Tuesday, August 17, 2021

OSPF Large area vs many areas.

We have WAN network of about 30 branch offices. Currently they have a main L2 link and LTE backup. All branch offices live in single OSPF area which has three ABRs, two for L2 links and one for LTE links. All links are network type point to point. Each branch office has 3-4 local /24 networks which, for historical reasons, cannot be aggregated. (BO addressing is like this: 10.[a-d].x.0/24). The number of branch offices is slowly increasing.

Everything seems to be working OK. Changes in the network are propagated in decent time . But the change is coming, we are going to build a backup data center and get redundant L2 links for most of the branch offices. Diagram here

Now I have a question. Do I keep current design or change to an area per branch office? I have seen this approach on the Internet and I am not sure it this makes sense. What are implications and limitations? My knowledge about OSPF internals is not deep enough and Cisco design guides do not help much.

I hope this time it will not be to trivial question for the mods and I will not have to move to /homenetworking or sth.



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