MMOG networking Architecture - How does it work?

Hey everyone,

I am currently working on a 2D/3D game world mix for a MMO that I want to make with that said - I am curious about how Massively Multiplayer Online Game networking architecture works.

Does it work similar to traditional Server/Client networking architecture found in games such as TF2 or Left 4 Dead?
or is it totally different?

Could someone give me some insight on this?

Thanks,

  • HeadClot