Chapter 9
| Class of Service
Layer 3/4 Priority Settings
– 224 –
Mapping CoS
Priorities to Internal
DSCP Values
Use the Traffic > Priority > CoS to DSCP page to maps CoS/CFI values in incoming
packets to per-hop behavior and drop precedence values for priority processing.
Command Usage
◆ The default mapping of CoS to PHB values is shown in Table 17 on page 224.
◆ Enter up to eight CoS/CFI paired values, per-hop behavior and drop
precedence.
◆ 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.
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 in controlling traffic congestion.
(Range: 0 - Green, 3 - Yellow, 1 - Red)
Table 17: 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)
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