Converged Enhanced Ethernet Administrator's Guide v6.4.0 (53-1001761-01, June 2010)

96 Converged Enhanced Ethernet Administrator’s Guide
53-1001761-01
Queueing
9
DRAFT: BROCADE CONFIDENTIAL
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.
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 17 Default user priority for unicast traffic class mapping
User priority Traffic class
01
10
22
33
44
55
66
77
TABLE 18 Default user priority for multicast traffic class mapping
User Priority Traffic class
00
10
21
31
42
52
63
73