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Re: few comments on draft-ietf-tewg-interas-mpls-te-req-01.txt
At 07:20 PM 12/6/2003 -0800, Yakov Rekhter wrote:
> > > > > The solution SHOULD provide an option for the Head-End LSRs to
> > > > > > if re-optimizing or not should there exist a more optimal
> > between
> > > > > > the Head-End and the Tail-End LSRs.
> > > > >
> > > > > Good point on the option of traversing the same path... So we
> > will make
> > > > > our original point as a
> > > > > special case to your proposed wording above by adding the
> > > > >
> > > > > "In the case of an identical set of traversed path, the
> > > > > provide an option for the Head-End LSRs to control if
> > > > > re-optimizing or not should there exist a more optimal path in one
> > of the
> > > > > transit ASes along the inter-AS TE LSP path."
> > > >
> > > >Why do you need this "special case" ? In other words, why the text I
> > > >proposed is not enough ?
> > >
> > > Well, in your proposed text, it is not specified if this HE LSR/TE
> > > the HE/TE of the inter-AS LSP or just
> > > a segment of the inter-AS LSP. Our requirement is to have the HE
> > > the inter-AS TE LSP, not just the mid point LSR of
> > > segment LSP to have the control if re-opt or not in the case that
> > > TE LSP needs to traverse along the same AS path.
> >Are you saying that your requirement applies only when the new and the
> >old path traverse the same set of ASs ?
> Oh no,,, this is just one of the applicable cases.
I still don't quite understand what it adds...
I should probably clarify this a bit then... Looking at the following
-----------> <------ AS3--------->
PE1 - P1 - P2 - ASBR12 <----> ASBR21- ...- ASBR23 <--------> ASBR32 - P3...-PE4
| | |
P3 -------ASBR14 <-----> ASBR41-...- ASBR43 <---------> ASBR34
<------ AS1 ------------------> <--------- AS4
----------> <------ AS3------->
If the original inter-AS TE LSP is built along AS1 - (via ASBR21) AS2 -
AS3, then my thinking is that there maybe two cases where a more optimal
path is available to the HE LSR of the inter-AS TE LSP:
Case 1. Still follows AS1/AS2/AS3 but a more optimal path is available
between ASBR21 and ASBR23 ( or a different ASBR from ASBR21 or ASBR23 in
the same AS2, (not shown in the diagram though))
Case 2. A more optimal path is available along AS1/AS4/AS3 (different path
from the original).
So in either of above cases, we would like to provide an option (SHOULD)
for PE1 in AS1 (HE of the inter-AS TE LSP) to control if re-opt or not.
Your proposed wording would cover case 2, however I don't think it is
adequate or explicit enough to address requirement for case 1. So I'd like
to have a more explicit statement which is in my proposed wording as a 2nd
> If so, I would like to post -03 to reflect what we've discussed up until
> now by this weekend so that I can get the last call process started...
> Thanks once again for your input.