1.1 Reliable Byte-streams (Phone Calls)
When you make a phone call, the following steps occur:
- You dial a number.
- The phone system connects to the called party, telling
them there is an incoming call. (Their phone rings.)
- The other party answers the call, or, in the case of a
computer network, refuses to answer the call.
- Assuming the other party answers, the connection between
you is now a duplex (two-way), reliable (no data lost),
sequenced (data comes out in the order sent) data stream.
- You and your friend may now talk freely, with the phone system
moving the data (your voices) from one end to the other.
From your point of view, you have a direct end-to-end
connection with the person on the other end.
The same steps occur in a duplex reliable computer networking connection.
There is considerably more overhead in setting up the communications,
but once it’s done, data moves in both directions, reliably, in sequence.