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QoS Ports and Queues Configuring QoS
page 24-20 OmniSwitch 6600 Family Network Configuration Guide April 2006
QoS Ports and Queues
Queue parameters may be modified on a port basis. Four default queues are created for each port on the
switch at start up.
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 or maximum bandwidth).
• Port settings configured through the qos port command.
Shared Queues
On the OmniSwitch 6600, flows always share queues. Four queues are available at startup for each port.
Trusted and Untrusted Ports
By default switch ports are not trusted; that is, they do not recognize 802.1p or ToS/DSCP settings in
packets of incoming traffic. If a port is not trusted, the switch sets any 802.1p or ToS/DSCP to zero in
incoming packets.
Fixed ports that are configured for 802.1Q are always trusted, regardless of QoS settings. They cannot be
configured as untrusted. For more information about configuring 802.1Q for fixed ports, see Chapter 11,
“Configuring 802.1Q.”
Mobile ports are also always trusted; however, mobile ports may or may not accept Q-tagged traffic.
Note About Mobile Ports. Mobile ports cannot be Q-tagged like fixed ports; however, a mobile port will
join a tagged VLAN if tagged traffic for that VLAN comes in on the mobile port and the vlan mobile-tag
command is enabled for that VLAN. For more information about enabling this command, see Chapter 4,
“Configuring VLANs.”
Ports must be both trusted and configured for 802.1Q traffic in order to accept 802.1p traffic.
The following applies to ports that are trusted (for 802.1p traffic, the ports must also be able to accept
802.1Q packets):
• The 802.1p or ToS/DSCP value is preserved.
• If the incoming 802.1p or ToS/DSCP flow does not match a policy, the switch places the flow into a
default queue and prioritizes the flow based on the 802.1p or ToS/DSCP value in the flow.
• If the incoming 802.1p or ToS/DSCP flow matches a policy, the switch queues the flow based on the
policy action.
The switch may be set globally so that all ports are trusted. Individual ports may be configured to override
the global setting.
Configuring Trusted Ports
By default, all ports (except 802.1Q-tagged ports and mobile ports) are untrusted. The trust setting may be
configured globally on the switch, or on a per-port basis.