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Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
OL-4266-08
Chapter 42 Configuring PFC QoS
Configuring PFC QoS
When creating a named aggregate policer, note the following information:
• 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.
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Policers applied to a switched virtual interface.
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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.
• In Release 12.2(18)SXE and later releases, you can apply aggregate policers to IPv6 traffic.
• With a PFC3, policing uses the Layer 2 frame size.
• With a PFC2, policing uses the Layer 3 packet size.
• See the “PFC QoS Configuration Guidelines and Restrictions” section on page 42-49 for
information about rate and burst size granularity.
• The valid range of values for the CIR bits_per_second parameter is as follows:
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Minimum—32 kilobits per second, entered as 32000
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Maximum with Release 12.2(18)SXE and later releases:
10 gigabits per second, entered as 10000000000
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Maximum with releases earlier than Release 12.2(18)SXE:
4 gigabits per second, entered as 4000000000
• The normal_burst_bytes parameter sets the CIR token bucket size.
• The maximum_burst_bytes parameter sets the PIR token bucket size.
• When configuring the size of a token bucket, note the following information:
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The minimum token bucket size is 1 kilobyte, entered as 1000 (the maximum_burst_bytes
parameter must be set larger than the normal_burst_bytes parameter).
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The maximum token bucket size is 32 megabytes, entered as 32000000.
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To sustain a specific rate, set the token bucket size to be at least the rate value divided by 4000
because tokens are removed from the bucket every 1/4000th of a second (0.25 ms).
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Because the token bucket must be large enough to hold at least one frame, set the parameter
larger than the maximum size of the traffic being policed.
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For TCP traffic, configure the token bucket size as a multiple of the TCP window size, with a
minimum value at least twice as large as the maximum size of the traffic being policed.