1. Congestion onset and abatement Indications of congestion onset and congestion abatement are provided to the user The buffer has a congestion onset threshold and a congestion abatement threshold

2. Congestion onset Congestion onset indication is generated when the congestion onset threshold is reached From this point the buffer is considered to be in congestion until abatement occurs

3. Congestion abatement Congestion abatement is indicated when the number of messages allocated drops back below the abatement threshold An abatement indication will only be generated when the buffer is in a congested state No further abatement indications will be generated unless congestion onset is reached The congestion state has cleared

4. Congestion discard The signalling link and board congestion buffers have a discard threshold When the discard threshold is reached addition messages sent to the buffer are discarded An indication of message discard is sent to the user