QoS for voice traffic

Differentiated Services Code Point A way to classify packets in QoS.

CS5 is the same as IP precedence 5.

Normally I think call setup traffic is marked as AF31 and rtp traffic marked with precedence 5.

So your access list matches both controlsignaling and voice traffic.

Some but not all makers of VoIP systems mark their traffic, to see if this is the case with the Alcatel you could just apply this access list to the port the pbx is connected to and see if the counters go up.

Or you could classify the packets yourself.

-SAto

Thanks a lot Sato, you gave me the right hints! So this is part of an QoS config, where voice traffic is prioritised "after" the DiffServ - method?

Cheers, Mike

snipped-for-privacy@hotmail.com skrev:

Yes, but depending on where this access list is actually used it can be used to reclassify or prioritize.

-SAto

"depending on where this access list is actually used " Or not at all.

VOICE is just an arbitrary label and for QoS the access-list can be applied to a 'policy map' and then that in turn applied using a 'service-policy' statement to an interface.

'voice traffic is prioritised "after" the DiffServ - method'

Are you thinking of "after" as in later than?

It is not later than.

I would say:- 'voice traffic is prioritised using the DiffServ - method'

The other BIG one to look out for is that by default some network equipment resets the diffserv bits to zero as the traffic passes through it.

Hi,

You're right, my English unfortenetely is not the best :)

Generally speaking, what equipment does that (a special brand)? That means, if I want to match the mentioned dscp's, I (or the pbx) first has to mark it?

Thanks a lot

I am not absolutely sure about this since my experience is limited however I suspect that unless specifically configured to do so Cisco switches will

I am not absolutely sure about this since my experience is limited however I believe that Cisco switches will clear any diffserv (or TOS) bits. To avoid that they have to be specifically configured.