Junos OS

Hi everybody,

Please consider the following example on “REWRITE RULE” on MX5.

g0/1/0.0—MX5---g0/2/0.0

On g0/1/0.0, we have a classifier JEE which places all traffic with DSCP code points: 010101, 010111 into egress forwarding class CRITICAL on g0/2/0.0:

class-of-service {

   classifiers {

       dscp JEE

                     forwarding-class CRITICAL {

               loss-priority high code-points 010111;

               loss-priority low code-points 010101;

On egress port 0/2/0.0, we have a re write rule JOO that remarks DSCP value on all traffic in egress forwarding class CRITICAL on g0/2/0.0

rewrite-rules {

       dscp JOO

               forwarding-class CRITICAL {

               loss-priority low code-point 010101;

               loss-priority high code-point 010111;

Let say a packet with DSCP 010111 arrives on g0/1/0.0, our router classifies it  based on classifier JEE,  and places it into FORWARDING CLASS CRITICAL on egress interface g0/2/0.0

Since g0/2/0.0 has a REWRITE RULE JOO, router has to remark the DSCP value with either 010101 or 010111, question is which value will be used for remarking DSCP 010111 or 010111?

Much appreciated!!

Hi,

From the JEE BA classifier, dscp 010111 is assigned to FC CRITICAL with packet loss-priority [plp] high.

JOO re-write rule will dscp re-mark packets in FC CRITICAL as below:

plp=high, dscp re-write: 010111

plp=low, dscp re-write: 010101

Hope this helps.

Cheers,

Ashvin