3101—There has occured a failure in the SAAL stack, which transfers
signalling data. The signalling message transfer via signalling
link in question is not possible and signalling messages which have
already been sent to the signalling link might have been lost.
The system has changed the state of the signalling link to
OUT-OF-SERVICE and it is not possible to perform changeover to
another, replacing link. The system sets automatically the defected
signalling link back to the IN-SERVICE state when the SAAL
resources are in order again.
There is also a possibility that defective module. try to replace the transmission module. Check also the cross connection betwwen RNC and aggregator if properly defined.