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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
–
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).
–
The maximum token bucket size is 512 megabytes, entered as 512000000.
–
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).
–
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.
–
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:
–
Minimum—32 kilobits per second, entered as 32000 (the value cannot be smaller than the
CIR
bits_per_second
parameters)
–
Maximum with Release 12.2(18)SXE and later releases:
10 gigabits per second, entered as 10000000000
–
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:
–
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.
–
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.
–
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:
–
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.
–
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.
