Motorola PowerQUICC II MPC8280 Series Reference Manual page 1222

IMA Microcode Architecture
APC
SAR
Tx Queue
TRL Tx
34.3.2.1 TRL Operation
A request from the TRL PHY is used to trigger a complete round-robin process of cell
scheduling and distribution, distributing one cell for each of the transmit queues of the N
links in the IMA group. For each link, the microcode will:
1. Determine whether an ICP cell or a data/filler cell should be sent for the link:
— If data/filler, determine whether link is in 'active' or 'filler-only' mode
— If active, run the APC scheduling algorithm to find the next scheduled ATM
channel
2. Distribute either:
— An ICP cell
— A filler cell (if 'filler-only' or 'active' with nothing scheduled in the APC)
— A data cell (if a channel is scheduled in the APC, performing the appropriate
segmentation task for the scheduled ATM channel, as determined by the
channel's AAL type)
The cells are distributed by writing the complete cells into circular transmit queues
provided per link. These transmit queues function as 'jitter buffers', as they are used to
34-12
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N times
Tx Queue
non-TRL Tx
UTOPIA Multi-PHY
Figure 34-5. IMA Transmit Task Interaction
MPC8280 PowerQUICC II Family Reference Manual
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TRL Tx Task
Tx Queue Tx Queue
Task
Jitter
Buffers
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