RE: WG last call: draft-ietf-tewg-diff-te-reqts-04.txt

[Jim Boyle <jboyle@pdnets.com>]

Well, it's seems long-winded, but I suppose I can go along with that.

Let's remove the reference, and add:

(5) maximizes efficient use of the network.

Is the WG ok with that?  Waisum - would that be a workable compromise?

Jim

On Wed, 5 Jun 2002, Lai, Wai S (Waisum), ALASO wrote:

> Jim,
>    Per your request, here is the proposed text to replace the last
> but one paragraph of Section 3.3.  Comments are welcome.
> Thanks, Wai Sum.
>
> At the time of writing this document, it is not clear whether a
> single model of Bandwidth Constraints is sufficient, which one it
> should be and how flexible this model really needs to be and what
> are the implications on the DS-TE technical solution and its
> implementations.  Work is currently in progress [Reference] to
> investigate the performance and trade-offs of the different
> operational aspects of Bandwidth Constraints.  For example,
> preliminary results indicate that the use of a higher degree of
> bandwidth sharing among different services can lead to a tighter
> coupling among them, which can result in the impact of one service
> on another.  Another preliminary observation is that there is the
> need to balance overall efficiency and the avoidance of starvation
> of any one service.  These factors should be considered in the
> deployment of any bandwidth constraint model.
>
> The DS-TE technical solution must specify one
> default bandwidth constraint model which must be supported by any
> DS-TE implementation.  Having a default bandwidth constraint model
> allows for the network administrator to have at least one
> consistent behavior when working with multiple implementations of
> DS-TE.  Additional bandwidth constraint models may also be specified.
> In the selection of a default model, at least the following criteria
> must be considered:
> (1) addresses the scenarios in Section 2
> (2) works well under both normal and overload conditions
> (3) applies equally when preemption is either enabled or disabled
> (4) minimizes signaling load processing requirements
>
> [Reference] W.S. Lai, "Performance evaluation of bandwidth allocation
>   models for Diffserv-aware MPLS traffic engineering," Internet-Draft,
>   June 2002.
>
> -----Original Message-----
> From: Jim Boyle [mailto:jboyle@pdnets.com]
> Sent: Tuesday, June 04, 2002 3:00 PM
> To: Lai, Wai S (Waisum), ALASO
> Cc: Ash, Gerald R (Jerry), ALASO; te-wg@ops.ietf.org
> Subject: RE: WG last call: draft-ietf-tewg-diff-te-reqts-04.txt
>
>
>
> You're text does not make it "clear" to me.
>
> Can you propose some text which captures what you see as objective
> criteria?
>
> My pass would be to add a sentence at the end of the paragraph such as:
>
> "The default bandwidth model should be one that can address the
> scenarios
> in section 2 in a manner which balances bandwidth efficiency as well as
> signaling overhead."
>
> I'm not sure if that will allow us to converge on a model, but at least
> it
> specifies some objective criteria to judge different models by.  Plus,
> with just one sentence and no value statements on models as you had
> previously suggested, I think we can add it in and progress the draft.
>
> Does this sound ok?
>
> Jim
>
> On Tue, 4 Jun 2002, Lai, Wai S (Waisum), ALASO wrote:
>
> > Jim,
> >   I think our proposal to add some text in the requirements doc for
> > BC model is in the same spirit as in Section 4 "Solution Evaluation
> > Criteria" of this document for solutions supporting DS-TE.
> >
> >   Let me quote again the paragraph in question:
> >     "At the time of writing this document, it is not clear whether a
> >     single model of Bandwidth Constraints is sufficient, which one it
> >     should be and how flexible this model really needs to be and what
> >     are the implications on the DS-TE technical solution and its
> >     implementations. The DS-TE technical solution must specify one
> >     default bandwidth constraint model which must be supported by any
> >     DS-TE implementation."
> >
> >   Regarding the first sentence, we have now some new information on
> the
> > implications of the BC models, which is contrary to what is stated as
> > "it is not clear".
> >
> >   More importantly, the second sentence in above text only says that
> > one default needs to be specified *without going into the specific
> > selection criteria*.  We believe that some criteria to be considered
> > include at least:
> > (1) performance under normal conditions versus service protection
> >     and isolation capability under overload (as stated in my previous
> >     email)
> > (2) signaling load processing requirements (as stated in the email by
> >     Rudiger Geib)
> >
> >   As I explicitly stated in my previous email, we fully agree that the
> > requirements doc is not the place to resolve what the default model
> > should be.  Thus, we have no objection to continuing this discussion
> > in the context of draft-ietf-tewg-diff-te-proto-00.txt, but see a
> > need/value in identifying criteria and referencing relevant studies
> > in the requirements document.
> >
> > Thanks, Wai Sum.
> >
> > -----Original Message-----
> > From: Jim Boyle [mailto:jboyle@pdnets.com]
> > Sent: Monday, June 03, 2002 10:15 AM
> > To: Ash, Gerald R (Jerry), ALASO
> > Cc: Lai, Wai S (Waisum), ALASO; te-wg@ops.ietf.org
> > Subject: RE: WG last call: draft-ietf-tewg-diff-te-reqts-04.txt
> >
> >
> >
> > Jerry - it is already specified in the requirements document that the
> > bandwidth constraint model must be specified in the technical solution
> > document:
> >
> > 	"The DS-TE technical solution must specify one
> >    default bandwidth constraint model which must be supported by any
> >    DS-TE implementation"
> >
> > How = IETF process, Where = TEWG.  Do we really need to state that?
> >
> > As for making comparisons between models in the draft, I don't think
> > it's
> > called for.  I think making references to documents which describe
> them
> > is
> > also something that isn't necessary in the requirements document.  As
> > for
> > adding some text as to the decision must be made on "hard information"
> -
> > I
> > see that as a no-value addition to the document.
> >
> > What objection do you and Wai have to having this discussion in the
> > context of draft-ietf-tewg-diff-te-proto-00.txt ?
> >
> > Jim
> >
> > On Mon, 3 Jun 2002, Ash, Gerald R (Jerry), ALASO wrote:
> >
> > > > The discussion on what should be the default bandwidth constraint
> > > > model should be done in the context of the solution draft.
> > >
> > > This should be stated as a requirement in Section 3.3 of the
> > requirements draft.
> > >
> > > > The paragraph you quote makes it clear that the requirements draft
> > leaves that
> > > > discussion squarely with the technical solution.
> > >
> > > Nowhere in Section 3.3 of the requirements draft is it stated how or
> > where the technical solution will be decided.  It should be stated as
> a
> > requirement in Section 3.3 that "the default BC model will be decided
> in
> > the context of the technical solution draft."
> > >
> > > > I don't see a need for any text revision of the requirements draft
> > before
> > > > sending it on to the IESG.
> > > > Anyone else have any comment?
> > >
> > > Yes.  An additional requirement should be added in Section 3.3:
> > > "the default BC model must be based on available hard information,
> > such as analysis given in [forthcoming lai-id] [other relevant
> > references]."
> > >
> > > Also, Wai Sum's suggested short explanation of the essence of his
> > analysis is highly relevant to Section 3.3, and shouldn't be rejected
> > out of hand.
> > >
> > > Jerry
> > >
> >
> >
> >
> >
>