Data Center Fabric Manager Professional User Manual v10.3.X (53-1001355-01, November 2009)

DCFM Professional User Manual 283
53-1001355-01
Priority-based flow control
11
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 31 shows examples of how priority grouping might be allocated in a 15-priority group
scenario.
Creating a CEE map
When you create a CEE map, each of the Class of Service (CoS) options (0-7) must be mapped to at
least one of the Priority Group IDs (0-7). All QoS, CEE map, and Traffic map configurations apply to
all ports in a LAG.
There can be, at the most, 16 entries in the Priority Group table. Eight of the entries are Strict
Priority entries with a Priority Group ID of 15.0 to 15.7 and eight are user-definable entries with a
Priority Group ID of 0-7.
See Table 31 for an example of priority group configuration.
1. Select Configure > CEE Switch > CEE from the menu bar.
The CEE Configuration dialog box displays, showing the status of all CEE-related hardware and
functions.
2. Select a switch, and click Edit.
TABLE 31 Priority table allocation example
Priority group ID Bandwidth (%) Priority flow control
055 on
125 on
20 off
30 off
45 off
50 off
615 on
70 off
15.0-15.7 Strict priority
No bandwidth % configuration
allowed
on