Re: Re: IGP-LDP interaction

From: Spice Sylvia <falsesylvia@yahoo.co.uk>

Date: Thu, 22 Jan 2004 18:06:40 +0000 (GMT)

Cc: mpls-ops@mplsrc.com

Resent-Date: Thu, 22 Jan 2004 14:14:55 -0500

To: richard.james@rogers.com, Eric Osborne <eosborne@cisco.com>, Harpreet Singh <harpreet_singh_2000@yahoo.com>

if the router u mention below, simply looked at range and followed some circuit which let it propogate and do a lookup on "ip Range" using the same patricia tree concepts as ever documented... would it not have to rely on metrics?

where does exact match go then?

PS: hey guess what? the circuit for Carry look ahead (CLA) algos is already there.

In order to advertise a label received for a particular prefix, a router has to have a route in its IGP that is an *exact* match for the prefix.

Here's a question: if a router has a route that is less specific than the prefix in the LDP mapping, but still matches, could it advertise the LDP mapping in that case? So basically doing a longest match instead of an exact match? I understand that most routers need the exact match today, is this because of implementation or is it the standard dictating it?

>
> From: Eric Osborne
> Date: 2004/01/22 Thu AM 07:05:19 EST
> To: Harpreet Singh
> CC: mpls-ops@mplsrc.com
> Subject: Re: [MPLS-OPS]: IGP-LDP interaction
>
> On Thu, Jan 22, 2004 at 02:32:15AM -0800, Harpreet Singh wrote:
> >
> > Can anyone tell me! / refer me to some good pointers on
> > how OSPF interacts with LDP?
>
> They don't really interact, they're two different protocols.
>
> > Specifically in JUNOS, the rouyter does not distribute labels to its
> > LDP neighbors for prefixes that it odes not have in its IGP although
> > it recieved a downstream label for it from another neighbor. Is
> > there some standard for this?
>
> IOS works the same way. The idea with LDP (in non-Martini mode,
> anyways) is that it distributes labels for routes it has in its IGP
> routing table. LDP is not a routing protocol, and does not give out
> reachability information that routing does not also give out.
>
>
>
> eric
>
> >
> > Thanks in advance.
> > HS

1

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Re: Re: IGP-LDP interaction
- From: <richard.james@rogers.com>

The MPLS-OPS Archive

Re: Re: IGP-LDP interaction