Quanta Cloud Technology QuantaMesh QNOS5, Configuration Manual

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Defining these settings on a per-queue basis allows the user to create the desired service characteristics for
different types of traffic. The tail drop and WRED parameters are specified individually for each supported
drop precedence level.
In addition, the following settings can be specified on a per-interface basis:

Queue management type: tail drop vs. WRED (only if per-queue configuration is not upported)

WRED decay exponent
9.4.1.4. Traffic Class Groups
In QNOS platforms that support multiple levels of egress scheduling, the Traffic Class Groups (TCGs) extend
the egress queuing to make use of multiple levels of scheduling. A TCG defines a collection of egress COS
Queues. The configuration parameters for the TCG specify the class of service characteristics applied to the
aggregated traffic from the associated COS queues. This involves setting the following configuration
parameters to each TCG.

Map one or more COS queues to the TCG.

Set the scheduling type for each TCG: Strict vs. WDRR

Set the weight percentages for each TCG.

Set the minimum guaranteed bandwidth for each TCG. The minimum bandwidth is specified
in terms of the percentage of the total link bandwidth.

Set the maximum allowed bandwidth for each TCG. The maximum bandwidth is specified in
terms of the percentage of the total link bandwidth.
TCG configuration parameters are similar to that of COS queues. That is, the configuration of scheduling
attributes such as minimum bandwidth, maximum bandwidth, and scheduling algorithm also apply to TCG.
The behavior of a TCG with respect to scheduling algorithm and bandwidth allocation configuration is the
same as that of COS Queues.
Each TCG is associated with a weight percentage which defines the priority of the TCG to be serviced when
WDRR is configured as the scheduling type of the TCG. The weight of the TCG is used only after the minimum
guaranteed bandwidth of each of the TCG is met and after all the strict priority TCGs are serviced. The
weight of the TCG is then used to prioritize the TCGs among the TCGs that are configured for WDRR.
9.4.2. Configuring CoS Queuing and ETS
This example shows the manual configuration of the CoS queuing feature in a network where traffic needs
to be prioritized based on the protocol frame-loss tolerance. For example, FCoE traffic is highly sensitive to
traffic loss. If a port has both loss-sensitive data and other less loss-sensitive data, then the loss-sensitive
data is categorized into the same TCG to provide control over the bandwidth allocation and scheduling for
the loss- sensitive traffic.
In this example, loss-sensitive traffic is sent with an 801.p priority value of 4, and less loss-sensitive traffic is
sent with an 801.p priority value priority of 1. The following steps show how to configure the switch to
prioritize the traffic.