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Community Member

How to troubleshoot EIGRP issue?

We have user report one-way audio issue. Trace the destination address 10.10.169.136 from the source switch a couple of times. We recieved total different result. Please see the below:

IDFA#trace 10.10.169.136

1 10.210.20.3 0 msec 4 msec 0 msec

2 10.210.36.2 0 msec

10.210.247.2 4 msec

10.210.170.2 !A

IDFA#trace 10.10.169.136

1 10.210.20.3 0 msec 0 msec 0 msec

2 10.210.170.2 !A * !A

IDFA# trace 10.10.169.136

1 10.210.20.3 0 msec 0 msec 4 msec

2 10.10.95.2 4 msec

10.210.247.2 0 msec

10.10.95.2 0 msec

3 10.252.1.170 8 msec 16 msec

10.210.170.2 !A

We are using EIGRP routing protocol and it seems that 10.210.170.2 is show stopper, right?

Can anyone tell me what we can tell from the result? how to troubleshoot it?

Thanks a lot,

Jessica

8 REPLIES

Re: How to troubleshoot EIGRP issue?

Is auto-summary off?

Mike

Community Member

Re: How to troubleshoot EIGRP issue?

no auto-summary

Hall of Fame Super Gold

Re: How to troubleshoot EIGRP issue?

Jessica

The main thing that you can tell from the result is that 10.210.170.2 is configured with an access list which is denying your traceroute. The response of !A is an indication of "administratively prohibited" which is generated when an access list denies the packet.

The other thing that you can tell is that the next hop device (router) with address 10.210.20.3 has multiple paths toward that destination address.

It is not clear whether either of these things has any bearing on your original problem of one way audio.

[edit] since all of the addresses shown are within the same major network of 10.0.0.0 then I do not see where auto-summary or no auto-summary makes any difference.

HTH

Rick

Re: How to troubleshoot EIGRP issue?

Rick,

I am still learning EIGRP and did not realize the !A was due to an access list....thanks for the info.

Mike

Hall of Fame Super Blue

Re: How to troubleshoot EIGRP issue?

Mike

the !A is to do with traceroute rather than anything to do with EIGRP. Attached is a doc that shows what all the possible characters produced on a traceroute mean -

http://www.cisco.com/en/US/products/sw/iosswrel/ps1831/products_tech_note09186a00800a6057.shtml#traceroute

Jon

Community Member

Re: How to troubleshoot EIGRP issue?

Rick -

Thanks so much for the information. I didn't know what !A means either.

10.210.20.3 is one of our Core layer-3 switch. What I should do to start troubleshooting this issue? Or which commands are useful for tracing down the issue?

Thanks a lot.

Hall of Fame Super Gold

Re: How to troubleshoot EIGRP issue?

Jessica

With the limited information we have it is a bit difficult to know what would be the best troubleshooting. If we knew more about what is the application and what is the topology of the network we could probably give better advice.

But based on what we know so far, here is what I would suggest:

- since each of the traceroutes stop at 10.210.170.2 would we be correct in assuming that this might be one hop before the destination address?

- go hop by hop through the network, looking at each of the devices through which the traffic might pass. Check to see if there might be an access list which might be denying the audio one way. Check to see if the device has a valid route to the source and to the destination (and does that route make sense based on what you know of the network topology). Check to see if there might be any RPF check configured which might be denying the audio in one direction.

HTH

Rick

Community Member

Re: How to troubleshoot EIGRP issue?

I will try it. Thanks a lot.

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