Back-to-Back Frame Relay - External Link Back-to-Back Frame Relay Contents Introduction Hardware and Software Versions Network Diagram Configurations Command Summary show Commands Related Information Introduction This document is a sample configuration for setting up two Cisco routers back-to-back using Frame Relay (FR) encapsulation. The routers are connected using data communications equipment (DCE) and a data terminal equipment (DTE) serial cable. Back-to-back setups are useful in test environments. The simplest and preferred method for configuring back-to-back setups is described in this document. A FR switch or DCE device is used between FR routers to provide Local Management Interface (LMI) status messages. Because there is no switch in a back-to-back scenario, LMI processing is disabled on both routers. You also can configure a back-to-back setup with one router providing LMI status updates for the other. However, such a configuration is necessary only if the LMI debugging messages are to be checked in a back-to-back setup. In this case, LMI processing is not disabled and one side functions as a hybrid FR switch by responding to LMI status enq. For more details on this configuration, please see "Back-to-Back Frame Relay Hybrid Switching." In the sample configuration, the router connected to the DCE cable must provide clocking. Router1 provides the clock at 64 kbps (clock rate 64000). http://www.cisco.com/warp/public/125/frbacktoback.html (1 of 5) [4/19/2001 9:01:08 PM] Back-to-Back Frame Relay - External Link Hardware and Software Versions To implement this configuration, you need the following hardware and software components: ● Cisco IOS® Software Release 10.0 and later that supports FR encapsulation. ● Two routers, each with an interface that supports FR encapsulation. Note: The information in this document was taken from an isolated lab environment. Make sure you understand the potential impact of a command on your network before you use it. This configuration was developed and tested using the software and hardware versions below. ● Cisco IOS Software Release 12.1(2). ● Cisco 1604 routers. Network Diagram Configurations Router 1 Router 2 http://www.cisco.com/warp/public/125/frbacktoback.html (2 of 5) [4/19/2001 9:01:08 PM] Back-to-Back Frame Relay - External Link ! interface Serial0 no ip address encapsulation frame-relay no keepalive !--- This command disables LMI !--- processing. clock rate 64000 ! interface Serial0.1 point-to- point !--- A point-to-point subinterface has !--- been created. ip address 172.16.120.105 255.255.255.0 frame-relay interface-dlci 101 !--- DLCI 101 has been assigned to this !--- interface ! ! interface Serial0 no ip address encapsulation frame-relay no keepalive !--- This command disables LMI !--- processing. ! interface Serial0.1 point-to- point !--- A point-to-point subinterface has !--- been created. ip address 172.16.120.120 255.255.255.0 frame-relay interface-dlci 101 !--- DLCI 101 has been assigned to this !--- interface ! Command Summary The above configuration disables LMI processing on both routers when the no keepalive command is issued. Because LMI messages are not exchanged, interfaces remain up/up unless clocking is lost on the DTE cable side or data terminal ready (DTR), and Request To Send (RTS) is lost on the DCE cable side. FR map statements are not required because point-to-point subinterfaces have been configured. The data- link collection identifiers (DLCIs) specified with the frame-relay interface-dlci command must match. When a DLCI is assigned to a subinterface, a frame map is created for the subinterface. ● no keepalive - disables the LMI mechanism for serial lines using FR encapsulation. ● frame-relay interface-dlci - assigns a DLCI to a specified FR subinterface. FR map statements can be configured on the main interface if point-to-point subinterfaces are not desired. As long as FR map statements are correct and have matching DLCIs configured, connectivity will be maintained. http://www.cisco.com/warp/public/125/frbacktoback.html (3 of 5) [4/19/2001 9:01:08 PM] Back-to-Back Frame Relay - External Link show Commands ● show frame-relay map - displays map entries and information about connections. ● show