qos dscp mismatch

[mod13]

Hello

If client is sending traffic with dscp 18 tag but server responds with dscp 34..  and if they are all setup correctly to prioritize on lan and wan.  will that create any issue on application?

thanks

[Georg Pauwen]

Hello,

that shouldn't be a problem if both DSCP 18 and DSCP 34 get the same priority. That said, it might be easier to have a policy that rewrites the DSCP value, so only one value is used:

class-map match-all DSCP_REWRITE_CLASS
match dscp af21
!
policy-map DSCP_REWRITE_POLICY
class DSCP_REWRITE_CLASS
set dscp af41

[chrihussey]

So if DSCP 18 and 34 are treated the same from a QoS perspective across the network, there should be no impact. The fact that the DSCP values are different should not have an affect on the application.

Regards

[Joseph W. Doherty]

Depends on if it's truly "and if they are all setup correctly to prioritize on lan and wan."

A Cisco router running "original" WFQ will treat DSCP values, that map to different IPPrec values, differently (and you cannot override that).

If two DSCP values are really treated alike, that may be "now". The reason for having different DSCP values is so you can treat different DSCP markings differently, so what happens may change in the "future". A single application's traffic would generally be expected to have the same DSCP marking regardless of what host sends them.