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Cisco IOS XE Integrated Session Border Controller Configuration Guide for the Cisco ASR 1000 Series Aggregation Services Routers
OL-15421-01
Chapter 5 Quality of Service and Bandwidth Management
Two-Rate Three-Color Policing and Marking
• Traffic not conforming to the lower sdr rate, but conforming to the higher pdr rate.
These packets are colored with the marker DSCP value and pdr configured with the control-dscp
value1 marker-dscp value2 pdr-coefficient value3 command.
–
The control-dscp value1 keyword enables the Two-Rate Three-Color Policing and Marking
feature for a specific flow if value1 matches the DSCP value for the flow in the diffserv package
transmitted via H.248.
–
The marker-dscp value2 keyword colors traffic packets with a DSCP value2. This traffic
conforms to the peak data rate (pdr), but does not conform to the sustainable data rate (sdr).
–
The pdr-coefficient value3 keyword applies the following formula to calculate the pdr value
(which is not passed from H.248).
The pdr-coefficient value is calculated as pdr = sdr * value3 /100 (and pdr must be greater than
sdr).
• Traffic not conforming to either of the sdr or pdr rates.
These packets are dropped.
Note The Two-Rate Three-Color Policing and Marking feature is not enabled for a particular flow if
the DSCP value set by H.248 for that flow does not match the configured control-dscp value1.
Traffic flows must have the Two-Rate Three-Color Policing and Marking feature enabled to use the three
parameters configurable with the Two-Rate Three-Color CLI. Traffic flows that do not have the
Two-Rate Three-Color Policing and Marking feature enabled are subject to normal Tman-based policing
with pdr, sdr, and mbs parameters configured via H.248, regardless of the pdr coefficient configured via
the Two-Rate Three-Color CLI.
The DBE supports dual token bucket policing to support this feature. The DBE uses a “token bucket
algorithm” to manage the maximum rate of traffic. This algorithm is used to define the maximum rate
of traffic allowed on an interface at a given moment in time. The token bucket algorithm processes as
follows—each arriving packet’s size (frame’s size) is subtracted from the contents of the bucket. If the
bucket does not have enough tokens for the arriving packet, the packet is dropped and no tokens are
removed. The passage of time fills the bucket with tokens and the dispatching of a packet depletes the
bucket.
DBE Restrictions
The following are DBE restrictions for the Two-Rate Three-Color Policing and Marking feature:
• The DSCP values configured via CLI are global. Specifically, the DSCP values are shared among
all the terminations when this feature is enabled.
• The Two-Rate Three-Color CLI is only applicable to future new call flows and do not trigger any
backtrack to established terminations.
• A media gateway controller (MGC), also called the SBE, is only able to use the Tman fields if the
DBE supports the various features which make up Tman support.