frame-relay pvc - displays statistics about permanent virtual circuits (PVCs) for FR interfaces. When a FR map statement is properly configured, the output from a show frame-relay map command should resemble the output below obtained from Router1. Router1#show frame map Serial0.1 (up): point-to-point dlci, dlci 101(0x65,0x1850), broadcast Router1# Because LMI processing has been disabled, the router cannot determine the status of PVCs from LMI status messages. PVCs can only be statically defined. Router1#show frame pvc PVC Statistics for interface Serial0 (Frame Relay DTE) DLCI = 101, DLCI USAGE = LOCAL, PVC STATUS = STATIC, INTERFACE = Serial0.1 input pkts 98 output pkts 52 in bytes 25879 out bytes 12160 dropped pkts 0 in FECN pkts 0 in BECN pkts 0 out FECN pkts 0 out BECN pkts 0 in DE pkts 0 out DE pkts 0 out bcast pkts 37 out bcast bytes 10600 PVC create time 00:57:07, last time PVC status changed 00:46:13 Related Information ● More Cisco WAN Technical Features http://www.cisco.com/warp/public/125/frbacktoback.html (4 of 5) [4/19/2001 9:01:08 PM] Back-to-Back Frame Relay - External Link All contents are Copyright © 1992--2001 Cisco Systems Inc. All rights reserved. Important Notices and Privacy Statement. http://www.cisco.com/warp/public/125/frbacktoback.html (5 of 5) [4/19/2001 9:01:08 PM] Back-to-Back Frame Relay Hybrid Switching - External Link Back-to-Back Frame Relay Hybrid Switching Contents Introduction Hardware and Software Versions Network Diagram Configurations Command Summary debug and show Commands Sample Debug Output Related Information Introduction This document provides configuration information for Cisco routers connected back-to-back using Frame Relay (FR) encapsulation with the Local Management Interface (LMI) enabled. The routers are connected using data communication equipment (DCE) and a data terminal equipment (DTE) serial cable. One of the routers is configured to serve as a hybrid FR switch to respond to LMI status enq sent by the second router. The router connected to the DCE cable must provide clocking. In this configuration, Router1 provides the clock at 64 kbps (clock rate 64000). Back-to-back setup is useful in test environments. Such a configuration is necessary only if the LMI debug messages are to be checked. For information on the most common method used to configure routers back-to-back with FR encapsulation, please refer to "Back-to-Back Frame Relay." Hardware and Software Versions http://www.cisco.com/warp/public/125/frbacktoback_hybrid.html (1 of 6) [4/19/2001 9:01:11 PM] Back-to-Back Frame Relay Hybrid Switching - External Link To implement this configuration, the following hardware and software components are required: ● Cisco IOS® Software Release 10.0 or later that supports FR encapsulation. ● A router with an interface that supports FR encapsulation. Note: Information in this document was taken from an isolated lab environment. Make sure you understand the potential impact of a command on your network before you use it. This configuration was developed and tested using the software and hardware versions below. ● Cisco IOS Software Release 12.1(2). ● Cisco 1604 routers. Network Diagram Configurations Router 1 Router 2 frame-relay switching !--- Allows this router to function !--- as a FR switch. ! interface Serial0 ip address 172.16.120.105 255.255.255.0 encapsulation frame-relay frame-relay map ip 172.16.120.120 101 broadcast !--- The data-link connection identifiers(DLCIs) ! Interface Serial0 ip address 172.16.120.120 255.255.255.0 encapsulation frame-relay frame-relay map ip 172.16.120.105 101 broadcast !--- The DLCIs configured in the map !--- statements must match. ! http://www.cisco.com/warp/public/125/frbacktoback_hybrid.html (2 of 6) [4/19/2001 9:01:11 PM] Back-to-Back Frame Relay Hybrid Switching - External Link !--- configured in the map statements must match. clock rate 64000 frame-relay intf-type dce !--- This command specifies the !--- interface to handle LMI like a !