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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
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.
Содержание os6900
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Страница 692: ...Policy Applications Configuring QoS page 25 84 OmniSwitch AOS Release 7 Network Configuration Guide June 2013...