great explanation -
another trick you could do on R2 & R3 is to suppress the FA - say you filtered the 192.168.45.0 0.0.0.255 network into area 0 via an area filter command on R2 & R3 you could then subsequently on R2 & R3 do the following. (in doing area filtering of the 45.x network into area 0 - R1 will not be able to recurse to the 5.5.5.5 network and thus not install 5.5.5.5 in the RIB) to fix this you could then do this on the ABR’s
R2 & R3
ip prefix-list AREA_1_ROUTES deny 192.168.45.5/32
ip prefix-list AREA_1_ROUTES permit 0.0.0.0/0 le 32
router ospf 1
area 1 filter-list prefix AREA_1_ROUTES out
area 1 nssa translate type7 suppress-fa
adding the always keyword to that command on either router would force a router to always do the translation and thus it would be in both the control & data plane for the 5.5.5.5. traffic from R1. The FA is then suppressed from the advertisement and R1 could correctly recurse to the 5.5.5.5 network via R2 or R3 directly.
great post.
thanks
Ray.