[c-nsp] filter LDP bindings

[Oliver Boehmer (oboehmer)]

Saku Ytti <mailto:saku+cisco-nsp at ytti.fi> wrote on Wednesday, August 13,
2008 7:23 PM:

> On (2008-08-13 17:29 +0200), Oliver Boehmer (oboehmer) wrote:
> 
>> well, an LSR needs to allocate labels also for other nodes'
>> loopbacks, so this alone will not be enough ;-)
> 
> All boxes would advertise everything they get, but only generate
> loop0. 

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.

>> However, IOS now has a label allocation filter
>>
(http://www.cisco.com/en/US/docs/ios/mpls/configuration/guide/mp_ldp_all
>> oc_filter.html) having a "allocate global host-routes" shorthand to
>> only allocate labels for /32s (or uses a prefix-list for more
>> granular control)..
> 
> Interface would be nice short-cut, as it's probably most typical
> situation that you only want labels for loop0.

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

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?

	oli