Motorola MPC8260 - Manual (Page 802)

29-22 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA
Part IV. Communications Processor Module
3. The CCR and MCR Þelds are taken from the F-RM and is not changed.
4. The CI bit of the B-RM cell is set if the previous data cell arrived with EFCI = 1
(congestion bit in the ATM cell header).
5. The ER Þeld of the turn around B-RM cells is limited by TCTE[ER-BRM].
6. If a F-RM cell arrives before the previous F-RM cell was turned around (for the same
connection), the new RM cell overwrites the old RM cell.
29.5.1.3 ABR Flowcharts
The MPC8260Õs ABR transmit and receive flow control is described in the following
ßowcharts. See Figure 29-11, Figure 29-12, Figure 29-13, and Figure 29-14.
Figure 29-11. ABR Transmit Flow
Start Channel Tx
ACR < TCR
Send RM (DIR = forward, CCR = ACR, ER = PCR, CI = NI = 0, CLP =1)
Schedule: Time_to_send = now+1/TCR
ACR is low sent only
EXIT
RM/DATA In Rate Cell Tx
ACR>=TCR
out-of-rate cells at TCR
Source End-Sys 9
Yes
No