Released
Datasheet
PM73487 QRT
PMC-Sierra, Inc.
PMC-980618
Issue 3
622 Mbps ATM Traffic Management Device
2.5.3 Receive Channel Ring
The list of channels eligible to send a cell to the fabric are kept in per-SC rings. The ring is kept in
external memory and pointers to the previous and current channels for each SC are kept in inter-
nal memory. A channel number is entered into the ring when the first cell for that channel arrives.
While cells for that channel are present in the queuing system, the channel can be removed from
the ring by the dequeue process (if the channel is run-limited because of the resequencing algo-
rithm as explained in “Receive Sequencing Algorithm” on page 34) and sometimes re-added to
the ring by the process that updates the data structures with the results of the last cell time.
Figure 30, Figure 31, Figure 32, and Figure 33 on page 29 show the operation of the receive chan-
nel ring.
Channel_B
Channel_A
Service Class (SC)
Current Channel
Previous
Channel_E
Channel_C
Channel_D
Figure 30. Receive Channel Ring
Channel_B
Service Class (SC)
Current Channel
Previous
Channel_E
Channel_C
Channel_D
Figure 31. Receive Channel Ring after Channel_A Becomes Run-Limited
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PMC [ PMC-SIERRA, INC ]
