I have two routers connected and running IBGP between two of them and I am able to ping each other.
But later I replace one of the router with same configuration and now I am unable to ping the other router, the replaced new router is of same vendor.
May I know why this is happening.
Do you see a correct peering between them?
If your routers are directly connected to mount iBGP sessions, you can't ping the direct connected interface, is that right?
Could you explain a little bit more your issue and maybe a quick sketch would help.
I understand that point however what do you mean by unable to ping:
- Ping connected interfaces ?
- Is there a router in the middle or they are directly connected with a cable?
- Does iBGP session came out
Even you copied the configuration, the issue could be physical, or logical.
In order to help, I need to understand a bit more your design, configuration
Refer to the Cisco live presentation:
It shows show to troubleshoot peering down issues.
Hope this helps.
Ok if you are trying to ping the other end device from the cable and you insure that subnet is correctly configured, you have to troubleshoot from layer 1.
- Is it Ethernet cable or fiber?
- Does cable is ok?
- If SFP are used for fiber and/or ethernet, does the SFP is ok?
- Speed/Duplex configuration from interface
- If physical layer is ok then move on next steps:
- Switch in between?
- Route to null (sometimes on exam they love doing such stuff....)
But if you have trust config that are exactly the same, the only issue could be physical or logical (interface missconfigured, shutdown,...)
The idea is to begin from layer 1 and going step by step.
The reason for the issue can be a bad port or SFP (if you are using fiber).
One way to troubleshoot would be to perform a ping test to the connected device. If the connected device is a Cisco router, then you can run "show ip traffic | in echo" and see if the ECHO received counters and echo-reply sent counter are incrementing or not.
You can verify the same command on the problematic router and see if you are seeing the Echo sent counters and Echo-reply received counter incrementing.
Hope this helps.
iBGP is it up now ?
Each router are directly connected ? or connected to the same LAN ?
if you can show us : show ip interface brief, show ip bgp summary of the both router it will be more easy to help you