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Commands to troubleshoot M2PA or M3UA/SUA link flapping problems.

Hello there,


Just wanted to provide some steps to troubleshoot M2PA or M3UA/SUA based links. Although it is uncommon to see them flapping, it actually could occur due to different reasons.


In case of observing link flapping, I usually follow the below steps to further isolate the problem:


a) Obtain "show logging" output; which will include the link failure reason like the example below:


%CS7MTP3-3-LINKNOTUP: Link 0 in linkset 2-463_RMSGW1 failed. Reason=communication lost

b.1) For M2PA based links, obtain "show cs7 m2pa sctp parameters <linkset><slc>", and search "Num retrans:" and "Num times failed:" from the output. Please note that if the association is not established, theremight be no output at all. Also check the command "show cs7 m2pa sctp statistics <linkset> <slc>"

b.2) For XUA based links, use the following commands to getcorresponding information:


- "show cs7 asp | in <asp name>" to get the association id for this ASP.

- "show ip sctpassociation parameters <assoc id>"

c) Check the output of "show ip route <remote ip>" command, and find theinterface being used for the remote ip, like the example below:


7613#show ip route 192.168.70.242

Routing entry for 192.168.70.0/24

  Known via "connected", distance 0, metric 0 (connected, via interface)

  Routing Descriptor Blocks:

  * directly connected, via FastEthernet1/0/1

      Route metric is 0, traffic share count is 1

d) Check the "show interfaces <interface>" command, to see if there is any packet drops or flushes.


e) If no packet drops and flushes found in the output of "show interfaces", then capture Ethereal trace for 5-10 minutes while linkflapping is observed and open a Cisco TAC case for further help.

Hope that the above helps when observing the mentioned link flapping issues.

Kind regards,


Samuel.

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Last update:
‎09-02-2010 06:52 PM
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