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Configuring QoS
QoS Treatment for Performance-Monitoring Protocols
Queuing
The CFM traffic (including IP SLAs using CFM probes) is queued according to its CoS value and the output policy map
configured on the egress port, similar to normal traffic. This feature cannot change this behavior.
IP traffic (including IP SLA and TWAMP probes) is queued according to the markings specified in the cpu traffic qos
global configuration command and the output policy map on the egress port. If this command is not configured, all IP
traffic is statically mapped to a queue on the egress port.
QoS Marking for CPU-Generated Traffic
You can use QoS marking to set or modify the attributes of traffic from the CPU. The QoS marking action can cause the
CoS, DSCP, or IP precedence bits in the packet to be rewritten or left unchanged. QoS uses packet markings to identify
certain traffic types and how to treat them on the local switch and the network.
You can also use marking to assign traffic to a QoS group within the switch. This QoS group is an internal label that does
not modify the packet, but it can be used to identify the traffic type when configuring egress queuing on the network port.
You can specify and mark traffic CPU-generated traffic by using these global configuration commands:
cpu traffic qos cos {cos_value | cos [table-map table-map-name] | dscp [table-map table-map-name]| precedence
[table-map table-map-name]}
cpu traffic qos dscp {dscp_value | cos [table-map table-map-name] | dscp [table-map table-map-name] |
precedence [table-map table-map-name]}
cpu traffic qos precedence {precedence_value | cos [table-map table-map-name] | dscp [table-map
table-map-name] | precedence [table-map table-map-name]}
cpu traffic qos qos-group value
You can mark CoS, IP-DSCP, IP precedence, and QoS group by configuring an explicit value or by using the table-map
keyword. Table maps list specific traffic attributes and map (or convert) them to another attribute. A table map establishes
a to-from relationship for the attribute and defines the change to be made:
Marking CoS by using the CoS, or the IP-DSCP, or the IP precedence of IP CPU-packets
Marking CoS by using the CoS of non-IP CPU-packets.
Marking IP DSCP by using the CoS, or the IP-DSCP, or the IP precedence of the CPU-packet
Marking IP precedence by using the CoS, or the IP-DSCP, or the IP precedence of the CPU-packet
You can configure either IP-DSCP or IP precedence marking.
You can also simultaneously configure marking actions to modify CoS, IP-DSCP or IP precedence, and QoS group.
The cpu traffic qos
command specifies the traffic to which it applies: all CPU traffic, only CPU IP traffic, or only CPU
non-IP traffic. All other traffic retains its QoS markings. This feature does not affect CFM traffic (including Layer 2 IP SLA
probes using CFM).
Note: The switch provides the ability to mark CoS, IP-DSCP and IP precedence of CPU-generated traffic by using table
maps.
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