Yves T'Joens wrote:
>
> Carlos Alberto Kamienski wrote:
> >
> > > >3.2, list, DSCP.
> > > > Why is it only a single DSCP ? Also, is there only a single Flow ID
> > > > per SLS, or can there be many ?
> > >
> > > A set of DSCPs is definitly needed.
> >
> > I think the concept of service should be enforced rather than to imply it
> > by some DSCP(s). What I mean is that, it may not be possible to implement
> > correctly a service just by observing the DSCP, traffic conformance
> > parameters and performance guarantees.
> >
> > For example, it is possible to use a particular PHB (like EF PHB) to
> > deploy different services, but if you want to deploy an end to
> > end service by concatenating some intra-domain services like the Virtual
> > Wire PDB, you must follow this PDB specification. This has an implication
> > even in the network topology.
> >
> > The deployment of such a service may require a previous engineering in
> > the network. Then, the negotiation process (a protocol ?) should be based
> > on services that networks are really able to implement.
> > This leads to something like the QBone BB idea of globally
> > well-known services (GWS). In this case a GWS ID should be included in the
> > SLS along with other parameters that specify paticular levels of this
> > services.
> >
> > Comments ?
> >
>
> Hi Carlos,
>
> you are right in the sense that a service should not particularly map on
> a DSCP. In fact, the choice of DSCP may be signalled back from the
> network to the customer, upon request of a set of certain transport
> characteristics for a certain flow (in the SLS). As an extreme example,
> given enough overdimensioning in a domain, the virtual leased line may
> be offered to best effort traffic...
> As far as globally well-known services concerns, it might help, but i am
> not sure if it is really necessary.
Carlos, Yves,
In the context of the draft, the DSCP is a mean for a flow
specification. If it is signalled by the network, it is specified in the
offer from the network. The DSCP specifed in the SLS draft has in my
understanding nothing to do with the DSCP the packets are market in the
network. But it can be used for the traffic specification.
Marcus
>
> regards,
> Yves
>
> > Regards,
> > Carlos
> >
> > ----------------------------------------------
> > Carlos Alberto Kamienski - cak@cin.ufpe.br
> > Federal University of Pernambuco - Brazil
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