[c-nsp] filter LDP bindings

[Saku Ytti]

On (2008-08-13 20:38 +0200), Oliver Boehmer (oboehmer) wrote:

> well, this dependency on what other LDP neighbors send is not really
> in-line with the independent control mode LDP operates in, so the
> implementation might not be straight-forward.

I think we have misunderstanding here. All boxes would 'stupidly'
accept and readvertise everything they get, no additional states
here, plain 'ol ios behaviour without LDP ACL.
But per node, you'd tell the nodes not to generate label, except
for their loopback.
End result would be, that you'd only have loop0̈́s in each MPLS 
spakers LIBs, without any ACL/prefix-list maintenance overhead.

> well, "interfaces" would also cover connected /30 or /31s, something you
> usually don't want to advertise labels for?

You'd replace the 'interface' with loop0 or loopX, which ever you use
for labeled destination.

> But wouldn't a (prefix) ACL be enough to cover most cases? Generally,
> loopbacks are allocated from one or more prefix ranges, so ACLs could be
> rather static?
 
Yes, both can easily accomplish same goal, just bit additional admin overhead,
while the true application in virtually all cases is, to generate label for
single loopback interface. And actually we would have probably used 'your'
way, had it been available when we wanted to implement it, instead of doing
advertisement ACLs.

-- 
  ++ytti