Q & A on TCP and Path Selection Q: It is my understand that when a connection-oriented service is established, it doesn't change the path even if routing tables change. I.e., like telephones. However, TCP is providing a connection-oriented service. At the same time, I think, it does change routes all the time. Another example is the cellular phones. they are connection-oriented service, but they change their routing as phones move from one cell to another cell. Am I right? What is the difference between these three situations? Please advise. A: You are confusing the service offered with the internal implementation. TCP provides a good example of the distinction because it offers a connection-oriented service to applications, but uses a connectionless underlying protocol (IP) to exchange segments. Thus, although an application can form a TCP ``connection'' to another application, only the TCP modules on the sending and receiving endpoints are aware that a connection exists. Routers between the endpoints are free to change routes at any time.