Hi Rene,
I have several questions :-
1 - Can we have ABR between sub areas or the ABR must be only between backbone area and sub areas ?
2 - Can we have the ASBR in sub areas or the ASBR must be only in the backbone area ?
3 - What is the different between saves address space and used address space that you mentioned in the advertisement of loopback interface addresses ? I did not understand that and I have some ambiguity at this point ? can you explain it to me in detail please ?
4 - what is the benefit of sharing information with OSPF hello packets like Router ID, neighbors, DR and BDR IP address, router priority ?
thanks.
Hussein Smaeer