Subject: RE: Does MPLS Require L3 Routing Table ?

From: Juha Heinanen <[email-masked]>
Date: Thu, 19 Apr 2001 15:16:16 +0300 (EEST)

Javier Antich writes:

 > Yes, that is true, but how would the core router choose the right label
 > towards the right next hop if it receives a label assignment from two or
 > more neighbours for the same route?

if an lsr receives two advertisements for the same destination, it would
pick one of them, for example, based on the length of the "traceroute" in
the message and it could remember the other one.

-- juha

---

From: Javier Antich <[email-masked]>
Date: Thu, 19 Apr 2001 09:36:33 +0200

> > How would you get the LSPs  to be setup "automatically between
all your edge
	> > routers" without having any L3 routing information in the core?

	>i'm not an ldp expert, but i assume that using the du mode, each
egress
	>router can advertise an lsp to itself to all its neighbors and so
on.
	>thus eventually every router in the system would have a path to
every
	>egress router.  this assumes that each router adds itself to the
	>advertisement in order to cut the loops.

Yes, that is true, but how would the core router choose the right label
towards the right next hop if it receives a label assignment from two or
more neighbours for the same route? That might happen, and the core router
must use its IGP routing table to select the right label and right
nexthop/outgoing interface.

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Javier Antich Romaguera
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> -----Mensaje original-----
> De:	Juha Heinanen [SMTP:[email-masked]]
> Enviado el:	jueves 19 de abril de 2001 4:31
> Para:	[email-masked]
> CC:	[email-masked]; [email-masked]
> Asunto:	Re: Does MPLS Require L3 Routing Table ? 
> 
> 
>  > How would you get the LSPs  to be setup "automatically between all your
> edge
>  > routers" without having any L3 routing information in the core?
> 
> i'm not an ldp expert, but i assume that using the du mode, each egress
> router can advertise an lsp to itself to all its neighbors and so on.
> thus eventually every router in the system would have a path to every
> egress router.  this assumes that each router adds itself to the
> advertisement in order to cut the loops.
> 
> -- juha