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-dscpvalue1 marker-dscpvalue2 pdr-coefficientvalue3 command.
–The control-dscpvalue1 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-dscpvalue2 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-coefficientvalue3 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-dscpvalue1.
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.
Cisco IOS XE Integrated Session Border Controller Configuration Guide for the Cisco ASR 1000 Series Aggregation Services Routers
