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. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

7206 IOS and T1 Flapping:

I am planning to upgrade my 7206 router, currently I am running 12.2.10a image. I have three T1 8 ports modules, two ISDN modules and one DS3 modules in my router. I have couple of question, 1st if I want to upgrade my IOS image which version is compatible with my router that support all my modules. 2nd I am having issue with T1 line it is flapping, my T1 is spread in all three modules. I have telco test line no problem. Any suggestion what do I check to fix the problem. Or it is a IOS bug, or bad hardware. I will be grateful for any help.



Re: 7206 IOS and T1 Flapping:

For the 1st question on the code upgrade. 12.2.10a has a sw advisory against it and was made unavailable on cisco site for download. It is recent code as well. The advisory doesn't really have any documented issues for the 7200 however (3600 HSSI issue mainly). You may want to look into going to 12.2.12a which is the latest revision of the 12.2 mainline code. I wouldn't recommend going to another 12.2 train code unless you are specifically looking for and need a new feature introduced in that train.

Are all ports in the 3 8 port T1s populated? Are you seeing multiple T1s flapping or just one? Anything showing up the log?

Do a 'show interface (interface)' on the flapping interface and see if you have any input errors or other errors. You may want to clear the counters and repeat this command frequently to get a baseline for how often the errors are increasing. If you're getting errors maybe look at doing a local loopback test to see if it may be the equipment. You could also move the config to another port to see if the problem follows the router interface or the circuit. Try a working good circuit on the flapping interface also. This will require some downtime and reconfiguration but is part of troubleshooting process.

How are the T1 interfaces configured that are flapping?

New Member

Re: 7206 IOS and T1 Flapping:

A "show controller t1 x/x" will show you the stats the telephone company looks at. If there are errors there, i would suggest using a local loopback plug to test the interface. I have seen T1 interfaces on those same cards loop fine in both directions, but still run dirty. An external loopback plug will eliminate any internal hardware issues as would moving the circuit to a different port.