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Cisco7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
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Chapter42 Con figuring PFC QoS
Understanding How PFCQoS Works
The PFC2 supports only ingress PFC QoS, which includes ingress policing. The PFC3 supports both
ingress and egress PFC QoS, which includes ingress and egress policing. Traffic shaping is supported on
some WAN modules. For more information about traffic shaping on the OSM and FlexWAN modules,
refer to the OSM and FlexWAN documentation at this location:
http://www.cisco.com/univercd/cc/td/doc/product/core/cis7600/cfgnotes/index.htm
Note Policers can act on ingress traffic per-port or per-VLAN. With a PFC3, for egress traffic, the policers can
act per-VLAN only.
You can create policers to do the following:
•Mark traffic
•Limit bandwidth utilization and mark traffic
Aggregate Policers
PFC QoS applies the bandwidth limits specified in an aggregate policer cumulatively to all flows in
matched traffic. For example, if you configure an aggregate policer to allow 1 Mbps for all TFTP traffic
flows on VLAN 1 and VLAN 3, it limits the TFTP traffic for all flows combined on VLAN 1 and VLAN
3 to 1 Mbps.
•You define per-interface aggregate policers in a policy map class with the police command. If you
attach a per-interface aggregate policer to multiple ingress ports, it polices the matched traffic on
each ingress port separately.
•You create named aggregate policers with the mls qos aggregate-policer command. If you attach a
named aggregate policer to multiple ingress ports, it polices the matched traffic from all the ingress
ports to which it is attached.
•Aggregate policing works independently on each DFC-equipped switching module and
independently on the PFC, which supports any non-DFC-equipped switching modules. Aggregate
policing does not combine flow statistics from different DFC-equipped switching modules. You can
display aggregate policing statistics for each DFC-equipped switching module and for the PFC and
any non-DFC-equipped switching modules supported by the PFC.
•Each PFC or DFC polices independently, which might affect QoS features being applied to traffic
that is distributed across the PFC and any DFCs. Examples of these QoS feature are:
–
Policers applied to a port channel interface.
–
Policers applied to a switched virtual interface.
–
Egress policers applied to either a Layer 3 interface or an SVI. Note that PFC QoS performs
egress policing decisions at the ingress interface, on the PFC or ingress DFC.
Policers affected by this restriction deliver an aggregate rate that is the sum of all the independent
policing rates.