Re: reduce jitter in routed network for voip applications

[Hans Kruse <kruse@xxxxxxxxx>]

That establishment/reservation phase is RSVP; as others have said, 
available in theory, but cannot be assumed to exist in the network in 
general.

On Mar 28, 2005, at 13:26, Daniele Giordano wrote:

> CoS, ToS, QoS work on the information units queued in a buffer of a 
> device.
> I think that, in the same way of a circuit switched network, an
> establishment phase could exist. In this phase the network could 
> reserve the
> right resources.
> i.e. virtual circuit, bandwidth, ....
>
> Thanks.
>
>
> ----- Original Message -----
> From: "Mike S" <ietf@xxxxxxxxxxxxxxx>
> To: "Daniele Giordano" <d.giordano@xxxxxxxxxx>
> Cc: <ietf@xxxxxxxx>
> Sent: Monday, March 28, 2005 1:40 PM
> Subject: Re: reduce jitter in routed network for voip applications
>
>
> > At 06:09 AM 3/28/2005, Daniele Giordano wrote...
> > > RTP is transparent at the transport layer. We analyse TCP and UDP:
> > > TCP is connection oriented and so the communication begins with the
> > > definition of a virtual circuit.
> > > A virtual circuit is a temporary connection of sequence nodes with
> relative
> > > reservation of bandwidth.
> > > A connection oriented service gives the certainty that all 
> > > information
> units
> > > use the same nodes with a same medium latency.
> > > Same latency maintains reduced the jitter.
> >
> > That is incorrect unless _other_, stateful protocols (ex. RSVP, 
> > integrated
> services) are in use throughout the entire network. That is not the 
> general
> case.
> > IP routes on a per hop basis, whether TCP or UDP. There is no "virtual
> circuit" created, except at the endpoints.
> > > I think that RTP should use a layer 4 connection oriented protocol 
> > > (like
> > > TCP) but without retransmissions of information units with excessive
> delay
> > > or errors (like UDP).
> > >
> > > What do you think about this?
> >
> > You're trying to solve a problem which is incorrectly defined, and
> therefore doesn't exist.
> > Diffserv already provides a QoS mechanism for VoIP and does not 
> > require
> gateways to maintain state for each connection. It, like Intserv, 
> cannot be
> assumed to exist through any random Internet path. RFC2474, RFC2475.
> > _______________________________________________
> >
> > Ietf@xxxxxxxx
> > https://www1.ietf.org/mailman/listinfo/ietf
>
>
> _______________________________________________
>
> Ietf@xxxxxxxx
> https://www1.ietf.org/mailman/listinfo/ietf
Hans Kruse, Associate Professor
J. Warren McClure School of Communication Systems Management
Adjunct Associate Professor of Electrical Engineering and Computer 
Science
292 Lindley Hall, Ohio University, Athens, OH, 45701
740-593-4891 voice, 740-593-4889 fax

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