Activity 1 Multiplexing

I want to explore the interface between the UDP/TCP layer and the application layer protocols. When you look at network layer protocols on down you might think to yourself that they would be fine to interface your program to. After all you are passing information over either the network or link layer between two stations. But those protocols are missing something that would be very valuable. Lets use the postal service as an analogy. Please answer the following questions: When I address a letter for someone what part of the address does the mailman need to get the letter from your house to the destination? What part of the address do they not care about? Who needs the unneeded part of the address and why?

Activity 2 User Datagram Protocol (UDP)

I feel bad for UDP. It is almost never mentioned and TCP almost always is mentioned in the same breath as IP. You might think that TCP and IP are joined at the hip. That is not the case. UDP is also a user of IP services. Along with TCP it is one of the lowest layer protocols that the application programmer will probably be dealing with. If I tell you UDP provides a connectionless service can you tell me: What would you not see in the UDP packet header? Why would I use UDP if I have TCP available?

Activity 3 TCP Aspects

TCP is complex and for good reason. You have to admire a design that can provide such a demanding service (connection oriented) over all kinds of networks with their different quality of services (QOS). What aspects of the TCP design promotes stability in the Internet? How do these aspects effect the real time services such as streaming media?