Cisco Router as a Frame Relay Switch

Cisco router can act as frame relay switch with special configuration little different from point-to-point router use frame-relay encapsulation to create 2 or more link logical. Because of a Cisco router can generate clock so can act as DCE device like if we create link point-to-point using HDLC encapsulation, one of side serial interface must set as DCE use clock rate.

To configure a Cisco router as a Frame Relay switch, follow the configuration steps below

1#
enable Frame Relay switching

(config)# frame-relay switching

2#
set encapsulation in the interface serial

(config-if)# encapsulation frame-relay

3#
configure the interface as a DCE interface

(config-if)# frame-relay intf-type dce

4#
specify incoming DLCI, outgoing interface and outgoing DLCI, Frame Relay switching can be configured only on physical interfaces

5#
set clockrate on serial interface of the Frame Relay switch. it provides clocking signals to the connected Frame Relay routers, which set up as DTE

#example

R1 --- (DLCI 100) R-FRSW (DLCI 200) --- R2

R1 : 10.10.10.1/24
R2 : 10.10.10.2/24

R-FRSW as Frame-Relay Switch

R-FRSW#
frame-relay switching
!
interface Serial1/0
 no ip address
 encapsulation frame-relay
 serial restart_delay 0
 clockrate 64000
 frame-relay intf-type dce
 frame-relay route 100 interface Serial1/1 200
!
interface Serial1/1
 no ip address
 encapsulation frame-relay
 serial restart_delay 0
 clockrate 64000
 frame-relay intf-type dce
 frame-relay route 200 interface Serial1/0 100

R-FRSW#sh frame-relay ?
  end-to-end     Frame-relay end-to-end VC information
  fragment       show frame relay fragmentation information
  ip             show frame relay IP statistics
  lapf           show frame relay lapf status/statistics
  lmi            show frame relay lmi statistics
  map            Frame-Relay map table
  multilink      Show Multilink Frame Relay bundle information
  pvc            show frame relay pvc statistics
  qos-autosense  show frame relay qos-autosense information
  route          show frame relay route
  svc            show frame relay SVC stuff
  traffic        Frame-Relay protocol statistics
  vc-bundle      FR VC-Bundle
  vofr           Show frame-relay VoFR statistics

R-FRSW#sh frame-relay route
Input Intf      Input Dlci      Output Intf     Output Dlci     Status
Serial1/0       100             Serial1/1       200             active
Serial1/1       200             Serial1/0       100             active

Router 1

R1#
interface Serial1/0
 ip address 10.10.10.1 255.255.255.0
 encapsulation frame-relay
 serial restart_delay 0

R1#sh frame-relay map
Serial1/0 (up): ip 10.10.10.2 dlci 100(0x64,0x1840), dynamic,
              broadcast,, status defined, active

Router 2

R2#
interface Serial1/0
 ip address 10.10.10.2 255.255.255.0
 encapsulation frame-relay
 serial restart_delay 0

R2#sh frame-relay pvc 200
PVC Statistics for interface Serial1/0 (Frame Relay DTE)

DLCI = 200, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial1/0

  input pkts 6             output pkts 6            in bytes 554       
  out bytes 554            dropped pkts 0           in pkts dropped 0         
  out pkts dropped 0                out bytes dropped 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 1         out bcast bytes 34        
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
  pvc create time 00:02:07, last time pvc status changed 00:01:47
  
R2#sh frame-relay map
Serial1/0 (up): ip 10.10.10.1 dlci 200(0xC8,0x3080), dynamic,
              broadcast,, status defined, active