--- FR DCE device. ! Command Summary Router1 is configured to function as a hybrid FR switch and respond to LMI enquires sent by Router 2. The global command frame-relay switching enables permanent virtual circuit (PVC) switching on Router1. The interface command frame-relay intf-type dce enables Router1 to function as a switch connected to a router. The no keepalive command has not been added to either router. No special configuration is needed for Router2. For more information on configuring a router as a hybrid DTE/DCE FR switch, please see the configuration example in "Hybrid Frame Relay Switching." ● frame-relay switching - enables PVC switching on a FR DCE device or a network-to-network interface. ● frame-relay intf-type dce - configures the FR switch type. A router or an access server functions as a switch connected to a router. debug and show Commands ● show frame-relay pvc - displays information and statistics about PVCs for FR interfaces. ● show frame-relay lmi - displays statistics about the LMI. ● debug frame-relay lmi - displays information about the LMI packets exchanged between routers. Before attempting any debug commands, please refer to Important Information on Debug Commands. Sample Debug Output The show frame-relay pvc command used for Router1 provides the status of PVCs and confirms that map statements are configured properly. Router1 acts as a FR DCE device (FR switch). http://www.cisco.com/warp/public/125/frbacktoback_hybrid.html (3 of 6) [4/19/2001 9:01:11 PM] Back-to-Back Frame Relay Hybrid Switching - External Link Router1#show frame-relay pvc PVC Statistics for interface Serial0 (Frame Relay DCE) Active Inactive Deleted Static Local 1 0 0 0 Switched 0 0 0 0 Unused 0 0 0 0 DLCI = 101, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0 input pkts 207 output pkts 239 in bytes 15223 out bytes 14062 dropped pkts 0 in FECN pkts 0 in BECN pkts 0 out FECN pkts 0 out BECN pkts 0 in DE pkts 0 out DE pkts 0 out bcast pkts 17 out bcast bytes 3264 PVC create time 00:11:32, last time PVC status changed 00:11:32 Router1# The output from the show frame-relay lmi command confirms the role of Router1 as a FR DCE device (FR switch). The output shows Router1 receiving status status enq from Router2 and also shows Router1 returning status messages to Router 2. Router1#show frame-relay lmi LMI Statistics for interface Serial0 (Frame Relay DCE) LMI TYPE = CISCO Invalid Unnumbered info 0 Invalid Prot Disc 0 Invalid dummy Call Ref 0 Invalid Msg Type 0 Invalid Status Message 0 Invalid Lock Shift 0 Invalid Information ID 0 Invalid Report IE Len 0 Invalid Report Request 0 Invalid Keep IE Len 0 Num Status Enq. Rcvd 72 Num Status msgs Sent 71 http://www.cisco.com/warp/public/125/frbacktoback_hybrid.html (4 of 6) [4/19/2001 9:01:11 PM] Back-to-Back Frame Relay Hybrid Switching - External Link Num Update Status Sent 0 Num St Enq. Timeouts 0 Router1# You can see FR status enquires and replies by using the debug frame-relay lmi command. Router1#debug frame-relay lmi Jul 12 14:21:45.667: Serial0(in): StEnq, myseq 112 Jul 12 14:21:45.671: RT IE 1, length 1, type 1 Jul 12 14:21:45.671: KA IE 3, length 2, yourseq 115, myseq 112 Jul 12 14:21:45.675: Serial0(out): Status, myseq 113, yourseen 115, DCE up Jul 12 14:21:55.587: Serial0(in): StEnq, myseq 113 Jul 12 14:21:55.587: RT IE 1, length 1, type 1 Jul 12 14:21:55.591: kA IE 3, length 2, yourseq 116, myseq 113 Jul 12 14:21:55.591: Serial0(out): Status, myseq 114, yourseen 116, DCE up The output from show frame-relay pvc command on Router2 confirms its function as a FR DTE device and shows an active PVC. Router2#show frame-relay pvc PVC Statistics for interface Serial0 (Frame Relay DTE) Active Inactive Deleted Static Local 1 0 0 0 Switched 0 0 0 0 Unused 0 0 0 0 DLCI = 101, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0 input pkts 275 output pkts 239 in bytes 15760 out bytes 16794 dropped pkts 2 in FECN pkts 0 in BECN pkts 0 out FECN pkts 0 out BECN pkts 0 in DE pkts 0 out DE pkts 0 http://www.cisco.com/warp/public/125/frbacktoback_hybrid.html (5 of 6) [4/19/2001 9:01:11 PM] [...]