ACE 4710 and DSCP marking

Question

I'm trying to set DSCP flags in traffic from ACE 4710 to clients. Unfortunatly it doesn't seem to work this way:
class-map type http loadbalance match-any URL-AF21
  2 match http url /aaa/.*
  4 match http url /bbb/.*
policy-map type loadbalance http first-match LB-WITH-DSCP
  class URL-AF21
    set ip tos 72
    serverfarm MyServerFram
  class default
    set ip tos 0
    serverfarm MyServerFram
Traffic from ACE to Real Server is tagged but not traffic from ACE to clients.
Any idea which config might work ?

Answer 1

Hi,
If we are setting the TOS Bit in the Policy map, as in you are doing it, ToS Bit will only get set in the ACE to Server Leg of connection. Ace will not set the value for the traffic returning back to Clients.
The way around to this situation is to set the TOS bit via the parameter map and then call it under the class in multimatcg policy. In this way you will have the TOS bit set for both direction of the traffic (From ACE to Server and from ACE to client. The down side of this approach will be that you won't be able to use it for a specific class of traffic.
If you are interested in applying the TOS bit for the whole flows hitting a VIP then please follow this configuration example.
parameter-map type connection SET_TOS
set ip tos 72
Regards,
Kanwal
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