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
Congestion
onset
Congestion
abatement
Messages
out
Message
Build up
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
Congestion
onset
Message
Build up
Messages
out
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
Congestion
onset
Congestion
abatement
Messages
out
Messages
Build up
and then
clear
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
Congestion
Discard
Message
Build up
Messages
out