The MPLS WG Archive

[Paul Billinghurst <pbillinghurst@extremenetworks.com>]

Can anyone verify or correct my understanding of the following scenario. The
MPLS domain is LDP, configured as downstream unsolicited. When I use the
term ABR - I am referring to the ABR of the stub or NSSA area unless I state
differently.

A router internal to a stub or NSSA potentially will only have an
advertisement from ABRs for the default route. If routers internal to the
stub area wish to reach destinations for which they do not have a FEC entry
then they will have to send the data unlabelled to the ABR. Is that correct
?

Is there any mechanism short of static routes which would allow the stub
area router(s) to use an LSP to the default route which 
I assume would be pretty dangerous to use because if there is a default
route across the OSPF domain and that LSP is used, then all data from stubs
or NSSA would use that LSP whereas the ABRs could make far more intelligent
routing decisions if they were not simply swapping labels for the default
route. 

If use of a default route LSP is possible, is there a mechanism which would
allow an ABR, to pop the label instead of swapping and making that
"intelligent decision" if indeed it does have default route LSP which
extends beyond itself into the domain, but it would be better served sending
the data on an LSP for which it has a more direct FEC entry.  

Thanks

Paul