NETGEAR GS752TP, GS728TPP manual Class of Service, Basic CoS Configuration

GS752TP, GS728TP, and GS728TPP Gigabit Smart Switches

Class of Service

The Class of Service (CoS) queueing feature lets you directly configure certain aspects of switch queueing. This configuration 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.

Four queues per port are supported.

From the Class of Service menu under the QoS tab, you can access the following sections:

•Basic CoS Configuration

•CoS Interface Configuration

•Queue Configuration

•802.1p to Queue Mapping

•DSCP to Queue Mapping

Basic CoS Configuration

Use the CoS Configuration screen to set the Class of Service global trust mode. Each port in the switch can be configured to trust one of the packet fields (802.1p or IP DSCP, which is set globally), or to not trust a packet’s priority designation (untrusted mode). If the port is set to a trusted mode, it uses the global trust mode configuration. This mapping table indicates the CoS queue to which the packet must be forwarded on the appropriate egress ports. The trusted field must exist in the packet for the mapping table to be of any use, so default actions are 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 ports, 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.

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