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

Messages in

Messages out

Message Build up

Congestion abatement

Congestion onset

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

Messages in

Messages out

Message Build up

Congestion onset

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

Messages in

Messages out

Messages Build up and then

clear

Congestion onset

Congestion abatement

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

Messages in

Messages out

Message Build up

Congestion Discard