27-24
Cisco ME 3800X and 3600X Switch Software Configuration Guide
OL-23400-01
Chapter 27 Configuring QoS
Configuring QoS
Configuring QoS
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Default QoS Configuration, page 27-24
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Configuration Guidelines and Limitations, page 27-24
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Configuring Input Policy Maps, page 27-25
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Configuring Output Policy Maps, page 27-41
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Configuring MPLS and EoMPLS QoS, page 27-53
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Attaching a Service Policy to an Interface or EFP, page 27-56
Default QoS Configuration
There are no policy maps, class maps, table maps, or policers configured. At the egress target, all traffic
goes through a single default queue that is given the full operational bandwidth.
The packets are not modified. The CoS, DSCP, IP precedence, and MPLS EXP values in the packet are
not changed. Traffic is switched in pass-through mode without any rewrites and classified as best effort
without any policing.
Configuration Guidelines and Limitations
The ME 3800X and ME 3600X switches support the same QoS functionality. All switches support a total
of 4,000 QoS instances, where a QoS instance is any target on which a QoS per-hop behavior policy is
attached. A target can be a port, a VLAN class, or an EFP service instance.
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You can configure a maximum of 1024 policy maps.
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You can apply one input policy map and one output policy map to an interface or service instance.
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The maximum number of classification criteria per class map is 64. The maximum number of classes
per policy map is 4000.
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Policy configurations are validated as they are configured. When invalid configurations are detected,
they are rejected. In some cases the configuration cannot be validated until it is associated with an
interface.
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If you modify a feature characteristic on a port or EFP that has a policy map attached and the new
configuration makes the policy map invalid, the attached policy is automatically detached.
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You can attach service policies to switchports, routed ports, or EFPs. However, you cannot attach a
service policy to a physical port that is configured with service instances (EFPs) and you cannot
attach service policies to switch virtual interfaces (SVIs).
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You cannot attach a service policy to an EtherChannel. You can only attach service policies to
individual ports in the port channel. You cannot attach a service policy to an EFP that belongs to a
port channel interface.
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When a configured policer rate, policer burst-size, or queue-rate cannot be achieved in hardware
within 1 percent, the configuration is rejected.
