3Com 8807 Configuration Manual page 189

Configuring Service
Parameter Allocation
Rule
n
Table 158 QoS terms
Term Description
The result calculated from the user-defined CIR, CBS, EBS, PIR and actual
traffic when the switch runs traffic policing, in the range of 0 to 2. The
parameter is used to select the remark service parameters, such as
remark-cos and remark-drop, in traffic policing by means of the
traffic-limit command. The packets with different conform-levels query
different mapping tables. The conform-level of the packets whose traffic
Conform-Level
is smaller than cir is 0, the conform-level of the packets whose traffic is
bigger than cir and smaller than pir is 1, and the conform-level of the
packets whose traffic is bigger than pir is 2.It is also involved in the DSCP
+ Conform level -> Service parameter mapping table which is used in
re-allocating service parameters to a packet with the traffic-priority
command. Then Conform-Level must be 0.
QoS is based on service parameters, a set of parameters for a packet, including
802.1p priority (CoS priority), DSCP priority, EXP priority, local precedence and
drop precedence.
After receiving a packet, the switch allocates a set of service parameters to it
according to a specific rule. The switch first gets its local precedence and drop
precedence according to the packet 802.1p priority value, by searching in the CoS
-> Local-precedence mapping table and the CoS -> Drop-precedence mapping
table. Default values are available for the two mapping tables, but you can also
configure the mapping tables according to your needs. If the switch fails in
allocating local precedence for the packet, it configures the local precedence of
the packet to be the precedence of the port that receives this packet. After
obtaining the packet CoS value by inverse-searching the CoS -> Local-precedence
mapping table, the switch then gets its drop precedence from the CoS ->
Drop-precedence mapping table.
If a port is not configured by means of the priority command (namely, the default
priority 0 is used), all tagged packets through this port will not be mapped to the
local precedence according to the 802.1p priority in the tag;
When the priority command is used on the port and the parameter of the
command is not 0, or when the traffic-priority command is used to mark the
priority of the packet, all the tagged packets through the port will be mapped to
the local precedence according to the 802.1p priority in the Tag.
Configuring mapping table
Perform the following configurations in system view.
Table 159 Configure mapping tables
Operation
Configure the CoS -> Drop-precedence
mapping table
Restore the default values of CoS ->
Drop-precedence mapping table
QoS Configuration
Command
qos cos-drop-precedence-map
cos0-map-drop-prec cos1-map-drop-prec
cos2-map-drop-prec cos3-map-drop-prec
cos4-map-drop-prec cos5-map-drop-prec
cos6-map-drop-prec cos7-map-drop-prec
undo qos cos-drop-precedence-map
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