If you have a service that uses a specific port, and you have multiple computers on the same ip addess, how is this handled? Should the service specify to which computer on the ip address the information should be send? What if both computers on the same ip use the same service, but request different information?
Also, if a client is on a dynamic ip, how should the service detect that the ip has been changed, but the client (and the session) is the same? Should clients identify themselves for every request (much like cookies over http)?
I don't think I fully understand what you've said. There is no way that multiple computers will be on the same IP, this is not how the internet works.. There are protocols which hadels such things.
Did you mean that you're a server and multiple computers try connect to you?
If so, you listen in a port and when you get a connection you open a new thread for the service of that computer and the main loop still listening
Multiple clients from same IP