Lab 5: Configuring a Frame Relay Switch-Part II

Lab 5: Configuring a Frame Relay Switch ”Part II

Lab Walkthrough

The Frame Relay switch in this lab functions as a fully meshed Frame Relay service. A fully meshed Frame Relay service has a PVC not only to a central site, but also to every other site. This can lead to several scaling problems when a large number of sites are involved. Some Layer 3 routing issues, such as split horizons, also can occur on a multipoint network. Chapter 5 discusses this in more depth.

To configure Frame Relay switching, you need to perform the following tasks :

Step 1. Enable Frame Relay switching.

Step 2. Configure interface LMI and Frame Relay interface type.

Step 3. Configure PVCs with the frame-relay route command.

First, enable Frame Relay switching using the frame-relay switching global command from configuration mode. Second, configure the serial interfaces for Frame Relay switching, as shown in Figure 1-17. To perform this, use the encapsulation frame-relay command, along with the commands frame-relay intf-type dce command and frame-relay lmi-type ansi on serial Interface 5. Example 1-53 highlights the Frame Relay switch configuration.

Example 1-53 Frame Relay Multipoint Configuration

  hostname frame_switch   !    frame-relay switching     -Enables Frame Relay switching   !   interface Ethernet0   no ip address   shutdown   !   interface Serial0   no ip address    encapsulation frame-relay     Sets Frame encapsulation    clockrate 56000     Sets the clockrate, needed for DCE interface    frame-relay intf-type dce     Sets Frame Relay to a DCE interface    frame-relay route 21 interface Serial1 112     Creates and maps DLCI 21 to DLCI   112 on Serial 1    frame-relay route 23 interface Serial5 32     Creates and maps DLCI 23 to DLCI 32   on Serial 5   !   interface Serial1   no ip address   encapsulation frame-relay   clockrate 56000   frame-relay intf-type dce    frame-relay route 112 interface Serial0 21     Creates and maps DLCI 112 to DLCI   21 on Serial 0    frame-relay route 113 interface Serial5 31     Creates and maps DLCI 113 to DLCI   31 on Serial 5   !   <<<text omitted>>>   !   interface Serial5   no ip address   encapsulation frame-relay   clockrate 56000    frame-relay lmi-type ansi     Sets the LMI type to ANSI versus Cisco  frame-relay intf-type dce   frame-relay route 31 interface Serial1 113     Creates and maps DLCI 31 to DLCI   113 on Serial 1    frame-relay route 32 interface Serial0 23     Creates and maps DLCI 32 to DLCI 23   on Serial 0   !  <<<text omitted>>> end 

To see if your Frame Relay switch is working, you need to configure the DTE, or router side of the network. When this is complete, the PVCs will become "active." Example 1-54 illustrates the Frame Relay configuration of R1, R2, and R3.

Example 1-54 The Significant Configuration Portions of R1, R2, and R3

  hostname r1   !   interface Serial0   ip address 172.16.17.1 255.255.255.0   encapsulation frame-relay   frame-relay map ip 172.16.17.2 112 broadcast   frame-relay map ip 172.16.17.3 113 broadcast   !  __________________________________________________________  hostname r2   !   interface Serial0   ip address 172.16.17.2 255.255.255.0   no ip directed-broadcast   encapsulation frame-relay   no ip mroute-cache   frame-relay map ip 172.16.17.1 21 broadcast   frame-relay map ip 172.16.17.3 23 broadcast   !  __________________________________________________________  hostname r3   !   interface Serial0   ip address 172.16.17.3 255.255.255.0   no ip directed-broadcast   encapsulation frame-relay   no ip mroute-cache   frame-relay map ip 172.16.17.1 31 broadcast   frame-relay map ip 172.16.17.2 32 broadcast   frame-relay lmi-type ansi  ! 

When this is complete, enter the show frame-relay route command to ensure that all connections are up and active. Also verify that LMI is correctly configured with the show frame-relay lmi command. These two commands manifest themselves in Example 1-55.

Example 1-55 The show frame-relay route and show frame-relay lmi Commands

 frame_switch#  show frame-relay route  Input Intf      Input Dlci      Output Intf     Output Dlci     Status Serial0         21              Serial1         112             active Serial0         23              Serial5         32              active Serial1         112             Serial0         21              active Serial1         113             Serial5         31              active Serial5         31              Serial1         113             active Serial5         32              Serial0         23              active frame_switch# frame_switch#  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 188              Num Status msgs Sent 188   Num Update Status Sent 0              Num St Enq. Timeouts 0 LMI Statistics for interface Serial1 (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 188              Num Status msgs Sent 188   Num Update Status Sent 0              Num St Enq. Timeouts 0 LMI Statistics for interface Serial5 (Frame Relay DCE) LMI TYPE = ANSI   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 185              Num Status msgs Sent 185   Num Update Status Sent 0              Num St Enq. Timeouts 1 frame_switch#