Configuring Rewrite Rules Based on PLP

Rewrite rules take action on outgoing packets. When TCM is enabled, M320 and T Series routers support four rewrite PLP designations: low, medium-low, medium-high, and high. To configure the PLP for a rewrite rule, include the following statements at the [edit class-of-service] hierarchy level:

[edit class-of-service]rewrite-rules {(dscp | dscp-ipv6 | exp | ieee-802.1 | inet-precedence) rewrite-name {import (rewrite-name | default);forwarding-class class-name {loss-priority (low | medium-low | medium-high | high) code-point (alias | bits);}}}

The inputs for a rewrite rule are the forwarding class and the loss priority (PLP). The output for a rewrite rule are the CoS values. In other words, a rewrite rule sets the CoS values for each packet exiting the interface with a specific forwarding class and PLP.

For example, if you configure the following, the 000000 CoS values are assigned to all packets exiting the interface with the assured-forwarding forwarding class and medium-high PLP:

class-of-service {rewrite-rules {dscp dscp-rw {forwarding-class assured-forwarding {loss-priority medium-high code-point 000000;}}}}

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