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Catalyst 6500 Series Switch Cisco IOS Software Configuration Guide—Release 12.1 E
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Chapter 31 Configuring PFC QoS
Configuring PFC QoS
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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 Layer 3 packet 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 Layer 3 packet size of the traffic being
policed.
The maximum_burst_bytes parameter is supported with the PFC2. The maximum_burst_bytes
parameter is not supported with the PFC1, but the keyword can be entered with a value equal to the
normal_burst_bytes parameter.
• (Not supported with the flow keyword.) 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—4 gigabits per second, entered as 4000000000
The pir bits_per_second parameter is supported with the PFC2. The pir bits_per_second parameter
is not supported with the PFC1, but can be entered with the PFC1 if the value is equal to the CIR
bits_per_second parameter.
• (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 (see the “Policy Maps” section on
page 31-18 and the “Configuring Policy Map Class Actions” section on page 31-44).
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To set PFC QoS labels in untrusted traffic, you can 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 (with the PFC2, 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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You can enter the drop keyword to drop all matched traffic.
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Ensure that aggregate and microflow policers that are applied to the same traffic each specify
the same conform-action behavior.
• (Optional) For traffic that exceeds the CIR, you can specify an exceed action as follows:
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For marking without policing, you can enter the transmit keyword to transmit all matched
out-of-profile traffic.
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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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You can enter the policed-dscp-transmit keyword to cause all matched out-of-profile traffic to
be marked down as specified in the markdown map (see the “Configuring DSCP Markdown
Values” section on page 31-68).
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.
