a) Can I confirm inter-area traffic will be routed towards Area 0 / Area 0 will be the transit network for all inter-area traffic?
b) Consider the diagram below
q2) Going by the rule above that all inter-area traffic must transit Area 0, isn't it totally not efficient for traffic from Area 2 <-> Area 3 to pass through Area 0 via a 100 Mbs link, when Area 2 can reach Area 3 through Area 1 on 1 Gbps link?
q3) How does/will traffic from Area1 go to Area2 ? All inter-area traffic must go through Area0... but.. how ?