Qos Configuration; Enhanced Transmission Selection; Priority-Based Flow Control - Brocade Communications Systems Brocade BladeSystem 4/24 User Manual

QoS configuration

QoS configuration involves configuring packet classification, mapping the priority and traffic class,
controlling congestion, and scheduling. The configuration of these QoS entities consist of CEE Map
and Traffic Class Map configuration.
In a Converged Enhanced Ethernet (CEE) configuration, Enhanced Transmission Selection (ETS)
and Priority-based flow control (PFC) are configured by utilizing a priority table, a priority group
table, and a priority traffic table. The Traffic Class Map is the mapping of user priority to traffic
class.

Enhanced Transmission Selection

Enhanced Transmission Selection (ETS) allows lower priority traffic classes to use available
bandwidth not being used by higher priority traffic classes and maximizes the use of available
bandwidth.

Priority-based flow control

Priority based flow control (PFC) is an enhancement to the existing pause mechanism in Ethernet.
PFC creates eight separate virtual links on the physical link and allows any of these links to be
paused and restarted independently, enabling the network to create a no-drop class of service for
an individual virtual link.
Table 23
scenario.
TABLE 23
Priority group ID
DCFM Professional Plus User Manual
53-1001774-01
shows examples of how priority grouping might be allocated in a 15-priority group
Bandwidth (%)
0
1
2
3
4
5
6
7
15.0-15.7
No bandwidth % configuration
55
25
0
0
5
0
15
0
Strict priority
allowed
Priority flow control
on
on
off
off
off
off
on
off
on
15
373