Frame-Relay Switch and Bridge

Here is the following scenario:

First we will have to configure FRS, which is 2961 IOS router, to a frame-relay switch.

The logic is quite simple with 3 simple steps:

      1. Enable frame-relay switching using the command: frame-relay switching

      2. Configure each of the interfaces with frame-relay configuration:

interface Serial0/0  no ip address  encapsulation frame-relay  clock rate 128000  frame-relay intf-type dce ! interface Serial0/1  no ip address  encapsulation frame-relay  clock rate 128000  frame-relay intf-type dce

No IP address, encapsulation frame-relay, clock rate and most important interface type which should be, on the service provider side, set to DCE (the default is DTE which should be on the CPE side).

     3.        Bond the two interfaces using the connect command:

connect R1_R2 serial 0/0 102 serial 0/1 201

Now let’s configure R1 and R2 CPE routers for frame-relay connection.

R1 Configuration:

interface Serial0/0  ip address 10.0.12.1 255.255.255.0  encapsulation frame-relay  clock rate 128000  frame-relay map ip 10.0.12.2 102 broadcast  frame-relay interface-dlci 102  no frame-relay inverse-arp end

R2 Configuration:

interface Serial0/0  ip address 10.0.12.2 255.255.255.0  encapsulation frame-relay  clock rate 128000  frame-relay map ip 10.0.12.1 201 broadcast  frame-relay interface-dlci 201  no frame-relay inverse-arp end

Note that due to the fact that we are configuring on the physical interface, which connected to frame-relay cloud, we have to configure a static map between R1 and R2 or enable inverse-arp.

While showing frame-relay mapping:

R2#sh frame-relay map

Serial0/0 (up): ip 10.0.12.1 dlci 201(0xC9,0x3090), static,

              broadcast,

              CISCO, status defined, active

The static statement indicates frame-relay static map where if we had enable inverse-arp we will see the dynamic statement as follows:

R2#sh frame-relay map

Serial0/0 (up): ip 10.0.12.1 dlci 201(0xC9,0x3090), dynamic,

              broadcast,, status defined, active

Else we can configure logical interface with point-to-point configuration:

R1 Configuration:

interface Serial0/0  no ip address  encapsulation frame-relay  clock rate 128000 ! interface Serial0/0.12 point-to-point  ip address 10.0.12.1 255.255.255.0  snmp trap link-status  frame-relay interface-dlci 102

R2 Configuration:

interface Serial0/0  no ip address  encapsulation frame-relay  clock rate 128000 ! interface Serial0/0.21 point-to-point  ip address 10.0.12.2 255.255.255.0  snmp trap link-status  frame-relay interface-dlci 201

Show frame-relay map indicates point-to-point network type:

R2#sh frame-relay map

Serial0/0.21 (up): point-to-point dlci, dlci 201(0xC9,0x3090), broadcast

          status defined, active

Now let’s assume that we want to bridge over the frame-relay network between BB1 and BB2, which reside on the same segment.

First I cleared R1 and R2 serial interfaces using the command: default interface serial 0/0

R1 bridging configuration:

bridge 1 protocol ieee ! bridge irb ! interface FastEthernet0/0  no ip address  duplex auto  speed auto  bridge-group 1 ! interface Serial0/0  no ip address  encapsulation frame-relay  clock rate 128000  frame-relay map bridge 102 broadcast  bridge-group 1

R2 bridging configuration:

bridge 1 protocol ieee ! bridge irb ! interface FastEthernet0/0  no ip address  duplex auto  speed auto  bridge-group 1 ! interface Serial0/0  no ip address  encapsulation frame-relay  clock rate 128000  frame-relay map bridge 201 broadcast  bridge-group 1

Now BB1 can ping BB2:

BB1#ping 10.0.12.252

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 10.0.12.252, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 20/54/100 ms