Re: proposed charter 5 priority levels

Curtis Villamizar <[email protected]> wrote on 09/26/2006 12:56:15 PM:

>
> In message
<OFBAA95066.05652C8C-ON852571F5.004A9C8A-852571F5.004B6690@csc.com>
> Janet P Gunn writes:
> >
> >
> > As RFC 4412 makes perfectly clear, the RPH serves a dual role of
signalling
> > priority across an IP network (e.g. from an originating circuit
switched
> > access network to a terminating circuit switched access network) as
well as
> > signalling  priority within the IP network.
> >
> > For each of the namespaces described in RFC 4412, the number of
priority
> > values (5 in most cases, 6 in one) is driven by the former role, based
on
> > the number of priority values in use, or being considered, in the
access
> > network priority scheme.
> >
> > The issue of how many priority levels to differentiate WITHIN the IP
> > network is an issue currently being addressed by vendors and providers.
> >
> > Janet
>
>
> Janet,
>
> You are right, but you may be just focusing on SIP which is one peice
> of the puzzle.
>
> RFC 4412 does not make it perfectly clear whether we need 1 DSCP code
> point, EF, or 5 DSCP code points (IP Prec 0-4?)  or 15 DSCP code
> points (the 4 AF classes plus one more AF class.  Or is it some
> multiple of 6?  This RFC doesn't even mention DSCP.
>
>...
Since 4412 is a SIP document, it would not be appropriate for it to specify
DSCPs.

However, it does say
" While the 'Resource-Priority' header field does not directly
   influence the forwarding behavior of IP routers or the use of
   communications resources such as packet forwarding priority,
   procedures for using this header field to cause such influence may be
   defined in other documents."
which clearly refers to things such as DSCP.