Carlos Alberto Kamienski wrote:
>
> Hello Martin
>
> I know the the AQUILA notion of predefined services. However, some time
> ago in this list I introduced the idea of a homogenous view of services
> (well-known services) in order to guarantee that the end to end service
> semantic will be preserved, but someone told me that a predefined service
> is just a compression of an SLS, to make easier the negotiation. That is,
> it seemed to me that we had different views.
And I still have the opinion. I am fine with well-known services, but
they need to be clearly specified with a SLS and all the parameters
(wether the parametes are fixed, pre-defined or negotiatable is another
issue.
>
> Now, people are discussing ways of service specification through SLSs
> between domains, and I still think that domains should negotiate end to
> end services, not just edge-to-edge behaviour or PDB. If one has a service
> definition which is suported by a group of domains, each domains could in
> principle use any QoS technology it wants, as long as it preserves the
> service characteristics.
I think there is a difference in the negotiation model between different
parties. Some people think a value-added service provider (sorry for the
term from telecommunications :-) is negoating with many domains in order
to setup an end-to-end service, which is sold to customers. In the
second model, a customer directly negotiates with his peer ISP (possible
more then one) about end-to-end services.
Marcus
>
> Regards
>
> Carlos
>
> > Hello Carlos,
> >
> > that "notion of an end to end service, that is supposed to provide the guarantees for users applications" is exactly what AQUILA calls a (predefined) Network Service. We support the idea, that the user -- beside the technical parameters of the reservation like traffic characteristics -- will specify a network service. The provider associates some guarantees or weeker, just some characteristics with this network service and offers this to the customer.
> >
> > We think, that the definition of such network services is a prerequisite for successful negotiation of services between the customer and the provider.
> >
> > Best regards
> >
> > --
> > Martin Winter
> >
> > ------------------------------------------------------
> > Siemens AG Voice: +49 89 722-63718
> > ICN WN CC EK A19 Fax: +49 89 722-41920
> > Hofmannstr. 51 Mail: Martin.Winter@icn.siemens.de
> > 81359 Muenchen
> > Germany
> >
> > > -----Original Message-----
> > > From: Carlos Alberto Kamienski [SMTP:cak@cin.ufpe.br]
> > > Sent: Friday, February 09, 2001 9:52 AM
> > > To: sls@ist-tequila.org
> > > Cc: diffserv-interest@external.cisco.com
> > > Subject: Re: [tequila/sls] Re: [Diffserv-interest] A question on the relationshipbetweenSLA and service class
> > >
> > > > I think the question of just what is being exposed and what is being
> > > > kept private does turn on how the SLS is expected to be used. If
> > > > it is something that is communicated between a customer and a provider,
> > > > then it seems quite reasonable that a provider should NOT necessarily
> > > > exposed PHBs used nor even certain quality measures that are not
> > > > those that the customer is being "guaranteed". Brian and I have said
> > > > repeatedly that what PDB a provider is using is not really expected
> > > > to be exposed; a PDB is an additional part of the diffserv toolkit that
> > >
> > > Ok, if neither the PDB nor the PHB are expected to be exposed, than in my
> > > opinion a piece is missing in this puzzle. Users don't care about PHB,
> > > PDB, or intserv services or anything else. And , the
> > > edge-to-edge behaviour is not enough to guarantee the end to end behaviour
> > > users are really concerned about.
> > > What is missing, IMHO, is the the notion of an end to end service, that
> > > is supposed to provide the guarantees for users applications.
> > > I personally like the idea of well-known-services (wks) of Internet2
> > > Qbone (they call it a global wks, but I think it does not need to be
> > > necessarily global, just end to end).
> > > Then, what providers will expose will be this wks, instead of PHBs, PDBs,
> > > DSCPs, etc. Because, since PHBs and PDBs refers to internal stuff and
> > > aren't supposed to be seen by external uses, then users don't see diffserv
> > > at all (DSCP may be changed at the border).
> > >
> > > I think, an e2e service needs a known e2e definition (and maybe a code)
> > > in order to provide an even e2e guarantee along the entire paths between
> > > source and destination. And the negotiation process will become easier as
> > > well.
> > >
> > > Carlos Kamienski
> > >
> > >
> > > > it supposed to give a recipe for putting pieces together in a
> > > >certain
> > > > way and ending up with a certain treatment (generally quantified by
> > > > metrics) that a packet of the traffic aggregate using that PDB can
> > > > expect. One can envision various ways of using this. The two that
> > > > occur to me immediately is: 1) I want to offer a certain "service level"
> > > > to a customer class. I browse existing PDBs to see how to find one
> > > > that can let me select the parameter of interest. Maybe I get some
> > > > other attributes, too, but I don't want to sell those features, so
> > > > I don't talk about them. Or 2) I decide I want to offer a particular
> > > > sort of treatment that some PDB can be configured to provide (VW may
> > > > be an example of this). I read the PDB document to figure out how to
> > > > set up my network for this and what behavior I should expect. I sell
> > > > something that is spec'd lower than the "expected" behavior to be>
> > > > on the safe side. In either case, I don't necessarily want to say
> > > > what PDB I'm using, at least in part because I don't want customers
> > > > demanding the other measureable properties of that PDB in case I
> > > > want to use a different PDB that offers the same measure that I sold
> > > > them, but not the others. Also, it may be a proprietary PDB.
> > > >
> > > > I think Brian's point about exposing PHBs has more to do with *if*
> > > > premarking is part of your agreement. I believe he used the word "may".
> > > >
> > > > I'm not all that certain myself how people expect to use an SLS.
> > > > If it doesn't "hide" the implementation details for the particular
> > > > "service" from a customer then it seems like it may not differ
> > > > from the RFC2475 term Service Provisioning Policy. I also think, on
> > > > rereading rfc2475, that "service" in that document is generally used as
> > > > we are using PDB "the service provided to a traffic aggregate" though
> > > > the PDB notion is specific to a single domain.
> > > >
> > > > Kathie
> > > >
> >
--Dr. Marcus Brunner C&C Research Laboratories NEC Europe Ltd.
E-Mail: brunner@ccrle.nec.de WWW: http://www.ccrle.nec.de/ personal home page: http://www.tik.ee.ethz.ch/~brunner
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This archive was generated by hypermail 2b29 : Fri Feb 09 2001 - 14:03:53 CET