... frame- relay lmi-type frame- relay local-dlci frame- relay map frame- relay map bridge frame- relay map clns frame- relay map ip tcp header-compression frame- relay mincir frame- relay multicast-dlci frame- relay payload-compress frame- relay priority-dlci-group frame- relay priority-group frame- relay pvc frame- relay qos-autosense frame- relay route frame- relay svc frame- relay switching frame- relay traffic-rate frame- relay. .. PM] Frame Relay Commands Table of Contents Frame Relay Commands class (map-list) class (virtual circuit) clear frame- relay- inarp encapsulation frame- relay fr-atm connect dlci frame- relay adaptive-shaping frame- relay bc frame- relay be frame- relay becn-response-enable frame- relay broadcast-queue frame- relay cir frame- relay class frame- relay custom-queue-list frame- relay de-group frame- relay de-list frame- relay. .. frame- relay traffic-shaping interface fr-atm keepalive (LMI) map-class frame- relay map-group map-list show frame- relay end-to-end keepalive show frame- relay fragment show frame- relay ip tcp header-compression show frame- relay lapf show frame- relay lmi show frame- relay map show frame- relay pvc show frame- relay qos-autosense show frame- relay route show frame- relay svc maplist show frame- relay traffic Frame. .. map-class frame- relay jamaica frame- relay cir in 2000000 frame- relay mincir in 1000000 frame- relay cir out 15000 frame- relay mincir out 10000 frame- relay bc in 15000 frame- relay bc out 9600 frame- relay be in 10000 frame- relay be out 10000 frame- relay idle-timer 30 Related Commands Command Description frame- relay be Sets the incoming or outgoing excess burst size (Be) for a Frame Relay VC frame- relay cir... frmr frame- relay lapf k frame- relay lapf n200 frame- relay lapf n201 frame- relay lapf t200 frame- relay lapf t203 frame- relay lmi-n391dte frame- relay lmi-n392dce frame- relay lmi-n392dte frame- relay lmi-n393dce frame- relay lmi-n393dte http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/wan_r/wrdfrely.htm (1 of 135) [4/19/2001 9:02:26 PM] Frame Relay Commands frame- relay lmi-t392dce frame- relay. .. frame- relay end-to-end keepalive error-threshold frame- relay end-to-end keepalive event-window frame- relay end-to-end keepalive mode frame- relay end-to-end keepalive success-events frame- relay end-to-end keepalive timer frame- relay fair-queue frame- relay fragment frame- relay idle-timer frame- relay interface-dlci frame- relay intf-type frame- relay inverse-arp frame- relay ip tcp header-compression frame- relay. .. map-class frame- relay jamaica frame- relay cir in 2000000 frame- relay mincir in 1000000 frame- relay cir out 15000 frame- relay mincir out 10000 frame- relay bc in 15000 frame- relay bc out 9600 frame- relay be in 10000 frame- relay be out 10000 frame- relay idle-timer 30 http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/wan_r/wrdfrely.htm (15 of 135) [4/19/2001 9:02:26 PM] Frame Relay Commands... [4/19/2001 9:02:26 PM] Frame Relay Commands q frame- relay end-to-end keepalive mode q frame- relay end-to-end keepalive success-events q frame- relay end-to-end keepalive timer q frame- relay fair-queue q frame- relay fragment q show frame- relay end-to-end keepalive q show frame- relay fragment For Frame Relay configuration information and examples, refer to the "Configuring Frame Relay" chapter in the Cisco... Serial0 no ip address encapsulation frame- relay frame- relay traffic-shaping frame- relay class control-A map-class frame- relay control-A frame- relay adaptive-shaping foresight frame- relay cir 56000 frame- relay bc 64000 Related Commands Command Description frame- relay traffic-shaping Enables both traffic shaping and per-VC queueing for all PVCs and SVCs on a Frame Relay interface http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/wan_r/wrdfrely.htm... class to a DLCI for which a frame- relay map statement exists The framerelay interface-dlci command must also be used interface serial 0.2 point-to-multipoint frame- relay map ip 131.26.13.2 100 frame- relay interface-dlci 100 class slow_vcs interface serial 0 frame- relay interface-dlci 100 class fast_vc map-class frame- relay fast_vc frame- relay traffic-rate 56000 128000 frame- relay idle-timer 30 Related . Frame Relay Commands frame- relay lmi-t392dce frame- relay lmi-type frame- relay local-dlci frame- relay map frame- relay map bridge frame- relay map clns frame- relay. frame- relay lapf frmr frame- relay lapf k frame- relay lapf n200 frame- relay lapf n201 frame- relay lapf t200 frame- relay lapf t203 frame- relay lmi-n391dte frame- relay