VSC7440 datasheet(237/444 Pages) MICROSEMI

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Functional Descriptions

VMDS-10492 VSC7440 Datasheet Revision 4.2

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The illustration also shows the two super-priority queues available in all ports. The scheduler hierarchy

configuration must be based on a desired scheme. The hardware default setup is providing a queue per

(source, priority) per egress port. All queues with the same QoS level are arbitrated first, in layer 0.

Figure 61 •

Scheduler Hierarchy (Normal Scheduling Mode)

3.24.5.1 Mapping System

All queues in the system are referred to as a layer 0 SE number and an input number. For example, the

default configuration puts all traffic for port 0 from source 7 in priority 0 into the queue (0,7); SE number 0,

input 7. When the forwarder requests a frame to be added to a queue, the queue group—all classified

priorities, the source port, and the destination port—are used to find the SE and input on it, through some

configurable mapping tables. There are three basic hierarchy types, and the first part of the mapping

procedure is to find the hierarchy type in QFWD::QMAP_PORT_MODE. The mode is found for frames

with classified qgrp = 0 in the QMAP_MODE_NONSERVICE field and in QMAP_MODE_SERVICE for

qgrp >0. Note that service and non-service mappings can be combined at the higher layers, in order to

combine the two basic types of traffic in the application. An overview of the queue mapping tables is

shown in the following illustration. The drop statistics mode is also found by looking up information in

these tables. For more information, see Statistics, page 230.

src 1, iprio 0

src 14, iprio 0

src 0, iprio 1

src 1, iprio 1

src 14, iprio 1

src 0, iprio 7

src 1, iprio 7

src 14, iprio 7

Scheduler

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