Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

How to detect the port normal or fault ?


R1                 R2

s0------------|s0 |



At first I ping the R1's IP address from R2, there are many packets discarded, then I ping the R2's IP address from itself, there are many packets discarded too, finally I ping the R2's IP address from a pc,there is no packets discarded.

I know the WAN leased circuit is not normal,I Wonder the second ping discards packet,but the third ping doesn't discard packet.Why???

Would you help me? I am waiting for your answer anxiously.

New Member

Re: How to detect the port normal or fault ?

The problem resides in WAN leased line only. As the packets are discarded in the second try to its own interface, try chaning the interface to s1 or any one to verify that your interface is not faulty. and enable the icmp debugs to narrow down the problem.

Also refer this link to troubleshoot the problem.


Re: How to detect the port normal or fault ?


Nothing to wonder. Your router is quite working normally, there is a problem with your link b/w R1 & R2.

The clarification for your wonder is as follows.

From R2, while pinging to R1's IP address, just it will get a reply from R1. But in serial links, when you are trying to ping to it's own IP address, then the path is ping REQUEST-- R2 --> R1 --> R2 and then it'll take REPLY and same reverse path i.e R2 --> R1 --> R2. Total round trip path is two times than pinging to remote router IP. Observe that even time delay of ping to R2 from R2 is approx twice the delay of ping to R1 from R2 (In case of pinging to Serial interfaces IP's only).



With best regards... Ashok ----------- Pls kindly rate if helpful or answered your question.
New Member

Re: How to detect the port normal or fault ?

Ashok is correct. When you ping a router serial interface from the router, the ping traverses the WAN link. That's why you cant ping your own interface is the WAN link is down.


CreatePlease login to create content