Edge-Core ECS4810-12M Layer 2, Руководство по управлению

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C
HAPTER
11
| Class of Service
Layer 3/4 Priority Settings
– 254 –
◆
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.
P
ARAMETERS
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)
Table 18: 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)