Cisco IOS Wide-Area Networking Configuration Guide - Free Books

Configuring X.25 over Frame Relay (Annex G)Configuring X.25 and LAPBCommandRouter(config)# x25 route x121address xot dnspatternPurposeConfigures XOT routing to search for IP addresses in DNS.For an example of configuring DNS-based X.25 routing, see the section “DNS-Based X.25 RoutingExample” later in this chapter.Verifying DNS-Based X.25 RoutingTo verify that the DNS-Based X.25 Routing feature is configured, use the show x25 route command inEXEC mode:Router# show x25 route# Match Substitute Route to1 dest 444 xot dns \02 dest 555 xot dns \0If DNS-based X.25 routing is not functioning correctly, check that your DNS is configured properly andoperating correctly as follows:• Use the show hosts command to display temporary entries cached by DNS at the router.• Use debug x25 events and debug domain commands to display current data flow. See the Cisco IOSDebug Command Reference for more information.Verifying DNS-Based X.25 Mnemonic ResolutionTo verify DNS-based X.25 mnemonic resolution, use the show hosts command in EXEC mode. Allpermanent (perm) entries of type X.121 should be removed from the route table for DNS-based X.25routing to work.In the following example, the mnemonic “destination_host” is showing itself to be a permanent entry:Router# show hostsDefault domain is home.comName/address lookup uses domain serviceName servers are 10.1.1.40Host Flags Age Type Address(es)destination_host (perm, OK) 1 X.121 222Configuring X.25 over Frame Relay (Annex G)Annex G (X.25 over Frame Relay) facilitates the migration of traffic from an X.25 backbone to a FrameRelay backbone by permitting encapsulation of X.25 traffic within a Frame Relay connection. WithAnnex G, transporting X.25 over Frame Relay has been simplified by allowing direct and transparentX.25 encapsulation over a Frame Relay network. Annex G is supported only on Frame Relay maininterfaces (not subinterfaces) and over Frame Relay PVCs. However, X.25 PVC connections are notsupported, but only X.25 SVC connections.42