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QoS Prioritization of Traffic on SecureStacks without Policy

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Article ID: 11785

SecureStack B3, B2, A2

Quality of Service (QoS) on the SecureStacks is typically implemented using Policy Manager's (5461) rich capabilities which tie to the SecureStack's 'set policy...' and 'set cos...' command sets. The SecureStack C3 and C2 support these command sets by default, the B3 and B2 require licensing (5781) to unlock them, and the A2 does not support them.

In the absence of Policy, alternative functionality is offered in the DiffServ command set (5848), which though useful for many QoS purposes is not able to directly assign Layer 2 prioritization of incoming traffic which will survive more than the local switch-hop.

The remaining functionality which is unconditionally available in all of the SecureStack products is the ability to use a "Port Priority" - analogous to the "Port VLAN" in terms of VLAN assignment - to assign 802.1p Prioritization to incoming VLAN-untagged traffic. The priority value can affect transmit queue assignment, and the value is retained in any 802.1Q VLAN tagging that may be applied to this traffic on the next or subsequent switch-hops.

For example, here is a management session in which a priority of 5 is assigned to all VLAN-untagged traffic ingressing from a user or users on port ge.1.2. Other traffic would presumably retain the default priority of 0.
B2(su)->set port priority ge.1.2 5
B2(su)->show port priority
ge.1.1 is set to 0
ge.1.2 is set to 5
ge.1.3 is set to 0
. . .
ge.1.24 is set to 0
lag.0.1 is set to 0
. . .
lag.0.6 is set to 0

[/code]By default, on the egressing ports priority 5 traffic is moved to transmit queue 4, and priority 0 traffic is moved to transmit queue 1, for Strict Priority egress (7584). The higher-numbered queues having transmit priority over the lower-numbered queues, prioritized traffic will transmit before other traffic.

See also: 11695.

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