Rewrite rules take action on outgoing packets. When TCM is enabled, T-series and M320 platforms 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 Configuring Forwarding Classes.