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Configuring a cisco router as a frame relay switch
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Configuring a cisco router as a frame relay switch

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How to configure a cisco router as a frame relay switch?

How to configure a cisco router as a frame relay switch?

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    Configuring a cisco router as a frame relay switch Configuring a cisco router as a frame relay switch Document Transcript

    • How to Configure a Cisco Router as a Frame Relay Switch?A Cisco router now has the capability to simulate a Frame Relay switch. Although thisappendix will not show you how configure all of the features that a true Frame Relayswitch will have, it will show you how to configure a Cisco router to propagate DLCIsand match them to the appropriate outgoing interfaces to make the router act as aFrame Relay switch.The most important thing to remember about a Frame Relay switch in the lab is thatthe DLCI is sent through LMI out a particular interface, and then that DLCI andinterface are mapped to an outgoing DLCI and interface.Physical Connections to the Frame Relay Switch (Cisco 2523)Before you start configuring the Frame Relay switch, take a look at how the labrouters are connected to the Cisco 2523 acting as the Frame Relay switch. FigureB-7 illustrates the physical connections.Figure B-7 Frame Relay Physical ConnectionsAs you can see from Figure B-7, R3 will be the "hub" site and requires two PVCs andDLCIs to be configured on interface S0 of the Cisco 2523. R2 and R4 need only onePVC and one DLCI. Begin by configuring the router as a Frame Relay switch.Steps for Configuring a Cisco Router as a Frame Relay SwitchTable B-1 defines the steps to configuring a Cisco router as a Frame Relay switch.Table B-1. Configuring a Cisco Router as a Frame Relay SwitchStep Description CommandStep Enable Frame Relay switching. frame-relay switching1Step Configure Frame Relay encapsulation2 encapsulation, Frame Relay LMI frame-relay frame-relaylmi-type http://www.router-switch.com/
    • Step Description Command type, Frame Relay DCE interface ansi frame-relay intf-type dce clock rate mode, and clock rate on 64000 individual interfaces.Step Configure DLCI to interface frame-relay3 mappings on individual route {local-dlci} interface {outgoing interfaces. interface and number} {outgoing-dlci}The first thing is to connect to the Cisco 2523s console port. There is noconfiguration on the router at this point. You should be in setup mode or atthe Router> prompt. If you are in setup mode, just exit this mode (Ctrl-c).When you are into the router, give it a host name of Frame-Switch.Router>enRouter#config tEnter configuration commands, one per line. End with CNTL/Z.Router(config)#hostname Frame-SwitchDo not worry about passwords and Telnet connectivity. This router will be astandalone Frame Relay switch. If you need to access it, you will connect to theconsole port.Begin with the first step documented in Table B-1, and enable Frame Relay switchingon the router. Example B-1 illustrates this configuration step.Example B-1. Enable Frame Relay SwitchingFrame-Switch(config)#frame-relay switchingFrame-Switch(config)#After the Frame Relay switching process has been started, configure the individualinterfaces for the Frame Relay switch. This includes changing the encapsulation typeto frame-relay and changing the LMI type to ANSI. Because all interfaces on theFrame Relay switch are DCEs (refer to the Figure B-7), they will need to be changedto the FrameRelay type DCE and must have the clock rate command issued as well. Example B-2demonstrates these commands for interface Serial0.Example B-2. Frame-Relay Commands for Serial0Frame-Switch(config)#int serial0Frame-Switch(config-if)#encapsulation frame-relayFrame-Switch(config-if)#frame-relay lmi-type ansiFrame-Switch(config-if)#frame-relay intf-type dce http://www.router-switch.com/
    • Frame-Switch(config-if)#clock rate 64000Now that all the Frame Relay commands have been set, you need to map the localDLCI of this interface to the outgoing DLCI and port. Because the Serial0 interface hastwo PVCs, it needs two mappings. Example B-3 shows the commands.Example B-3. DLCI-to-Interface Mappings for Serial0Frame-Switch(config-if)#frame-relay route 100 interface serial 2101Frame-Switch(config-if)#frame-relay route 200 interface serial 1201Frame-Switch(config-if)#no shutdownFrom Figure B-7, you know that Serial 0 has two PVCs, one to R2 and one to R4. Thefirst highlighted portion of lines 1 and 2 in Example B-3 point out the local DLCI thatwill be advertised out Serial 0. Therefore, R3 will see DLCI 100 and DLCI 200 becauseR3 is connected to the Frame Relay switch on Serial0. The second portion ofhighlighting