The customer has two routers interconnected thru a SDH network and an ATM network. In the SDH section they are using Metro 500 equipments and a N64 Board. For more information see the attached.
They are using C2900 routers in both ends.
The Metro 500 and the N64 boards doesn't have any alarms, but the Frame Relay protocol in the Router connected to the Metro 500 is in Down state.
We have to change the configuration of the N64 board and set the Clock Sampling Mode in [Configuration -Serial port management] from Triggered by Rising Edge to Triggered by Falling Edge.
We use loopbacks to determine the location of the fault and the service works Ok until the N64 board, so, the problem was the interconnection between the N64 DDN-1 port and the Router.