The implementation of network egress scheduling on the cards and ports listed in Table: Scheduling Modes Supported by Adapter Cards and Ports at Network Egress under ‟4-Priority” is very similar to the scheduling mechanisms used for adapter cards that are configured for access ingress traffic. 4-priority scheduling is a combination of queue-type scheduling (Expedited vs. Best-effort scheduling) and profiled scheduling (rate-based 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)
Packets less than or up to the CIR are scheduled as in-profile. Packets that arrive at rates greater than the CIR, but less than the PIR, are scheduled as out-of-profile. In-profile traffic is exhaustively transmitted from the queues before out-of-profile traffic is transmitted. That is, all of the in-profile packets must be transmitted before any out-of-profile packets are transmitted. In addition, Expedited queues are always scheduled prior to Best Effort queues.
The default configuration of scheduling CoS queues provides a logical and consistent means to manage the traffic priorities. The default configuration is as follows:
CoS-8 to CoS-5 Expedited in-profile
CoS-4 to CoS-1 Best Effort in-profile
CoS-8 to CoS-5 Expedited out-of-profile
CoS-4 to CoS-1 Best Effort out-of-profile
Default configuration means that the queues are configured according to the tables and defaults described in this guide. Customers can configure the queues differently.
The order shown below is maintained when scheduling the traffic on the adapter card’s network ports. A strict priority is applied between the four schedulers, and all four schedulers are exhaustive:
Expedited in-profile traffic
Best Effort in-profile traffic
Expedited out-of-profile traffic
Best Effort out-of-profile traffic