Content

| 4.5 |  | Troubleshooting Frame Relay |
| 4.5.6 |  | Ping the local IP address on a multipoint Frame Relay |

A ping performed on the local IP address on a multipoint Frame Relay interface does not work. This is because Frame Relay multipoint physical and subinterfaces are non-broadcast. Recall that Ethernet and point-to-point interfaces such as High-Level Data Link Control (HDLC) and Frame Relay point-to-point sub-interfaces are broadcast. Because multipoint interfaces can have multiple destinations, the router must have a mapping for every destination. The router does not have any Layer 3 to Layer 2 mapping for its own address and does not know how to encapsulate the packet. An encapsulation failure results.

Furthermore, ping is unsuccessful from one spoke to another in a hub and spoke configuration. This is because there is no mapping for the local IP address, and none were learned by way of Inverse ARP. But if a static map is configured with the frame-relay map command for the local IP address or one for the remote spoke to use the local DLCI, ping will be successful.

Before adding the static Frame-Relay map, the result of pinging a local interface will be as follows:

> Router#ping 3.1.3.3
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to 3.1.3.3, timeout is 2 seconds:
> .....
> Success rate is 0 percent (0/5)

In order to permit the pinging of local Frame-Relay interfaces, the following static map command must be added:

> Router#configure terminal

> Enter configuration commands, one per line. End with CNTL/Z.

> Router(config)#interface serial 0/1
> Router (config-if)#frame-relay map ip 3.1.3.3 160

This can be verified using the show frame-relay map command:

> Router#show frame-relay map
> Serial0/1 (up): ip 3.1.3.1 dlci 180(0xA0,0x2800), dynamic, broadcast, status defined, active
> Serial0/1 (up): ip 3.1.3.2 dlci 160(0xA0,0x2800), static, CISCO, status defined, active
> Serial0/1 (up): ip 3.1.3.3 dlci 160(0xA0,0x2800), static, CISCO, status defined, active

It will now be possible to ping the local interface:

> Router#ping 3.1.3.3

> Type escape sequence to abort.

> Sending 5, 100-byte ICMP Echos to 3.1.3.3, timeout is 2 seconds:
> !!!!!

> Success rate is 100 percent (5/5), round-trip min/avg/max = 64/68/76 ms

The running configuration file for Serial 0/1 is reproduced below:

> interface Serial0/1
> ip address 3.1.3.3 255.255.255.0
> no ip directed-broadcast
> encapsulation frame-relay
> frame-relay map ip 3.1.3.2 160
> frame-relay map ip 3.1.3.3 160
> frame-relay interface-dlci 160
> !