User guide

Brocade 6910 Ethernet Access Switch Configuration Guide 425

53-1002581-01

Priority Commands (Layer 3 and 4)

• Enter a value pair for the internal per-hop behavior and drop precedence, followed by the

keyword “from” and then up to eight CoS/CFI paired values separated by spaces.

• 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.

• Random Early Detection starts dropping yellow and red packets when the buffer fills up to 16

packets on a port, and then starts dropping any packets regardless of color when the buffer

fills up to 58 packets on a port.

• The specified mapping applies to all interfaces.

Example

Console(config)#interface ethernet 1/5

Console(config-if)#qos map cos-dscp 0 0 from 0 1

Console(config-if)#

qos map dscp-mutation

This command maps DSCP values in incoming packets to per-hop behavior and drop precedence

values for priority processing. Use the no form to restore the default settings.

Syntax

qos map dscp-mutation phb drop-precedence from dscp0 ... dscp7

no qos map dscp-mutation dscp0 ... dscp7

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)

dscp - DSCP value in ingress packets. (Range: 0-63)