Brocade Communications Systems Brocate Ethernet Access Switch 6910 - Manual (Page 843)

Brocade 6910 Ethernet Access Switch Configuration Guide 793
53-1002581-01
Layer 2 Queue Settings
38
Mapping CoS Values to Egress Queues
Use the Traffic > Priority > PHB to Queue page to specify the hardware output queues to use based
on the internal per-hop behavior value. (For more information on exact manner in which the ingress
priority tags are mapped to egress queues for internal processing, see
“Mapping CoS Priorities to
Internal DSCP Values” on page 798).
The switch processes Class of Service (CoS) priority tagged traffic by using eight priority queues for
each port, with service schedules based on strict priority, Weighted Round-Robin (WRR), or a
combination of strict and weighted queuing. Up to eight separate traffic priorities are defined in
IEEE 802.1p. Default priority levels are assigned according to recommendations in the IEEE 802.1p
standard as shown in
Table 160 . The following table indicates the default mapping of internal
per-hop behavior to the hardware queues. The actual mapping may differ if the CoS priorities to
internal DSCP values have been modified (
page 798 ).
The priority levels recommended in the IEEE 802.1p standard for various network applications are
shown in
Table 161 . However, priority levels can be mapped to the switch’s output queues in any
way that benefits application traffic for the network.
CLI References
• “qos map phb-queue” on page 427
Command Usage
• Egress packets are placed into the hardware queues according to the mapping defined by this
command.
• The default internal PHB to output queue mapping is shown below.
• The specified mapping applies to all interfaces.
TABLE 160 IEEE 802.1p Egress Queue Priority Mapping
Priority 0 1 2 3 4 5 6 7
Queue 2 0 1 3 4 5 6 7
TABLE 161 CoS Priority Levels
Priority Level Traffic Type
1 Background
2 (Spare)
0 (default) Best Effort
3 Excellent Effort
4 Controlled Load
5 Video, less than 100 milliseconds latency and jitter
6 Voice, less than 10 milliseconds latency and jitter
7 Network Control
TABLE 162 Mapping Internal Per-hop Behavior to Hardware Queues
Per-hop Behavior 0 1 2 3 4 5 6 7
Hardware Queues 2 0 1 3 4 5 6 7