in lines 1 and 2 marks the outgoing interface to which each DLCI ismapped. Therefore, anything coming from R3 on DLCI 100 will be sent to Serial2, andanything coming from R3 on DLCI 200 will be sent to Serial1. The last portion ofhighlighting in lines 1 and 2 indicates the DLCI assigned to the outgoing port. So,anything coming from R3 on DLCI 100 will go out Serial2 to DLCI 101, and anythingcoming from R3 on DLCI 200 will go out Serial1 to DLCI 201. Dont forget to removethe interfaces from shutdown mode.The next thing you need to do is perform a similar mapping statement on interfacesSerial1 and Serial2, except that the numbers will be reversed. See Example B-4.Example B-4. Frame Relay Commands and DLCI-to-Interface Mappings for Serial1Frame-Switch(config)#interface serial1Frame-Switch(config-if)#encapsulation frame-relayFrame-Switch(config-if)#frame-relay lmi-type ansiFrame-Switch(config-if)#frame-relay intf-type dceFrame-Switch(config-if)#clock rate 64000Frame-Switch(config-if)#frame-relay route 201 interface serial 0200Frame-Switch(config-if)#no shutdownThe highlighted portion of the configuration shows the local DLCI (201), the outgoinginterface (Serial0), and the outgoing DLCI (200). Next, do the same for interfaceSerial2. See Example B-5.Example B-5. Frame-Relay Commands and DLCI-to-Interface Mappings on Serial2 http://www.router-switch.com/
    • Frame-Switch(config)#interface serial2Frame-Switch(config-if)#encapsulation frame-relayFrame-Switch(config-if)#frame-relay lmi-type ansiFrame-Switch(config-if)#frame intf-type dceFrame-Switch(config-if)#clock rate 64000Frame-Switch(config-if)#frame-relay route 101 interface serial 0100Frame-Switch(config-if)#no shutFrame-Switch(config-if)#The highlighted portion of the configuration shows the local DLCI (101), the outgoinginterface (Serial0), and the outgoing DLCI (100). At this point, you have a functionalFrame Relay switch. You will be able to verify the connections in Chapter 7, "RouterInterface Configuration," but for now, take a look at the configuration and do a showframe-relay route to verify that the configuration matches the lab diagram. ExampleB-6 shows the running-config file. Notice where the commands are located in theconfiguration file.Example B-6. Output from show running-configFrame-Switch#show running-configBuilding configuration...Current configuration:!version 11.2no service password-encryptionno service udp-small-serversno service tcp-small-servers!hostname Frame-Switch!!frame-relay switching!interface Serial0noip addressencapsulation frame-relayclockrate 64000frame-relaylmi-type ansiframe-relayintf-type dceframe-relay route 100 interface serial2 101frame-relay route 200 interface Serial1 201! http://www.router-switch.com/
    • interface Serial1noip addressencapsulation frame-relayclockrate 64000frame-relaylmi-type ansiframe-relayintf-type dceframe-relay route 201 interface Serial0 200!interface Serial2noip addressencapsulation frame-relayclockrate 64000frame-relaylmi-type ansiframe-relayintf-type dceframe-relay route 101 interface Serial0 100!interface Serial3noip addressshutdown!interface Serial4noip addressshutdown!interface Serial5noip addressshutdown!interface Serial6noip addressshutdown!interface Serial7noip addressshutdown!interface Serial8noip addressshutdown!interface Serial9noip addressshutdown http://www.router-switch.com/
    • !interface TokenRing0noip addressshutdown!interface BRI0noip addressshutdown!noip classless!!line con 0exec-timeout 0 0line aux 0linevty 0 4login!endFrame-Switch#The highlighted portions illustrate all the Frame Relay configuration tasks that youcompleted. Notice that none of the interfaces has IP addresses, nor do any of theinterfaces need them. You are only mapping DLCIs to interfaces. This is a Layer 2function, not a Layer 3 function, therefore, no IP address are needed.The show frame-relay route command is a useful command in determining that yourconfiguration is correct. Example B-7 shows the output from this command.Example B-7. Output from show frame-relay route CommandFrame-Switch#show frame-relay routeInput Intf Input Dlci Output Intf Output Dlci StatusSerial0 100 Serial2 101 inactiveSerial0 200 Serial1 201 inactiveSerial1 201 Serial0 200 inactiveSerial2 101 Serial0 100 inactiveFrame-Switch#From this output, you can see that the Input Dlci matches the correct interfaces fromthe lab diagram in Figure B-7. You also can see that Output Intf and OutputDlci match to the correct interfaces and DLCIs as well. From here, you can assumethat everything is configured correctly. The status will be inactive until you configurethe Frame Relay interfaces on R2, R3, and R4 and remove them from shutdown http://www.router-switch.com/
    • mode.More Related Cisco Network Tips:How to Configure Cisco Routers as Frame Relay Switch (FRS)? http://www.router-switch.com/