Dears;
This post explains when to implement multi-area OSPF.
Lets say you are in a campus network where there are many L3 devices. OSPF is originally designed for low CPU routers. Simply, when there are many routers in the same area, an area flapping may happen. If area flapping happens, theoretically all routers in the area must recompute the topology. This is a big interruption in a campus network until the SPF computation is done again.
That is where multi-area OSPF comes into the image. Multi-area OSPF solves the above problem. This will divide routes into multiple places. That means all different areas will communicate through ABR (area boarder router). It will minimize the percent of recomputation in the entire campus network.
I will continue about multi-area OSPF in PART 2. stay tuned
