OSPF Area and Interface Authentication

[UncleJP]

What is the point of using area authentication when the authentication configuration on the interface overrides any area authentication that is configured?

Ex. if message-digest authentication is configured for the area, but null authentication is configured on the interface. 

Best regards,

Jason

[balaji.bandi · Accepted solution]

The difference between the two is that for interface authentication you only enable authentication for one link rather than for the whole area. Additionally, if you wanted to only do one type of authentication for certain links and then use a different type (plain text or MD5) then you could use interface authentication.

Configuring Area authentication will enable authentication for the entire area. This is to save some configuration.

Configured at the interface level will override the area configuration command.

configuration example :

https://community.cisco.com/t5/networking-documents/ospf-authentication/ta-p/3131640

[Abderahman-K]

@balaji.bandi, sorry to bring an old post back to life. Is area authentication command required on both switches to form an adjacency? 
Thanks!

[Joseph W. Doherty]

I recall (?) area authentication is an area wide attribute that all devices using that area need to agree on.  (Much like same area routers need to agree on the area number.)

When enabled, same area authentication routers, sharing a link, need to use the same password, but the password can be null.