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Chapter 37: Class of Service Commands
Priority Commands (Layer 3 and 4)
qos map
dscp-mutation
C
U
OMMAND
SAGE
The default mapping of CoS to PHB values shown in
•
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 by Random Early
Detection (RED) to control traffic congestion.
The specified mapping applies to all interfaces.
•
E
XAMPLE
Console(config)#qos map cos-dscp 0 0 from 0 1
Console(config)#
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.
S
YNTAX
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 in controlling traffic
congestion.
(Range: 0 - Green, 3 - Yellow, 1 - Red)
dscp - DSCP value in ingress packets. (Range: 0-63)
.
D
S
EFAULT
ETTING
Table 37-5: Default Mapping of DSCP Values to Internal PHB/Drop Values
ingress-
0
1
dscp1
ingress-
dscp10
0
0,0
0,1
1
1,0
1,3
– 1127 –
2
3
4
5
0,0
0,3
0,0
0,1
1,0
1,1
1,0
1,3
Table 37-4
is based
6
7
8
9
0,0
0,3
1,0
1,1
2,0
2,1
2,0
2,3
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