Question on flushing AS-external LSAs

[Mukesh Hira <mhira at LUMINOUS.COM>]

Hi,

I'm looking for an answer to how OSPF would behave in the following scenario.

Say an ASBR advertised some AS-external LSAs and then crashed. Now, OSPF (at least v2) only allows a router to flush LSAs that it originated. Given that the router that originated these AS-external LSAs has crashed, would these AS-external LSAs stay in the Link State Database of all routers in the OSPF domain for upto an hour until they get aged out? Would these not be flushed?

Let's assume that the forwarding address in the AS-external LSAs was set to the IP address of one of the interfaces on the ASBR. When SPF is run after the Router LSA (or Summary LSA if the ASBR is in another area) to this IP address gets flushed, would this forwarding address not being reachable anymore cause all these AS-external routes to be deleted from the routing table of all nodes?

What if this ASBR that crashed was one of two ASBRs advertising the same AS-external routes, and has the higher router ID, so that the other ASBR flushed its AS-external LSAs. When this ASBR with higher router ID crashes, what triggers the other ASBR to re-inject its AS-external LSAs into the network? Would the event of forwarding address for the LSAs heard from the other ASBR not being reachable anymore trigger it to inject its own AS-external LSAs in the network?

Thanks in advance
- Mukesh