Users Guide

1486 Differentiated Services
• Packets that are pre-colored yellow and exceed the PIR will be colored red.
This does not apply to the simple algorithm since there is no yellow pre-
coloring.
• Packets that are pre-colored red remain colored red.
Refer to RFC 2697 and RFC 2698 for further detail on color-aware and color-
blind processing.
Simple Meter Implementation
The simple algorithm meters a traffic stream and colors packets red or green
according to two parameters, the Committed Information Rate (CIR) and
the Committed Burst Size (CBS). If the CIR is violated, the offending
packets are colored red, otherwise, they are colored green.
In color-aware mode, packets may also be pre-colored red based on user-
defined criteria. Packets that are pre-colored red are considered for discard as
if the simple rate meter had colored them red as a result of exceeding the
meter. Pre-colored packets may not be re-colored to green by the meter.
It is recommended that the CBS parameter be set to the largest IP packet size
that can be legally transported.
Single Rate Meter Implementation
The police-one-rate algorithm implements a single-rate Three Color Marker
(srTCM) per RFC 2697. The srTCM algorithm is useful in situations where
the length of the burst is the distinguishing factor for determining service
eligibility and the peak rate is not considered. A srTCM meters a traffic
stream per the Committed Burst Size (CBS) and Excess Burst Size (EBS)
parameters and colors packets according to the Committed Information Rate
(CIR), the CBS and the EBS. At least one of the CBS or EBS must be greater
than 0. It is recommended that when the CBS or EBS parameters are larger
than 0, they be configured to be greater than or equal to the largest IP packet
size that can be legally transported. In color-blind mode, a packet is colored
green if it does not exceed the CBS, yellows if it exceeds the CBS but not the
EBS, and red if it exceeds both.
In color-aware mode, packets may be pre-colored yellow or red based on user-
defined criteria prior to being processed by the meter. Packets that are pre-
colored yellow or red are considered for discard as if the meter had colored