Using Multifield Classifiers to Set PLP

Multifield classifiers take action on incoming or outgoing packets, depending whether the firewall rule is applied as an input filter or an output filter. When TCM is enabled, Juniper Networks M320 Multiservice Edge Routers and T Series Core Routers support four multifield classifier PLP designations: low, medium-low, medium-high, and high.

To configure the PLP for a multifield classifier, include the loss-priority statement in a policer or firewall filter that you configure at the at the [edit firewall] hierarchy level:

The inputs (match conditions) for a multifield classifier are one or more of the six packet header fields: destination address, source address, IP protocol, source port, destination port, and DSCP. The outputs for a multifield classifier are the forwarding class and the loss priority (PLP). In other words, a multifield classifier sets the forwarding class and the PLP for each packet entering or exiting the interface with a specific destination address, source address, IP protocol, source port, destination port, or DSCP.

For example, in the following configuration, the forwarding class expedited-forwarding and PLP medium-high are assigned to all IPv4 packets with the 10.1.1.0/24 or 10.1.2.0/24 source address:

To use this classifier, you must configure the settings for the expedited-forwarding forwarding class at the [edit class-of-service forwarding-classes queue queue-number expedited-forwarding] hierarchy level. For more information, see Overview of Forwarding Classes.