=?gb2312?B?u9i4tA==?=:RE: OSPF inter-AS extensions for GMPLS (RFC5392) questions

MachChen 55527 <mach@huawei.com> Mon, 09 March 2009 13:22 UTC

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From: MachChen 55527 <mach@huawei.com>
Subject: =?gb2312?B?u9i4tA==?=:RE: OSPF inter-AS extensions for GMPLS (RFC5392) questions
To: Fabien Verhaeghe <fabien.verhaeghe@marben-products.com>
Cc: 'Adrian Farrel' <adrian@olddog.co.uk>, ccamp@ops.ietf.org
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Hi Faibien,

Sorry about the confusion.


----- 原邮件 -----
发件人: Fabien Verhaeghe <fabien.verhaeghe@marben-products.com>
日期: 星期一, 三月 9日, 2009 下午3:41
主题: RE: OSPF inter-AS extensions for GMPLS (RFC5392) questions
收件人: 'Adrian Farrel' <adrian@olddog.co.uk>uk>, ccamp@ops.ietf.org

> Hi Adrian,
> 
> See in-line
> 
> > Hi Fabien,
> > 
> > > Sorry to come a little late on this but I have a question on 
> inter-AS
> > > extensions RFC5392 (also applicable on ISIS extensions).
> > > In section 4:
> > > " Only some essential TE information for the link needs to be
> > >   advertised; i.e., the Link Type, the Remote AS number, and 
> the Remote
> > >   ASBR ID."
> > >
> > > First what does "remote" mean here? is it remote in the context 
> of the
> > > proxied link or in the context of the Router?
> > > i.e.
> > >
> > > RouterA in AS1 ------TE Link------ RouterB in AS2
> > >
> > > I guess it is in the context of the link. That is in LSA 
> generated by
> > > router
> > > A for B->A link (proxied) we put AS1 and routerA ASBR Id. Is that
> > correct?
> > 
> > Yeah, you could say "in the context of the router." Or even "in the
> > context
> > of the IGP instance". Since the IGP will only be running in one 
> AS, the
> > advertising router is talking about the IDs of the "other" AS and 
> ASBR.> 
> 
> Sorry but I am still a little bit confused.
> Router A generates 2 LSAs for a TE link between A and B.
> One for A->B direction and one for B->A direction (because B is in a
> separate IGP).
> Are you saying that in both LSAs the remote AS number sub TLV is 
> set to
> Router A's AS?

No, for A->B direction, the remote AS number sub_TLV is set to Router B's 
AS, and for B->A direction, it is set to Router A's AS.

I think it more accurate to say "in the context of the router or proxied 
router" or even "in the context of the IGP instance or proxied IGP intance" 
:-)

For me, "in the context of the link" is also OK.


> 
> If yes what I don't get is how other routers in this AS knows which 
> LSAcorresponds to A->B direction and which one corresponds to B->A 
> direction.
> That is why I thought "remote" in the text mentioned in my first email
> refers to the "link context". Then both LSAs would contain 
> different remote
> AS/ASBRId so that we can tell which one corresponds to each direction.
> 
Correct.

> Please let me know if I miss something...
> 
> Thanks
> Fabien
> 
> 
> 
Best regards,
Mach