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New Member

Unable to ping Routers Frame relay own interface IP

Hi all,

I have question about frame Relay.

Serial int of Router is config with IP address.

2650Router#sh run int se0/0
Building configuration...

Current configuration : 152 bytes
!
interface Serial0/0
ip address 192.168.1.2 255.255.255.0
encapsulation frame-relay
no keepalive
frame-relay map ip 192.168.1.1 102 broadcast

OSPF is running here on interface se0/0

I can ping the Remote Router IP but not the

650Router#ping 192.168.1.1************************************************nei router

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms
2650Router#ping 192.168.1.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.1.2, timeout is 2 seconds:*****************************************
.....

Thanks

mahesh

1 ACCEPTED SOLUTION

Accepted Solutions
New Member

Unable to ping Routers Frame relay own interface IP

Hi Mahesh,

to ping your own interface on frame relay you will need to map the interface IP. You will need to add the following command -

frame-relay map ip 192.168.1.2 102

This should help.

Regards,

Pawan Sharma

http://www.ebrahma.com

6 REPLIES
New Member

Unable to ping Routers Frame relay own interface IP

Hi Mahesh,

to ping your own interface on frame relay you will need to map the interface IP. You will need to add the following command -

frame-relay map ip 192.168.1.2 102

This should help.

Regards,

Pawan Sharma

http://www.ebrahma.com

New Member

Unable to ping Routers Frame relay own interface IP

Hi Pawan,

Many thanks it worked.

MAhesh

New Member

Unable to ping Routers Frame relay own interface IP

The reason you can't ping is because whenever you send ping to the frame-relay switch, the frame-relay switch doesn't know how to reac to you, in other words, it doesn't know which DLCI is attached with your IP, so that is why it is getting drop. You need a frame-relay map statement to your own IP. btw, this issue is only with multi-poing sub-interfaces.

It wouldn't be a problem with point-to-point interfaces.

Regards,

Manouchehr

Cisco Employee

Unable to ping Routers Frame relay own interface IP

Manouchehr,

The reason you can't ping is because whenever you send ping to the  frame-relay switch, the frame-relay switch doesn't know how to reac to  you, in other words, it doesn't know which DLCI is attached with your  IP, so that is why it is getting drop.

I respectfully disagree. A Frame Relay switch has nothing to do with this issue. A Frame Relay switch is concerned exclusively with input and output DLCIs and interfaces, and it has absolutely no idea what's carried inside the frame, IP packet or anything else. Rather, it is the problem of the sender itself, i.e. of the sending router. Whenever a router is sending an IP packet through a Frame Relay interface, it must find the mapping for the next-hop IP address in the IP/DLCI mapping table associated with the particular outbound interface. Even if a router pings itself - its own IP address assigned to its Frame Relay interface, it searches for the IP/DLCI mapping. If the mapping is not present although according to the routing table, the IP address is reachable through that particular interface, the packets will get lost. This is the phenomenon that is observed so frequently.

In fact, all serial technologies work this way - if a router pings itself, the packet is sent to a neighbor over the serial link, and rerouted back to the router itself.

Best regards,

Peter

New Member

Unable to ping Routers Frame relay own interface IP

Peter is absolutely right here.

Since it is a Frame-relay encapsulation, hence we need a Layer 2 Frame through DLCI to be formed for any destination.

Since the destination is one of the connected interface which has a frame-relay encapsulation, router will first find a layer 2 address for the packet to get encapsulated as a frame for which we need DLCI ( mac address in case of Ethernet -which is available via ARP)

Hence whenever we need to ping any IP which goes out of a Frame relay interface we need a layer 3 to layer 2 mapping which in this case is DLCI.

Regards,

Vinayak

New Member

Unable to ping Routers Frame relay own interface IP

Hi Mahesh,

You are welcome anytime !!!

Regards,

Pawan Sharma

http://www.ebrahma.com

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