Users Guide

Marking Traffic
After you classify the ingress traffic, you can set the value or change an existing value (remarking) for CoS or DSCP. Marking
sets the IP precedence or IP DSCP value for traffic at ingress. The switch then uses the new marking to process the traffic.
Traffic class IDs identify the traffic flow when the traffic reaches egress for queue scheduling.
Mark traffic
1. Create a QoS type class-map to match the traffic flow.
OS10(config)# class-map cmap-cos3
OS10(config-cmap-qos)# match cos 3
2. Create a QoS type policy-map to mark it with a traffic class ID and assign it to the CoS flow.
OS10(config)# policy-map cos3-TC3
OS10(config-pmap-qos)# class cmap-cos3
OS10(config-pmap-c-qos)# set qos-group 3
Queuing
The egress bandwidth of a port is logically divided into eight queues (0 to 7).
Data that is classified at ingress into the different traffic classes is assigned to the respective queue by default. You can
override the default mapping. Depending on the priority that is configured for the traffic, you can assign the traffic flow to
different queues at egress. Queues with higher priority are serviced first before moving on to queues with lower priority.
By default, the value of traffic class ID for all the traffic is 0.
You can set the traffic class ID for a flow by enabling trust or by classifying ingress traffic and marking it with a traffic class ID
using a policy map (qos-map). The order of precedence for a qos-map is:
1. Interface-level map
2. System-qos-level map
3. Default map
Table 139. Default mapping of traffic class ID to queue
Traffic class ID (802.1p CoS value) Queue ID
0 0
1 1
2 2
3 3
4 4
5 5
6 6
7 7
User–defined QoS map
You can override the default mapping by creating a QoS map.
Configure user–defined QoS map
1. Create a QoS map.
OS10(config)# qos-map traffic-class tc-q-map
1528
Quality of service