Alcatel-Lucent 6850-48 网络指南

QoS Ports and Queues

Configuring QoS

page 40-24

OmniSwitch AOS Release 6 Network Configuration Guide

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 

 command) with either of the 

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

• Port settings configured through the 

 command.

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 band-
width. 

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.

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 the servicing mode 
that is active for the egress port. See 

 for more 

information.

The egress priority of a packet is determined as follows:

1 If a packet matches a QoS policy rule that sets a priority value, the egress priority for the packet is set 
using the value specified in the rule. 

2 If a packet ingressing on a trusted port does not match any QoS policy rule that sets the priority, then 
the egress priority for the packet is set using the existing DSCP value (IP packets), the existing 802.1p 
value (non-IP packets), or the default classification priority value for the port. See 

3 The egress priority for a packet ingressing on a VLAN Stacking port (a trusted port) is set using the 
existing 802.1p value or configured through an associated VLAN Stacking service.

4 If a packet ingressing on an untrusted port does not match any QoS rule that sets the priority, then the 
egress priority for the packet is set using the default 802.1p value configured for the port on which the 
packet was received. See 

 

for more information.

5 Note that the 802.1p bit for tagged packets ingressing on untrusted ports is set with the default 802.1p 
value, which is configured using the 

 command. If the packet is untagged, 

however, then the DSCP bit is set with the default DSCP value, which is configured using the 

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