carrier transitions on PA-E3 7204VXR

[david.ashby]

We are experiencing very intermittent carrier transitions on a PA-E3 interface (G703). We understand this may indicate loss of clocking signal from the line. Is this true? If so how many clock cycles would need to be missed to increment the counter? Our carrier tells us they have no errors corresponding to the problems reported on the router. On some occasions the carrier transitions appear to trigger an interface reset, which then disrupts traffic. Other errors observed on sho int s1/0 are underrun errors at one end of the link and abort errors at the other. Both at very low level of occurrence.

[vijayasankar]

Hi David,

Check the following URL which explains the carrier transition error.

http://www.cisco.com/en/US/tech/tk713/tk628/technologies_tech_note09186a00800a758d.shtml#topic8

Mostly i have faced this error, which is associated with poor physical layer connectivity and clocking problems with telco.

You can have more detailed statistics by using the show controlle e1 slot/port command.

It will always be a tricky to deal with service providers.

It would be better if you request them to perform a BERT /stability test of the link, which will reveal the potential cause of the problem.

HTH

-VJ

[david.ashby]

Thanks for the advice and link.

I've spoken to our carrier's system engineer, and he also suggested end to end BERT test. Only problem with this is negotiating the down time to do it for a long enough period, but it looks like its the only way we'll isolate the problem.