Motorola MPC8260 - Manual (Page 838)

29-58 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA
Part IV. Communications Processor Module
29.10.2.3.6 ABR Protocol-SpeciÞc TCTE
Figure 29-36 shows the ABR protocol-speciÞc TCTE.
Table 29-27 describes ABR-speciÞc TCTE Þelds.
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Offset + 0x00 ER-TA
Offset + 0x02 CCR-TA
Offset + 0x04 MCR-TA
Offset + 0x06 TUAR Ñ CI-TA NI-TA Ñ CP-TA Ñ CI-VC Ñ
Offset + 0x08 MCR
Offset + 0x0A UNACK
Offset + 0x0C ACR
Offset + 0x0E ACRC Ñ
Offset + 0x10 RM Cell Time Stamp (RCTS)
Offset + 0x12
Offset + 0x14 FRST Ñ CDF COUNT
Offset + 0x16 ICR
Offset + 0x18 CRM
Offset + 0x1A ADTF
Offset + 0x1C ER
Offset + 0x1E ER-BRM
Figure 29-36. ABR Protocol-Specific TCTE
Table 29-27. ABR-Specific TCTE Field Descriptions
Offset Bits Name Description
0x00 Ñ ER-TA Explicit rateÐturn-around cell. Holds the ER of the last received F-RM cell. If another F-RM
cell arrives before the previous F-RM cell was turned around, this Þeld is overwritten by the
new RM cellÕs ER.
0x02 Ñ CCR-TA Current cell rateÐturn-around cell. Holds the CCR of the last received F-RM cell. If another
F-RM cell arrives before the previous F-RM cell was turned around, this Þeld is overwritten
by the new RM cellÕs CCR.
0x04 Ñ MCR-TA Minimum cell rateÐturn-around cell. Holds the MCR of the last received F-RM cell. If
another F-RM cell arrives before the previous F-RM cell is turned around, this Þeld is
overwritten by the new RM cellÕs MCR.
0x06 0 TUAR Turn-around ßag. The CP sets TUAR to indicate that a new F-RM cell was received, which
causes the transmitter to send a B-RM cell whenever the ABR ßow control permits.
Initialize to 0.
1 Ñ Reserved, should be cleared.
2 CI-TA Congestion indicationÐturn-around cell. Holds the CI of the last received F-RM cell. If
another F-RM cell arrives before the previous F-RM cell was turned around, CI-TA is
overwritten by the new RM cellÕs CI.
3 NI-TA No increaseÐturn-around cell. Holds the NI of the last received F-RM cell. If another F-RM
cell arrives before the previous one was turned around, NI-TA is overwritten by the new
RM cellÕs NI.