Configure Quality of Service
198
ProSAFE 10-Gigabit Smart Managed Switch XS728T and XS748T User Manual
Manage Class of Service
The Class of Service (CoS) queueing feature lets you directly configure certain aspects of
switch queueing. This provides the desired QoS behavior for different types of network traffic
when the complexities of DiffServ are not required. The priority of a packet arriving at an
interface can be used to steer the packet to the appropriate outbound CoS queue through a
mapping table. CoS queue characteristics that affect queue mapping, such as minimum
guaranteed bandwidth or transmission rate shaping, are user configurable at the queue (or
port) level.
Eight queues per port are supported.
From the QoS > CoS > Advanced menu, you can access pages that are described in the
following sections:
• CoS Configuration on page 198
• Configure Global CoS Settings on page 199
• Configure CoS Interface Settings for an Interface on page 199
• Configure the Global CoS Queue Settings on page 201
• Configure the Global 802.1p to Queue Mapping on page 202
• DSCP to Queue Mapping on page 203
CoS Configuration
Use the CoS Configuration page to set the class of service trust mode of an interface. Each
port in the switch can be configured to trust one of the packet fields (802.1p or IP DSCP), or
to not trust any packet’s priority designation (untrusted mode). If the port is set to a trusted
mode, it uses a mapping table appropriate for the trusted field being used. This mapping
table indicates the CoS queue to which the packet must be forwarded on the appropriate
egress port. Of course, the trusted field must exist in the packet for the mapping table to be of
any use. If this is not the case, default actions are performed. These actions involve directing
the packet to a specific CoS level configured for the ingress port as a whole, based on the
existing port default priority as mapped to a traffic class by the current 802.1p mapping table.
Alternatively, when a port is configured as untrusted, it does not trust any incoming packet
priority designation and uses the port default priority value instead. All packets arriving at the
ingress of an untrusted port are directed to a specific CoS queue on the appropriate egress
ports, in accordance with the configured default priority of the ingress port. This process is
also used for cases where a trusted port mapping cannot be honored, such as when a non-IP
packet arrives at a port configured to trust the IP DSCP value.
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