The add queues are not part of the MAC, they are implemented by the client. The
MAC indicates which frames can be forwarded by controlling the send signals. Accepted
client traffic is placed into a stage queue, one frame at a time. The stage queue is a logical
construct that might or might not correspond to any physical structure.
Frames added by the MAC control sublayer are shaped by the MAC control shaper that
limits the amount of control traffic added by the MAC. Control frames are usually labeled
Figure 12.15 Data path??”Single transit path
Client
MAC
control
sublayer
MAC
medium
access
control
Checker PTQ
Idle shl
addMac shM Fairness
control
Send A Send B Send C
To other
attachment
Rate
monitors
shA0
shB shF
shD
Stage
addA
addB
addC
Resilient Packet Ring (RPR) 349
subclassA0 and also shaped by the subclassA0 shaper, but can be labeled classB or
classC (e.g., echo request and response) and directed to the classB shaper or the fairness
eligible shaper, respectively, as illustrated by the dotted lines in Figures 12.15
and 12.16. Shaping by the MAC control shaper is applied first and in addition to the
other shapers.
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