Serial Interface keeps going up and down

[muca]

I have a 2600 XM connected to 8 remote locations through frame-relay and using isdn as a backup solution.

Sometimes the serial interface keeps going up and down. So the isdn does not work.

We have to reset the DCE (ISP's modem) and the frame-relay works again.

The ISP changed the DCE 2 times but sometimes I still get the problem.

Has anybody faced such problem?

The ISP says the problem is with the router.

Can it be a router problem? Hardware?

Thanks

[sundar.palaniappan]

If the CSU/DSU is proved good, then it has to be the either the v.35 cable or the router interface.

Try swapping the v.35 cable (cable btw the router to the CSU) and move the cable over to another Serial interface, if you have one available to isolate the problem.

HTH,

Sundar