[c-nsp] QoS question

[Djerk Geurts]

Without nbar one generally classifies RTP and RTCP by specifying the range
from 16384 up to 32768. Even ports are RTP and RTCP uses the uneven ports in
the same range.

>From an IETF doc:
"For UDP and similar protocols, RTP SHOULD use an even
destination port number and the corresponding RTCP stream
SHOULD use the next higher (odd) destination port number."

Nbar allows one to select RTP on whatever port it might be using, I recal
Cisco checking the L4 header.

> >> class-map match-any video-voice
> >> match protocol rtp audio
> >> match protocol rtp video
You might want to consider removing the audio statement. Definetely classify
at ingress and mark the traffic if you're allowed to do so. Another option
is to have the applications using RTP mark the packets using ip prec or dscp
and classify on that. To give you even more options many voip
implementations split the voip traffic from the data traffic on the LAN by
utilising separate vlans and thus separate ip segments enabling qos
classification by ip address. Though one has to realise that this wouldn't
cover softphones.

-- 
Djerk
www.djerk.nl 

> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net 
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of 
> Collins, Richard (SNL US)
> Sent: woensdag 21 februari 2007 19:36
> To: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] QoS question
> 
> Hi,
> 
> I would be just curious on a few further details.
> I have seen the option to use under class-map
> match ip rtp 16384 16383
> 
> I interpret this to mean to match the even port numbers used 
> by rtp but
> you are missing control messages (rtcp) - therefore only matching
> payload.
> Is there some other reason to prefer the match command (match protocol
> rtp audio)?
> If you don't have nbar how do you match the rtcp - udp port range?
> 
> Thanks
> Richard
> 
> >Date: Tue, 20 Feb 2007 20:50:08 -0600
> >From: "Nick Griffin" <nick.jon.griffin at gmail.com>
> >Subject: Re: [c-nsp] QoS question
> >To: "Joseph Jackson" <JJackson at aninetworks.com>
> >Cc: Cisco-NSP Mailing List <cisco-nsp at puck.nether.net>
> >Message-ID:
> >       <a2b352c40702201850q33559c9bi930f8c0c5bbd5f66 at mail.gmail.com>
> >Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> >
> >Joseph, when congestion is not occuring, bandwidth allocated to the
> priority
> >queue will be available for use by other traffic. Be sure your nbar
> matching
> >actually does match the particular audio and video you wish to match.
> I'm
> >not sure about the Video port numbers used by nbar right off 
> hand, but
> the
> >RTP is 16384 to 32767. You might also want to match the 
> traffic on the
> >ingress with a different class map and use a new policy to set your
> dscp
> >values, as opposed to doing it on the egress. I've ran into issues in
> the
> >past with order of operations.
> >
> >HTH
> >
> >Nick Griffin
> >
> >
> >On 2/20/07, Joseph Jackson <JJackson at aninetworks.com> wrote:
> >>
> >> Hey guys,
> >>
> >>         I'm working on getting QoS setup on my WAN links for voice
> and
> >> video.  Here's the config example I've worked up.
> >>
> >>
> >> class-map match-any video-voice
> >> match protocol rtp audio
> >> match protocol rtp video
> >>
> >>
> > 
> 
> 
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