Cisco IOS Wide-Area Networking Configuration Guide - Free Books

Configuring X.25 and LAPBConfiguring Additional X.25 Routing FeaturesConfiguring Calling Address Interface-Based Insertion and RemovalThis feature describes a modification to the x25 route command that allows interface-based insertionand removal of the X.121 address in the X.25 routing table.This capability allows Cisco routers running X.25 to conform to the standard that specifies that X.25DCE devices should not provide the X.25 calling address, but instead that it should be inserted by theX.25 DTE based on interface. This calling address insertion and removal feature was designed for allrouters performing X.25 switching and requiring that an X.121 address be inserted or removed by theX.25 DTE based on the interface.This feature does not support XOT to X.25 routing using the input-interface keyword introduced by theCalling Address Insertion and Removal feature.To configure an input interface-based route statement into the X.121 address routing table, use either ofthe following commands beginning in global configuration command mode:CommandRouter(config)# x25 route input-interface interface sourcesource-pattern substitute-source rewrite-source [continue]orRouter(config)# x25 route input-interface interfacedispositionPurposeInserts an input interface-based route statement intothe routing table.Inserts simplest input interface-based statement intothe routing table.The continue keyword is optional. It performs address substitution without address forwarding. That is,it executes the address substitution instructions in each statement, but then stops short of actual callswitching, thereby postponing the actual switching process until a matching route statement with adisposition other than continue is reached. The continue keyword is most useful when you switch callsamong four or more routes. If your network has three or fewer routes, the continue keyword will notsave any steps.For examples of configuring interface-based call address insertion and removal, see the sections“Inserting and Removing X.121 Addresses As Calls Are Routed Example” and “Forwarding Calls Usingthe continue Keyword Example” later in this chapter.Verifying Interface-Based Calling Address InsertionTo display the routes assigned by the x25 route command, use the show x25 route command in EXECmode. A sample display follows.Router# show x25 route# Match Substitute Route to1 dest ^01 input-int Serial0 Sub-dest \1 Sub-source 00\0 Serial1Substituting Addresses in an X.25 RouteWhen interconnecting two separate X.25 networks, you must sometimes provide address substitution forroutes. The x25 route command supports modification of X.25 source and destination addresses.To modify addresses, use either or both of the following commands in global configuration mode:37