[c-nsp] ospf between me and customer - design ?

[Justin M. Streiner]

>> For various reasons, it's been decided to run OSPF between me and a
>> customer network.  However, since their gear is outside my
>> administrative control, I want to make sure I only get the networks I
>> expect from them and they only get a default route from me.

Having been down this road before (not my choice), I would stay very far 
away from doing OSPF with customers, even if you manage the router(s) at 
the customer location(s).  OSPF was not initially designed to allow LSAs 
to be filtered.  The possibility of unplanned LSAs still managing to creep 
into your LSDB is just too high.  This one is worth beating people into 
submission if the decision was made on some political basis that's way 
outside the scope of cisco-nsp :-)  It's been my experience that 
filtered redistribution between areas or separate OSPF processes just 
doesn't work that well.

As other people have mentioned, perhaps BGP would be a better choice here, 
especially since you're just sending default and accepting a few networks 
from the customer.  Filtering is much easier, and this is a pretty common 
SP-to-customer design.

If you're doing a primary-failover design where traffic goes over link B 
only if link A is down, then floating static routes also work well as long 
as you but the static routes in correctly so they disappear when the link 
goes down.

If you need to use a link-state protocol for this, consider another one, 
like EIGRP or IS-IS, though I would consider this to be a next-to-last 
resort.

jms