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Shaping
•
Port-based QoS bandwidth shaping. The QoS CLI provides two commands for setting the maxi-
mum ingress and egress bandwidth for a specific port. These QoS port parameters define the rate at
which traffic is received and sent on the specified port. See
on page
21-23.
•
Queue bandwidth shaping. This type of shaping is implemented through the virtual output queue
architecture of the switch. A set of VOQs for each port (QSet) is associated with a profile that defines
and applies the shaping and scheduling configuration for each VOQ in the QSet. See
Management" on page 21-10
Tri-Color Marking
This implementation of a Tri-Color Marking (TCM) provides a mechanism for policing network traffic by
limiting the rate at which traffic is sent or received on a switch interface. The TCM policier meters traffic
based on user-configured packet rates and burst sizes and then marks the metered packets as green,
yellow, or red based on the metering results.
The following diagram illustrates the basic operation of TCM:
The TCM policier meters each packet and passes the metering result along with the packet to the Marker.
Depending upon the result sent by the Meter, the packet is then marked with either the green, yellow, or
red color. The marked packet stream is then transmitted on the egress based on the color-coded priority
assigned.
The TCM Meter operates in Color-Blind mode (the Color-Aware mode is not supported). In the Color-
Blind mode, the Meter assumes that the incoming packet stream is uncolored.
There are two types of TCM marking supported:
•
Single-Rate TCM (srTCM)—Packets are marked based on a Committed Information Rate (CIR) value
and two associated burst size values: Committed Burst Size (CBS) and Peak Burst Size (PBS).
•
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
OmniSwitch AOS Release 7 Network Configuration Guide
for more information.
March 2011
"Configuring Policy Bandwidth Policing"
"Congestion
page 21-21
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