Configuring Service Parameter Allocation Rule - H3C S9500 Series Operating Manual

Operation Manual – QoS
H3C S9500 Series Routing Switches
Table 1-1 QoS terms
CoS
Service parameters
Drop-precedence
Conform-Level

1.2.1 Configuring Service Parameter Allocation Rule

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-to-local
precedence mapping table and the CoS-to-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 to allocate a local
precedence for the packet, it uses the local precedence of the receiving port as the CoS
value to search the CoS-to-local precedence mapping table for the local precedence of
the packet. Then the switch inversely searches the default CoS-to-local precedence
Term
It has the same meaning as 802.1p priority. Both refer to the
priority at packet header, with the value ranging from 0 to 7.
Switch allocates a set of parameters, which are used in
achieving QoS functions, upon receiving a packet. Four
items are included: 802.1p priority, DSCP priority, local
precedence, and drop precedence.
One of service parameters, ranging from 0 to 2. Drop
precedence is allocated when the switch receives the packet
and may be when the packet is processed. Allocating drop
precedence to the packet is also called coloring the packet:
the packet with drop precedence 2 as red, that with drop
precedence 1 as yellow and that with drop precedence 0 as
green. Drop precedence is referred to when switch needs to
drop packets in its congestion.
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 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.
Remarks
1-7
Chapter 1 QoS Configuration