Configuring QoS Traffic Policing and Shaping
OmniSwitch AOS Release 8 Network Configuration Guide December 2017 page 26-24
Configuring Tri-Color Marking
Tri-Color Marking (TCM) is a supported technique for policing traffic. See “Tri-Color Marking” on
page 26-22 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
greater than the value of the specified CIR. In this case, the trTCM mode is triggered; otherwise, the
srTCM mode is used.
• This implementation of TCM is in addition to the basic rate limiting capabilities provided through the
maximum bandwidth and maximum depth parameters used in QoS policy actions and the ingress and
egress bandwidth parameters used in VLAN Stacking Service Access Point (SAP) profiles. When these
parameters are used, the TCM meter operates in the Single-Rate TCM mode by default.
• A srTCM policy action specifies both a CBS and PBS value. Default values for these burst sizes are
used if one is not specified using the optional cbs and pbs parameters.
• Configure the PBS and CBS with a value that is greater than or equal to the size of the largest IP
packet in the metered stream.
To configure a TCM QoS policy action, use the policy action cir command with one or more of the above
parameters. Configuring the cbs and pbs parameters is optional. If a value is not specified for either one,
the default value is used for both parameters. For example:
-> policy action A1 cir 10M
To specify one or both of the burst size values, use the cbs and pbs parameters. For example:
-> policy action A2 cir 10m cbs 4k
-> policy action A3 cir 10m cbs 4k pbs 10m
All of these command examples configure the TCM meter to operate in the Single-Rate TCM (srTCM)
mode. To configure the meter to operate in the Two-Rate TCM (trTCM) mode, use the pir parameter and
Packet is not CIR/CBS
compliant 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.
TCM Type Meter Compliance Marker Color Result
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