ECS4660-28F_Management Guide-R03

C HAPTER 41 | Class of Service Commands
Priority Commands (Layer 3 and 4)
– 1394 –
COMMAND USAGE
◆ The default mapping of CoS to PHB values shown in Table 175 is based
on the recommended settings in IEEE 802.1p for mapping CoS values
to output queues.
◆ 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 to control traffic
congestion.
◆ 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 default-
drop-precedence
This command maps the internal per-hop behavior (based on packet
priority) to a default drop precedence for internal processing of untagged
packets. Use the no form to restore the default settings.
SYNTAX
qos map default-drop-precedence drop-precedence from phb0 ...
phb7
no map default-drop-precedence phb0 ... phb7
drop-precedence - Drop precedence used for controlling traffic
congestion.
(Range: 0 - Green, 3 - Yellow, 1 - Red)
phb - Per-hop behavior, or the priority used for this router hop.
(Range: 0-7)
DEFAULT SETTING.
Table 176: Mapping Per-hop Behavior to Drop Precedence
Per-hop Behavior 0 1 2 3 4 5 6 7
Drop Precedence 0 0 0 0 0 0 0 0