configuration status details of an X.25 link, use the show x25 context EXEC command.
show x25 context [interface number dlci number]
Syntax Description
interface number
(Optional) Specific logical X.25 virtual circuit interface.
dlci number
(Optional) Specific DLCI link.
Command Modes
EXEC
Command History
12.0(3)T
This command was introduced.
12.1(5)T
This command was modified to display information about X.25 Failover.
Examples
The following is sample output from the show x25 context command:
Router# show x25 contextSerial1 DLCI 20PROFILE DCE, address <none>, state R1, modulo 8, timer 0Defaults: idle VC timeout 0input/output window sizes 2/2, packet sizes 128/128Timers: T10 60, T11 180, T12 60, T13 60Channels: Incoming-only none, Two-way 1-1024, Outgoing-only noneRESTARTs 1/0 CALLs 0+0/0+0/0+0 DIAGs 0/0LAPB DCE, state CONNECT, modulo 8, k 7, N1 12056, N2 20T1 3000, T2 0, interface outage (partial T3) 0, T4 0VS 7, VR 6, tx NR 6, Remote VR 7, Retransmissions 0Queues: U/S frames 0, I frames 0, unack. 0, reTx 0IFRAMEs 111/118 RNRs 0/0 REJs 0/0 SABM/Es 14/1 FRMRs 0/0 DISCs 0/0The following is sample output from the show x25 context command when the X.25 Failover feature is configured. The "Fail-over delay" field appears when the primary interface has gone down and come back up again. The number of seconds indicates the time remaining until the secondary interface will reset.
Router# show x25 contextSerial1 DLCI 33PROFILE dxe/DCE, address 3032, state R1, modulo 8, timer 0Defaults:idle VC timeout 0input/output window sizes 2/2, packet sizes 128/128Timers:T20 180, T21 200, T22 180, T23 180Channels:Incoming-only none, Two-way 1-4095, Outgoing-only noneRESTARTs 12/0 CALLs 5+4/0+0/0+0 DIAGs 0/0Fail-over delay:16 seconds remaining on Dialer0LAPB dxe/DCE, state CONNECT, modulo 8, k 7, N1 12056, N2 20T1 3000, T2 0, interface outage (partial T3) 0, T4 0VS 1, VR 1, tx NR 1, Remote VR 1, Retransmissions 0Queues:U/S frames 0, I frames 0, unack. 0, reTx 0IFRAMEs 97/88 RNRs 0/0 REJs 0/0 SABM/Es 55490/12 FRMRs 186/0 DISCsTable 1 describes significant fields shown in the display.
Related Commands