Cisco IOS Wide-Area Networking Configuration Guide - Free Books

Configuring X.25 and LAPBConfiguring Additional X.25 Interface Parameters• Disabling PLP RestartsConfiguring X.25 FailoverMultiple routes can be configured in an X.25 routing table to allow one or more secondary or backupinterfaces to be used when a preferred (primary) interface is not usable. Routes are examined in the orderin which they appear in the X.25 routing table, and the first matching route is taken. However, since X.25traffic is circuit-oriented, once a connection is established via the secondary interface, the connectionremains active even after the primary interface returns to service. This situation is undesirable when thepath via the secondary interface is slower or more expensive than the path via the primary interface.X.25 Failover enables you to configure the secondary or backup interface to reset once the primaryinterface has come back up and remained operational for a specified amount of time, terminating anyconnections that are still using the secondary interface. Subsequent calls will then be forwarded over thepreferred interface.X.25 Failover supports Annex G (X.25 over Frame Relay), but it does not support XOT.You can configure X.25 Failover on an X.25 interface or X.25 profile.Configuring X.25 Failover on an InterfaceTo configure X.25 failover on an interface, use the following commands beginning in globalconfiguration mode:CommandPurposeStep 1 Router(config)# interface type number Configures an interface type and enters interfaceconfiguration mode.Step 2 Router(config-if)# encapsulation x25 Specifies the operation of a serial interface as anX.25 device.Step 3Router(config-if)# x25 fail-over seconds interfacetype number [dlci | MAC address]Specifies a secondary interface and sets the numberof seconds for which the primary interface must beup before the secondary interface resets.For an example X.25 failover configuration, see the section “X.25 Failover Example” later in thischapter.Configuring X.25 Failover on an X.25 ProfileTo configure X.25 failover on an X.25 profile, use the following commands beginning in globalconfiguration mode:CommandPurposeStep 1 Router(config)# x25 profile name {dce | dte | dxe} Configures an X.25 profile.Step 2Router(config-x25)# x25 fail-over seconds interfacetype number [dlci | MAC address]Specifies a secondary interface and sets the numberof seconds for which the primary interface must beup before the secondary interface resets.15