Class Of Service; Cos Configuration - NETGEAR S3300 User Manual

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 Advanced link, the Class of service menu under the QoS tab, you can access the
screens described in the following sections:
•

CoS Configuration

• CoS Interface Configuration
• Interface Queue Configuration
• 802.1p to Queue Mapping
• DSCP to Queue Mapping
CoS Configuration
Use the CoS Configuration screen 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 should 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, so there are default actions performed when this is not the case. 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
port, in accordance with the configured default priority of the ingress port. This process is also
used for cases where a trusted port mapping is unable to be honored, such as when a non-IP
packet arrives at a port configured to trust the IP DSCP value.

To configure CoS trust mode settings on all interfaces:
1. Select QoS > Basic > CoS Configuration.
2. Select the Global radio button to configure the same CoS trust mode settings to all
interfaces
3. From the Global Trust Mode drop down list, select the trust mode for ingress traffic on the
switch.
S3300 Smart Managed Pro Switch
on page 224
on page 226
on page 227
on page 228
on page 228
Configuring Quality of Service
224