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Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
OL-4266-08
Chapter 41 Configuring PFC QoS
Configuring PFC QoS
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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 512 megabytes, entered as 512000000.
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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.
• The valid range of values for the pir bits_per_second parameter is as follows:
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Minimum—32 kilobits per second, entered as 32000 (the value cannot be smaller than the
CIR bits_per_second parameters)
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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
• (Optional) You can specify a conform action for matched in-profile traffic as follows:
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The default conform action is transmit, which sets the policy map class trust state to trust
DSCP unless the policy map class contains a trust command.
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To set PFC QoS labels in untrusted traffic, enter the set-dscp-transmit keyword to mark
matched untrusted traffic with a new DSCP value or enter the set-prec-transmit keyword to
mark matched untrusted traffic with a new IP precedence value. The set-dscp-transmit and
set-prec-transmit keywords are only supported for IP traffic. PFC QoS sets egress ToS and
CoS from the configured value.
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Enter the drop keyword to drop all matched traffic.
Note When you configure drop as the conform action, PFC QoS configures drop as the exceed
action and the violate action.
• (Optional) For traffic that exceeds the CIR, you can specify an exceed action as follows:
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The default exceed action is drop, except with a maximum_burst_bytes parameter (drop is not
supported with a maximum_burst_bytes parameter).
Note When the exceed action is drop, PFC QoS ignores any configured violate action.
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Enter the policed-dscp-transmit keyword to cause all matched out-of-profile traffic to be
marked down as specified in the markdown map.
Note When you create a policer that does not use the pir keyword and the maximum_burst_bytes
parameter is equal to the normal_burst_bytes parameter (which is the case if you do not enter
the maximum_burst_bytes parameter), the exceed-action policed-dscp-transmit keywords
cause PFC QoS to mark traffic down as defined by the policed-dscp max-burst markdown
map.
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