[mpls-linux-general] Diffserv Over MPLS for Linux.

[ncc49a <nc...@si...>]

Hi James,

    I have thought of a scenario and will like to query u abt it.

Scenario:=20
    An Linux LER is within a Diffserv domain. Thus, it receives non-MPLS =
packets with their DSCP marked.=20

    For packets flowing into the MPLS domain, the LER has to:
a) Convert the DSCP to EXP marked in the shim header via ds2exp
b) For its outgoing interface, it has to convert the EXP mark into a =
tc_index for the traffic scheduler (tc) to police via exp2tc

    For packets flowing out of the MPLS domain, the LER has to:
a)  Convert the EXP of the incoming MPLS packet to DSCP via exp2ds
b)  Use the DSCP to police the outgoing traffic via the traffic =
schedular (tc).

    Am I right to say that:
1) exp2tc is only for outgoing labels and is executed BEFORE the traffic =
scheduler (tc) does its scheduling using the tc_index?
2) ds2exp, exp2ds, set_exp, expfwd will be executed before exp2tc if the =
instructions are executed before i.e

mplsadm -v -A -O gen:41:eth0 -o  ds2exp:0xff:0x1a:0x1
mplsadm -v -O gen:41:eth0 -o  exp2tc:0xff:0x1:0x2
mplsadm -v -O gen:41:eth0 -o  push:gen:41:set:eth0:ipv4:192.168.0.1

The above will map DSCP(0x1a) to EXP(1) and will then convert EXP(1) to =
tc_index(2).

I can then use the traffic scheduler tc to police the traffic based on =
the tc_index 2.

3)    Are the above instructions executed correctly?

    Thanks.

Paul