[j-nsp] CoS on Junos5.3

[Sonny]

Hi all,

Recently I started on configuring CoS on Junos5.3R3.4 using the new
syntax.

The goal is to tag the IP-precedence bits (not DSCP) coming in from our
WAN interface to 001, while maintaining other traffic untouched.

On the incoming WAN interface, I have added the following firewall filter:

[firewall filter acl-wan-in]

term permit-any-any {
    then {
        count permit-any-any;
        loss-priority high;
        forwarding-class class-0;
        accept;
    }
}

On other interfaces, The loss-priority bit of incoming packets is
untouched.

Then I configured a rewrite policy on the CoS, following sample config on
the Junos docs:

forwarding-classes {
    queue 0 class-0;
    queue 1 class-1;
    queue 2 class-2;
    queue 3 class-3;
}
interfaces {
    fe-0/2/0 {
        unit 0 {
            rewrite-rules {
                inet-precedence tag-traffic;
            }
        }
    }
}
rewrite-rules {
    inet-precedence tag-traffic {
        forwarding-class class-0 {
            loss-priority low code-point 000;
            loss-priority high code-point 001;
        }
    }
}

Interface fe-0/2/0.0 is the FE interface facing our internal network. Thus
the tagging is done when the packet leaves the router.

The peculiar thing observed is that, the first time when the interface and
rewrite-rules are "commit"-ed at the same time, the TOS bits were not
rewritten. Only when I de-activate the interface under CoS hierarchy (then
commit) and then re-activate the inteface (then commit again) that the TOS
bits were rewritten. I verified the TOS bits by sniffing the fe-0/2/0.0
using tcpdump.

Is this the expected behaviour, or have I missed anything out?

Many thanks for any help rendered.

regards,
sonny