Schedulers; Port Scheduler Policies On 7210 Sas-D, E; Scheduler Modes; Table 30: Minimum And Maximum Bandwidth Meters Example - Alcatel-Lucent 7210 SAS Series Quality Of Service Manual

Schedulers

Schedulers

Port Scheduler Policies on 7210 SAS-D, E

Port scheduler policies control the traffic behavior on a per-port basis. Associated with each egress
port is a set of eight class of service (CoS) queues and a default port-scheduler-policy named
"default". This default policy makes the port to behave in strict mode. The default policy cannot be
modified. The user can attach another policy to the port to change its scheduling behavior. The
scheduler that provides the arbitration across the eight CoS queues is a scheduler that is configured
in a variety of modes. A major aspect of the arbitration mechanism is the ability to provide
minimum and maximum bandwidth guarantees. This is accomplished by tightly integrating a
network queue and access egress policies into the scheduler. After the packets are mapped into a
COS queue, they are forwarded/conditioned using one of these schedulers (such as Strict Priority
(SP), Round-Robin (RR), Weighted Round-Robin (WRR), Weighted Deficit Round-Robin
(WDRR), (WRR+SP, WDRR+SP). The traffic shaping aspect is tightly integrated with the
scheduler.

Scheduler Modes

The scheduling modes interact with the minimum and maximum bandwidth CoS queue and
maximum bandwidth egress port shaping specifications. Each egress port may be configured to
have a specific scheduling mode. The scheduler first services the queues to meet their CIR and
then services the queues to meet the PIR. There are five possibilities as follows:
•
QoS Queue Name Minimum Bandwidth Maximum Bandwidth

Table 30: Minimum and Maximum Bandwidth Meters Example

Meters
7
6
5
4
3
Page 76 7210 SAS D, E, K OS Quality of Service Guide
Strict priority scheduling across CoS queues — The strict priority scheduler provides strict
priority access to the egress port across the CoS queue from highest CoS queue index (7)
to the lowest (0). The purpose of the strict priority scheduler is to provide lower latency
service to the higher CoS classes of traffic. In this mode, the scheduler services the queues
in order of their prority in both the CIR and PIR loop.
Minimum
10 Mbps
10 Mbps
50 Mbps
50 Mbps
50 Mbps
Maximum
1 Gbps
1 Gbps
1 Gbps
1 Gbps
1 Gbps