MLS QOS: 3560 vs 3550

Hello,

I am testing policing. Here is diagram:

R1--\
     3560(f0/19)----trunk----(f0/19)3550(f0/3)-----R3
R2--/

I am policing traffic from R1,R2 to R3
R1 sends packets marked DSCP 10
R2 sends packets marked DSCP 20
Policy map is applied on 3550 int f0/19:

Policing seems to work because I can see ping drops on R1 or R2 as soon as
service policy is applied on 3550, int f0/19.
My problem is that 3550 rewrites all dscps to 0 as soon as mls qos is
enabled. On 3560 I can disable dscp rewrites with command "no mls qos
rewrite ip dscp" but on 3550 there is no such command.

Is there a way not to rewrite DSCPs on 3550 so R3 will receive packets as
marked by R1 and R2?

I know that there is no 3550 on the lab anymore but just want to understand
how
this works...

Thanks,

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Received on Thu Jan 21 2010 - 11:05:03 ART