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Configuring QoS QoS Ports and Queues

OmniSwitch 6800/6850/9000 Network Configuration Guide June 2006 page 26-19

QoS Ports and Queues

Queue parameters may be modified on a port basis. When a flow coming into the switch matches a policy,

it is queued based on:

• Parameters given in the policy action (specified by the policy action command) with either of the

following keywords: priority, maximum bandwidth, or maximum depth.

• Port settings configured through the qos port command.

Shared Queues

Eight priority queues are available at startup for each port. Flows always share queues; however, when a

shared action is specified in policies, the policies will use the same values to implement maximum and

minimum bandwidth.

Note that the OmniSwitch 6800 also has eight priority queues per port but that two of these queues are

reserved for internal use and are not available

Prioritizing and Queue Mapping

QoS prioritizes packets by placing them in a higher priority egress queue. As previously mentioned, there

are eight egress queues available for each port. In addition, there are different queuing algorithms avail-

able for egressing packets of different priorities. The algorithm used is determined by which servicing

mode is active for the egress port. See “Configuring the Servicing Mode for a Port” on page 26-21 for

more information.

The egress priority of a packet is determined using one of the following methods:

1 If a packet matches a QoS policy rule that specifies a priority value, the egress priority for the packet is

set using the value contained in the rule.

2 If a packet does not match any QoS policy rules and is received on a trusted port, the egress priority for

the packet is set using the DSCP value (IP packets) or the 802.1p value (non-IP packets). See “Configur-

ing Trusted Ports” on page 26-23 for more information.

3 If a packet does not match any QoS policy rules and is received on an untrusted port, the egress prior-

ity for the packet is set using the default 802.1p value configured for the port on which the packet was

received. See “Trusted and Untrusted Ports” on page 26-22 for more information.

Use the following table to see how packets are directed to the appropriate queues:

Priority to Queue Mapping Table

802.1p ToS/DSCP

Rule(action)

Priority

OS6850/9000

Queue

OS6800

Queue

0 000xxx 0 0 0

001xxx 1 1 0

2 010xxx 2 2 1

011xxx 3 3 2

100xxx 4 4 3

101xxx 5 5 4

1 2 ... 520 521 522 523 524 525 526 527 528 529 530 ... 701 702

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Alcatel 9000 Guía de usuario Pagina 525

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