Brocade Communications Systems 53-1001761-01 manual Unicast traffic, Multicast traffic

9 Queueing

The traffic class mapping stage provides some flexibility in queue selection:

•The mapping may be many-to-one, such as mapping one byte user priority (256 values) to eight traffic classes.

•There may be a non-linear ordering between the user priorities and traffic classes.

Unicast traffic

Table 17 presents the Layer 2 default traffic class mapping supported for a COS-based user priority to conform to 802.1Q default mapping.

TABLE 17	Default user priority for unicast traffic class mapping
User priority	Traffic class
0	1
1	0
2	2
3	3
4	4
5	5
6	6
7	7

You are allowed to override these default traffic class mappings per port. Once the traffic class mapping has been resolved it is applied consistently across any queueing incurred on the ingress and the egress ports.

Multicast traffic

The Brocade 8000 supports four multicast traffic classes for isolation and to control servicing for different priorities of application data. Traffic classes are numbered from 0 through 3, with higher values designating higher priority. The traffic class mapping stage provides some flexibility in queue selection.

Table 18 presents the Layer 2 default traffic class mapping supported for a COS-based user priority to conform to 802.1Q default mapping.

TABLE 18	Default user priority for multicast traffic class mapping
User Priority	Traffic class
0	0
1	0
2	1
3	1
4	2
5	2
6	3
7	3

96	Converged Enhanced Ethernet Administrator’s Guide
	53-1001761-01