The adapter cards listed in Table: Scheduling Modes Supported by Adapter Cards and Ports at Network Ingress under ‟4-Priority” can receive network ingress traffic. One or more ports on the card is configured for PPP/MLPPP for this purpose.
The implementation of network ingress scheduling on the cards listed in Table: Scheduling Modes Supported by Adapter Cards and Ports at Network Ingress under ‟4-Priority” is very similar to the scheduling mechanisms used for adapter cards that are configured for access ingress traffic. That is, 4-priority scheduling is used (queue-type scheduling combined with profiled scheduling).
The encapsulation type must be ppp-auto for PPP/MLPPP bundles on the following:
T1/E1 ports on the 7705 SAR-A
T1/E1 ports on the 7705 SAR-M
T1/E1 ports on the 7705 SAR-X
16-port T1/E1 ASAP Adapter card
32-port T1/E1 ASAP Adapter card
2-port OC3/STM1 Channelized Adapter card
4-port OC3/STM1 / 1-port OC12/STM4 Adapter card
T1/E1 ports on the 4-port T1/E1 and RS-232 Combination module (on 7705 SAR-H)
The adapter cards provide sets of eight queues for incoming traffic: 7 sets of queues for the 7705 SAR-8 Shelf V2 and 17 sets of queues for the 7705 SAR-18. Each set of queues is specific to a destination adapter card. For the 7705 SAR-8 Shelf V2 and 7705 SAR-18 (respectively), 6 and 16 sets of queues are automatically created for each access egress adapter card, plus 1 set of queues for multicast traffic.
There is one additional set of queues for slow-path (control) traffic destined for the CSMs.
The individual queues within each set of queues provide buffer space for traffic isolation based on the CoS values being applied (from the received EXP bits).
All of the network ingress ports of the adapter card share the same sets of queues, which are created automatically.
Once the packets received from the network are mapped to queues, four access ingress-like queue-type and profile (rate-based) schedulers per destination card service the queues in strict priority. The following queue-type and profiled schedulers service the queues in the order listed.
Expedited in-profile scheduler
Best Effort in-profile scheduler
Expedited out-of-profile scheduler
Best Effort out-of-profile scheduler
To complete the operation, user-configurable shapers send the traffic into the fabric. See Configurable Ingress Shaping to Fabric (Access and Network) for details. Throughout this operation, each packet retains its individual CoS value.