Chapter 11 QoS

 

Table 18

Port Based QoS (continued)

 

LABEL

 

DESCRIPTION

 

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.

 

75

ES-1528 User’s Guide