Brocade Communications Systems Brocate Ethernet Access Switch 6910 - Manual (Page 849)

Brocade 6910 Ethernet Access Switch Configuration Guide 799
53-1002581-01
Layer 3/4 Priority Settings
38
• If a packet arrives with a 802.1Q header but it is not an IP packet, then the
CoS/CFI-to-PHB/Drop Precedence mapping table is used to generate priority and drop
precedence values for internal processing. Note that priority tags in the original packet are not
modified by this command.
• The internal DSCP consists of three bits for per-hop behavior (PHB) which determines the
queue to which a packet is sent; and two bits for drop precedence (namely color) which is used
by Random Early Detection (RED) to control traffic congestion.
• RED starts dropping yellow and red packets when the buffer fills up to 16 packets on Fast
Ethernet ports and 72 packets on Gigabit Ethernet ports, and then starts dropping any packets
regardless of color when the buffer fills up to 58 packets on Fast Ethernet ports and 80
packets on Gigabit Ethernet ports.
• The specified mapping applies to all interfaces.
Parameters
These parameters are displayed:
• Port – Specifies a port.
• CoS – CoS value in ingress packets. (Range: 0-7)
• CFI – Canonical Format Indicator. Set to this parameter to “0” to indicate that the MAC address
information carried in the frame is in canonical format. (Range: 0-1)
• PHB – Per-hop behavior, or the priority used for this router hop. (Range: 0-7)
• Drop Precedence – Drop precedence used for Random Early Detection in controlling traffic
congestion. (Range: 0 - Green, 3 - Yellow, 1 - Red)
Interface
To map CoS/CFI values to internal PHB/drop precedence:
1. Click Traffic, Priority, CoS to DSCP.
2. Select Configure from the Action list.
3. Select a port.
4. Set the PHB and drop precedence for any of the CoS/CFI combinations.
5. Click Apply.
TABLE 164 Default Mapping of CoS/CFI to Internal PHB/Drop Precedence
CFI
CoS
0 1
0 (0,0) (0,0)
1 (1,0) (1,0)
2 (2,0) (2,0)
3 (3,0) (3,0)
4 (4,0) (4,0)
5 (5,0) (5,0)
6 (6,0) (6,0)
7 (7,0) (7,0)