why I cannot ping my own router's interfaces ?

[Johnthom]

Hi all,
I have just set up a simple network to connect my head office and remote branch. This network consists of two Cisco 2500 routers, and Catalyst 1900 switches, two router are encapsulated with Frame Relay. Generally speaking, I configured my routers with very simple configuration, and my network run very well, but there is only one strange phenomenon I could not understand. That was when I connected a terminal to console port on the first router, I can ping all interfaces of every devices in the network except this router's interfaces
. Similarly, when I connect terminal to console port of the second router, I can ping to the first router's interfaces except for the second router's interfaces !!! I have asked many my colleagues but not get answers, and they told that they have experienced the same issue and didn't know why.
Please give me an explanation about this problem.
Thanks very much for any help.
John Thom

 

[Kiera]

Have you gotten your answer on this post

 

[mavenccie]

Isn't that an interesting phenomena? To be able to ping the router's own interface on Cisco's Frame relay, you need to setup a frame map to a DLCI that is being used on that port for that particular IP network that you are trying to ping. So in essence, you will be sending the ping packet down the DLCI to the other router, and then back. If you are using point-to-point interface, this is already done. That is because on a point-to-point interface, all packets are mapped to the DLCI and sent. On a normal frame relay interface or a point-to-multipoint interface, you need the add the following:
frame-relay map ip <your router's own IP address> <a DLCI in use>
And of course the other side should already have the proper mappings whether it be normal frame, point-to-point, or point-to-multipoint.
And Voila, you are able to ping your own interface.

 

[Gaz555]

one more thing i would like to know.....if there is a workstation running on ipx with out ethernic card,,,then for its layer 3 which physical address (mac address) will it use.

 

[mavenccie]

If it doesn't have an ethernet card, it will have some kind of node address that it uses. Whether it be from a token ring or FDDI or etc. card. If not, it will be configurable or it will arbitrarily choose a node address. For instance, a Novell Server itself has an Internal Network Number. This network number represents the server itself. The node number of the IPX address is equal to 0000.0000.0001. And resources from this server are advertised via this Internal Network Number. Does that answer your question, and clarify it for you? -Later

 

[BOJIKA]

Frame Relay interfaces cannot be pinged by the local router unless the Telco has setup a loopback PVC. Selecting A as an answer, is not a good choice because pinging from a router connected to one of the Frame Router's LAN interfaces would still not get a response.

The loopback interface command is used to loopback the interface to the telco for testing of the WAN local loop.

 

[mavenccie]

To Bojika - There is always more than one way to skin a cat in the IOS. Try the solution I outlined, and it will work. Even though there really shouldn't be a need to ping the router's own local interface, it sometimes gives engineers the piece of mind that they can.