Re: Last Call: Traffic Engineering Extensions to OSPF Version 2 to Proposed Standard

[Yakov Rekhter <yakov at juniper.net>]

Suresh,

> > > My recommendation against using this draft as the basis for 
> > > building further TE-extensions to inter-area and mixed networks
> > > was in the context of OSPF Autonomous System (AS). I also 
> > > mentioned the draft has scalability limitations in extending this 
> > > to inter-area and mixed networks -  also in the context of OSPF AS.
> > > 
> > > Without going into the details of the "Multi-area MPLS Traffic
> > > Enginering" draft - The work cited in this draft as going on to 
> > > address multi-area TE is in the MPLS signalling context, not in 
> > > the OSPF.
> > 
> > As I said in my previous e-mail quite a few scenarios described in
> > draft-kompella-mpls-multiarea-te-03.txt are supported with the TE
> > extensions that are subject to this Last Call. That is precisely
> > while quite a few scenarios in the "Multi-area MPLS Traffic Engineering" 
> > draft do not require any additions to what is already defined
> > in the katz-yeung draft. 
> > 
> > Yakov.
> 
> Yakov,
> 
> Yes, quite a few scenarios described in kompella-mpls-multiarea-te draft 
> are supported with single-area TE extensions and do not require any 
> additions. And, katz-yeung draft proposal will suffice for single-area 
> TE extensions. 

Good. So we are in agreement that the katz-yeung draft can support
both single area and multi-area TE.

> katz-yeung draft does not cover dissemination of inter-area TE info
> (which I was refering to as *inter-area OSPF-TE*). Neither does the 
> draft claim to do so. 

That is correct too. 

> Inter-area OSPF-TE is a scenario described in 
> kompella-mpls-multiarea-te for faster convergence in LSP computation.

I am not sure which scenario you are referring to. But anyway, this
is outside the scope of the present discussion...
  
> In this context - my recommendation to not use katz-yeung draft as the 
> basis to extend to inter-area OSPF-TE was because of its scaling 
> limitation.

And my recommendation is exactly the opposite - start multi-area TE
with what is already in the katz-yeung draft, gain some operational
experience with it, and then improve this, *if necessary*, based on 
the experience. But anyway, this is outside the scope of the present
discussion...
  
> Neither katz-yeung nor kompella-mpls-multiarea-te drafts address mixed
> networks. katz-yeung draft has limitations with flooding disruption 
> and topology isolation in a mixed network - both intra-area and 
> inter-area. This was another reason why I recommended to not use 
> katz-yeung draft as the basis to extend to inter-area OSPF-TE.

To avoid any confusion I would suggest to add the following to
the katz-yeung draft:

  It is an explicit non-goal of the solution described in this
  document to address all possible (as well as impossible)
  requirements. Therefore, the solution described in this document
  is clearly not a perfect solution, and as such doesn't quality
  for being a LTSFGTC (Long Term Solution For Generations To Come).
  Work on the perfect solution (aka LTSFGTC) is in progress, and is
  expected to be published in RFC100000.

Yakov.