OSPF on ACI

[m1xed0s]

If I remember correctly, when configuring OSPF L3Out in ACI, the default Area# and Area type are 1 and NSSA respectively. Majority of the cases I ran into is ACI fabric would be running as the CORE in DC. So I would have to change them to 0 and standard area. I wonder if there is any theory/intent behind the scene on why those two are chosen as the default values? Or maybe I have been doing it wrong all these years?...

[RedNectar · Accepted solution]

Hi @m1xed0s ,

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If I remember correctly, when configuring OSPF L3Out in ACI, the default Area# and Area type are 1 and NSSA respectively.

Correct

Majority of the cases I ran into is ACI fabric would be running as the CORE in DC. So I would have to change them to 0 and standard area.

Correct again

I wonder if there is any theory/intent behind the scene on why those two are chosen as the default values? Or maybe I have been doing it wrong all these years?...

Well. It probably goes back to ACI v1.1 (or another VERY early version) when the ONLY OSPF area type supported was NSSA, so necessarily could NOT be area 0.

So in v1.1 (approx) it made sense to make the default NSSA, and area 1 is as good as any when it can't be 0

I suggested to CIsco some time ago that the default be changed from NSSA to Regular, but this suggestion, like the many others I have put forward have been summarily ignored.

[m1xed0s]

Thanks! Good info for me.