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Frame Relay interface types - Part 3 (Subinterface - Point-to-Point)

We will wrap up this series configuring frame relay sub interface point-to-point for the third subnet 100.100.120.0/29. Refer the fig 1.3 below.



Remember from part1 we cannot use frame-relay map command on a point-to-point subinterface. We need to use "frame-relay interface dlci" command here for mapping L2/L3 address.

On R1 
interface Serial1/0.120 point-to-point
 ip address 100.100.120.1 255.255.255.248
 frame-relay interface-dlci 122

On R2 
interface Serial1/0.120 point-to-point
 ip address 100.100.120.2 255.255.255.248
 frame-relay interface-dlci 221 

Let us verify the mappings and connectivity.

R1#sh frame-relay pvc | i \ ACT
DLCI = 102, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial1/0
DLCI = 103, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial1/0
DLCI = 104, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial1/0
DLCI = 113, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial1/0.110
DLCI = 114, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial1/0.110
DLCI = 122, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial1/0.120

R1#sh frame-relay map
Serial1/0 (up): ip 100.100.100.2 dlci 102(0x66,0x1860), static,
              broadcast,
              CISCO, status defined, active
Serial1/0 (up): ip 100.100.100.3 dlci 103(0x67,0x1870), static,
              broadcast,
              CISCO, status defined, active
Serial1/0 (up): ip 100.100.100.4 dlci 104(0x68,0x1880), static,
              broadcast,
              CISCO, status defined, active
Serial1/0.110 (up): ip 100.100.110.3 dlci 113(0x71,0x1C10), static,
              broadcast,
              CISCO, status defined, active
Serial1/0.110 (up): ip 100.100.110.4 dlci 114(0x72,0x1C20), static,
              broadcast,
              CISCO, status defined, active
Serial1/0.120 (up): point-to-point dlci, dlci 122(0x7A,0x1CA0), broadcast
          status defined, activ 

R1#ping 100.100.120.2Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 100.100.120.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 16/34/76 ms 


R2#sh frame-relay pvc | i \ ACT
DLCI = 201, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial1/0
DLCI = 221, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial1/0.120 

R2#sh frame-relay map
Serial1/0 (up): ip 100.100.100.1 dlci 201(0xC9,0x3090), static,
              broadcast,
              CISCO, status defined, active
Serial1/0 (up): ip 100.100.100.3 dlci 201(0xC9,0x3090), static,
              CISCO, status defined, active
Serial1/0 (up): ip 100.100.100.4 dlci 201(0xC9,0x3090), static,
              CISCO, status defined, active
Serial1/0.120 (up): point-to-point dlci, dlci 221(0xDD,0x34D0), broadcast
          status defined, active

R2#ping 100.100.120.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 100.100.120.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 16/32/68 ms

Points to note on frame-relay interface point-to-point
  • Split horizon is enabled by default.
  • We can map only one DLCI per point-to-point subinterface using "frame-relay interface-dlci" command.
  • "frame-relay map ip" command cannot be used on point-to-point subinterface.
  • Each point-to-point subinterface should be part of separate subnet.
  
End of part 3     part1 (Frame Relay Physical Interface)      part2 (Frame Relay Sub interface Multipoint)
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