After reading about packet and circuit-switching, I've learned that servers maintain multiple connections with a port by passing down an established client connection to a child process; and that all nodes involved in the connection route maintain a connection-id table so packets can be correctly forwarded to the next node.

**I still have a few questions about this though:**

* Do packets need any more header data other than a connection-id number once a connection has been established with another program?
* After a connection is made through, say port 80; does data still go through that port, or has the connection-id established specified a new open port to use for further communications?
* In correspondence with [my question here](https://superuser.com/questions/383763/the-physical-aspect-of-networking-ports); Is there an actual physical separation between different connections? Or is it purely theoretical/virtual?