Microsens MS453490M Management Guide User Manual
Page 823
C
HAPTER
35
| Class of Service Commands
Priority Commands (Layer 3 and 4)
– 823 –
D
EFAULT
S
ETTING
.
C
OMMAND
M
ODE
Interface Configuration (Port, Static Aggregation)
C
OMMAND
U
SAGE
◆
The default mapping of CoS to PHB values shown in
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 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 ports 1-24 and 72 packets on ports 25-26, and then
starts dropping any packets regardless of color when the buffer fills up
to 58 packets on ports 1-24 and 80 packets on ports 25-26.
◆
The specified mapping applies to all interfaces.
E
XAMPLE
Console(config)#interface ethernet 1/5
Console(config-if)#qos map cos-dscp 0 0 from 0 1
Console(config-if)#
Table 117: 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)