OmniSwitch os6900 User Manual

Traffic Policing and Shaping Configuring QoS
page 25-24 OmniSwitch AOS Release 7 Network Configuration Guide June 2013
• Two-Rate TCM (trTCM)—Packets are marked based on a CIR value and a Peak Information Rate
(PIR) value and two associated burst size values: CBS and PBS.
Both srTCM and trTCM operate in the same basic manner, as shown in the above diagram. The main
difference between the two types is that srTCM uses one rate limiting value (CIR) and trTCM uses two
rate limiting values (CIR and PIR) to determine packet marking.
The type of TCM used is determined when the policier is configured; depending on which rates and burst
size values are configured, TCM functions in ether single-rate or two-rate mode. There is no explicit
command to select the type of TCM. See “Configuring Tri-Color Marking” on page 25-24 for more infor-
mation.
Based on the TCM type used, packets are marked as follows:
Configuring Tri-Color Marking
Tri-Color Marking (TCM) is a supported technique for policing traffic. See “Tri-Color Marking” on
page 25-23 for an overview of how this implementation of TCM works.
Configuring TCM is done by creating a TCM policy action using the following QoS policy action
command parameters:
> cir (Committed Information Rate, in bits per second)
> cbs (Committed Burst Size, in bytes)
> pir (Peak Information Rate, in bits per second)
> pbs (Peak Burst Size, in bytes)
> color-only (mark packet color only)
Consider the following when configuring TCM policy actions:
• There is no explicit CLI command to specify the mode in which the TCM meter operates. This mode is
determined by whether or not the PIR is configured for the policy action and if the value of the PIR is
TCM Type Meter Compliance Marker Color Result
Single-Rate
(srTCM)
Packet is CIR/CBS compliant. GREEN Packet is transmitted with the Drop
Precedence set to LOW.
Packet is not CIR/CBS compli-
ant but is CIR/PBS compliant.
YELLOW Packet is transmitted with the Drop
Precedence set to HIGH (packet is
dropped first when congestion
occurs on the egress queue.
Packet is neither CIR/CBS nor
CIR/PBS compliant.
RED Packet is dropped at the ingress.
Two-Rate
(trTCM)
Packet is CIR/CBS compliant. GREEN Packet is transmitted with the Drop
Precedence set to LOW.
Packet is not CIR/CBS compli-
ant but is PIR/PBS compliant.
YELLOW Packet is transmitted with the Drop
Precedence set to HIGH (packet is
dropped first when congestion
occurs on the egress queue.
Packet is neither CIR/CBS nor
PIR/PBS compliant.
RED Packet is dropped at the ingress.

OmniSwitch os6900 Specifications

General

Brand	OmniSwitch
Model	os6900
Category	Switch
Language	English