[c-nsp] ldp-igp

[Oliver Boehmer (oboehmer)]

Mark Tinka <> wrote on Monday, November 24, 2008 03:05:

> On Monday 24 November 2008 03:41:07 Marlon Duksa wrote:
> 
>> Thanks Mat. That helps a lot.
>> But is there any way to select IP instead MPLS for
>> forwarding witout ACLs. Say that route x.x.x.x is
>> received by OSPF and LDP (FEC mapping). Is there any way
>> to enable forwarding only on IP and not MPLS for that
>> particular route without ACLs. For example, changing
>> preference (or administrative cost) of OSPF to a lower
>> value than LDP - something like that but on a per
>> interface basis. Or changing preference of LDP to a
>> higher value on a global basis. Juniper for example can
>> change preference of LDP.
> 
> From your initial e-mail I could tell you were trying to do,
> in IOS, what JunOS does, i.e., treat LDP and RSVP as route
> sources and install forwarding entries into the routing
> table with preferences (administrative distance in IOS),
> e.g.,:
[...]
> 
> Aside from what others have already mentioned in this
> thread, I'm not sure IOS treats these label distribution
> protocols as routing protocols.

No, it doesn't. To put is simple: if IOS installs a RIB entry and it
finds a FEC binding in its LIB for the respective next-hop/oif, it uses
it. If you don't want this to happen (for whatever reason), you can
either filter the outgoing LDP advertisement downstream, or filter the
LDP advertisement on the node itself (Inbound label filtering, "mpls ldp
neighbor x.x.x.x labels accept <acl>").

Marlon: What are you trying to achieve? If you don't want to add a label
to packets over a given interface, why did you enable LDP on it in the
first place?

	oli