why do you need a loopback when using ospf?/ multiarea ospf LSA diffrent from same area LSA ?

[Joseph W. Doherty]

"why do you need a loopback when using ospf?"

You don't.  However, loopbacks are commonly used as they are stable, i.e. they don't go up and down based on media changes.

"multiarea ospf LSA diffrent from same area LSA"

Yes.

You can find different explanations for the different LSA types, if you search the Internet for such.  For example: https://networklessons.com/ospf/ospf-lsa-types-explained

[Georg Pauwen]

Hello,

not really sure what you are asking. You don't need a loopback for OSPF, but a loopback is typically used because OSPF choses the IP address of that loopback for it's router ID. If there is no loopback, OSPF will chose the highest configured IP address for the router ID.

[MHM Cisco World]

using Loopback is useful for load balance in multi area.

[Joseph W. Doherty]

"using Loopback is useful for load balance in multi area."

Could you further explain, how so?