6-7
Cisco 10000 Series Router Quality of Service Configuration Guide
OL-7433-09
Chapter 6 Policing Traffic
Single-Rate Color Marker for Traffic Policing
police Command History
Usage Guidelines for the police Command
A packet is classified as conforming (or of color green) if its size is at most the size of the normal or
committed burst (bc) and within the allowance of the committed information rate (CIR).
A packet is classified as exceeding (or of color yellow) only if its size is greater than the allowance of
the CIR, but is at most the number of bytes of the excess burst (be) and within the available surplus.
A packet is classified as violating (or of color red) only if its size is greater than both the CIR allowance
and the available surplus, either because the packet’s size exceeds the excess burst (be) size or because
a previous packet used some of the surplus and the traffic since then has not slowed sufficiently to
acquire the surplus needed for the current packet. The policer starts with a surplus equal to the excess
burst (be) size and replenishes it by the amount of unused CIR allowance until the surplus reaches the
be size.
The policer measures the committed burst size (CBS) and the excess burst size (EBS) in bytes. The
Cisco IOS software converts the policing rate you enter in bits per second to bytes per millisecond. You
must configure the CBS and EBS so that at least one of them is larger than 0.
When the
be
value equals 0, we recommend that you set the egress
bc
value to be greater than or equal
to the ingress
bc
value plus 1. Otherwise, packet loss can occur. For example:
be = 0
egress bc >= ingress bc + 1
Cisco IOS Release
Description
Release 12.0(17)SL
The
police
command was introduced on the PRE1 and included a
single-rate two-color marker.
Release 12.0(22)S
This command was enhanced to include the
set-mpls-exp-transmit
policing action.
Release 12.0(25)S
This command was enhanced to include a three-color marker. A new
violate-action
parameter allows you to specify the action to take for traffic
that consistently violates the committed rate.
Release 12.2(16)BX
This command was introduced on the PRE2 and included a single-rate
two-color marker.
Release 12.3(7)XI
This command was enhanced on the PRE2 and included a three-color
marker and the
set-mpls-exp-imposition-transmit
policing action. This
action is available on the PRE2 only.
Release 12.2(28)SB
This command was integrated in Cisco IOS Release 12.2(28)SB for the
PRE2.
Release 12.2(31)SB2
This command was introduced on the PRE3 to allow you to police traffic on
the L2TP access concentrator (LAC) based on the value of a packet’s IP
DSCP bits. The
set-frde-transmit
policing action was also added for the
PRE3.
