Rewriting Frame Relay Headers
Assigning the Default Frame Relay Rewrite Rule to an Interface
For Juniper Networks device interfaces with Frame Relay encapsulation,
you can rewrite the discard eligibility (DE) bit based on the loss
priority of Frame Relay traffic. For each outgoing frame with the
loss priority set to low, medium-low, medium-high, or high, you can
set the DE bit CoS value to 0 or 1. You can
combine a Frame Relay rewrite rule with other rewrite rules on the
same interface. For example, you can rewrite both the DE bit and MPLS
EXP bit.
The default Frame Relay rewrite rule contains the following settings:
loss-priority low code-point 0; loss-priority medium-low code-point 0; loss-priority medium-high code-point 1; loss-priority high code-point 1;
This default rule sets the DE CoS value to 0 for each outgoing frame with the loss priority set to low
or medium-low. This default rule sets the DE CoS value to 1 for each outgoing frame with the loss priority set to medium-high
or high.
To assign the default rule to an interface, include
the frame-relay-de default statement at the [edit class-of-service
interfaces interface interface-name unit logical-unit-number unit rewrite-rules] hierarchy
level:
[edit class-of-service interfaces interface-name unit logical-unit-number rewrite-rules] frame-relay-de default;
Defining a Custom Frame Relay Rewrite Rule
To define a custom Frame Relay rewrite rule, include
the following statements at the [edit class-of-service] hierarchy level:
[edit class-of-service]
rewrite-rules {
frame-relay-de rewrite-name {
import (rewrite-name | default);
forwarding-class class-name {
loss-priority level code-point (0 | 1);
}
}
}
A custom rewrite rule sets the DE bit to the 0 or 1 CoS value based on the assigned loss priority
of low, medium-low, medium-high, or high for each outgoing frame.
The rule does not take effect until you apply it
to a logical interface. To apply the rule to a logical interface,
include the frame-relay-de map-name statement at the [edit class-of-service interfaces interface interface-name unit logical-unit-number rewrite-rules] hierarchy level:
[edit class-of-service interfaces interface-name unit logical-unit-number rewrite-rules] frame-relay-de map-name;