[c-nsp] filter LDP bindings

[Saku Ytti]

On (2008-08-14 09:41 +0200), Oliver Boehmer (oboehmer) wrote:
 
> Well, I think this is the catch: In independent control mode, LDP does not "re-advertise" something like a distance/path-vector routing protocol does, it advertises its local bindings. So to implement a "re-advertise" behaviour, one would need to change the local binding behaviour to "only allocate (and advertise) a label for a remotely-learned IGP prefix x/y if you already received a remote LDP binding for this prefix or if you're the egress LSR for this FEC".. This is ordered control, something IOS only implements for cell-mode MPLS (i.e. ATM).

> > End result would be, that you'd only have loop0̈́s in each MPLS
> > spakers LIBs, without any ACL/prefix-list maintenance overhead.
> 
> agreed. But I still see challenges getting this right in independent control mode.. Am I missing something?

Perhaps I mistook that it would be easier than in reality it is, to
determine this information from LIB. I assumed that creating bindings
perfectly normally for data received over LDP session is no-problem
and only thing that needs to change, is that in first place, you don't
locally add anything to your bindings, except your Loop0.
 
> I guess so, filtering label allocation is more "natural" and efficient than filtering the advertisement for this very common case..

Yes (more natural than ACL filtering what you advertise out).

-- 
  ++ytti