Chapter 11 QoS

The following table describes the labels in this screen.

Table 18 Port Based QoS

LABEL

DESCRIPTION

Mode

Select Port Based QoS to specify priority rules based on the port of incoming packets.

 

 

Change

Configure the following:

Priority

• Port - Select the number of the port for which you want to assign IEEE 802.1p priority

 

to incoming frames.

 

• Priority - Select the IEEE 802.1p priority you want to assign to the packets coming

 

into the switch on the port specified in the Port field.

 

Click Change to view your changed settings.

 

Note: The changes are not applied until you click Apply Change

 

Settings.

 

 

Port,

This is a summary table of your port to IEEE 802.1p priority mappings. The Port column

Priority

indicates the port number of the incoming packets and the Priority column indicates

 

what IEEE 802.1p priority gets assigned to those packets.

 

 

Apply

Click this when you have reviewed the changes you want to make and you want to save

Change

them to the switch’s memory.

Settings

 

11.4.2 DSCP Based QoS

The switch allows you to create a mapping table between Differentiated Services Code Points (DSCPs) tags and IEEE 802.1p priority tags.

11.4.3 Differentiated Services Code Point (DSCP) Overview

Differentiated Services (DiffServ) is a class of service (CoS) model that marks packets so that they receive specific per-hop treatment at DiffServ-compliant network devices along the route based on the application types and traffic flow. Packets are marked with DiffServ Code Points (DSCPs) indicating the level of service desired. This allows the intermediary DiffServ- compliant network devices to handle the packets differently depending on the code points without the need to negotiate paths or remember state information for every flow. In addition, applications do not have to request a particular service or give advanced notice of where the traffic is going.

DiffServ defines a new DS (Differentiated Services) field to replace the Type of Service (ToS) field in the IP header. The DS field contains a 2-bit unused field and a 6-bit DSCP field which can define up to 64 service levels.

You can configure the DSCP to IEEE 802.1p mapping to allow the switch to prioritize all traffic based on the incoming DSCP value according to the DiffServ to IEEE 802.1p mapping table.

11.4.4 DSCP Based QoS Screen

You can configure the switch to assign a IEEE 802.1p priority to packets coming into the switch with DSCPs assigned to them. Select DSCP Based QoS in the QoS Enhancement Setting screen to view the following screen.

 

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ES-1552 User’s Guide