For all answers, show how you derived your answer, including diagrams and all formulas used. Just providing the end-result gets NO credit.

Network Performance

Assume propagation speed is 2 * 10⁸ m/sec for all problems.

Suppose we have a single link between sender and receiver. The transmission speed (R) is 10 Mbps and packets are 1500 bytes. Link distance is 50m.

What is the transmission delay (d_trans) on the link? Show formula.

What is the propagation delay (d_prop) on the link? Show formula

How many packets can the link transmit per second? Show formula

Suppose we extend the network above with three links and two routers: Sender ----> Router1----->Router2----> Receiver. The first and third links have the same properties as above. The middle link has a transmission speed of 50Mbps and a distance of 100km. Assume queuing and processing delays are negligible.

What is the total end-to-end delay? Show formulas.

What is the effective end-to-end throughput on this network? Why?

Web and HTTP

Assume a web browser caches web pages locally on a user machine. Explain in your own words how web caching impacts HTTP traffic sent to the web server. Be concise! Illustrate using a diagram. Cite any references you used to come up with your answer.

Explain how caching improves network performance. What potential negative impacts does caching have?

UDP Checksums

What is the 1s complement of the sum of the following 8-bit bytes (show all calculations):

01010011

01100110

01110100

With 1s complement, how does the receiver detect errors? Is it possible that a 1-bit error will go undetected? What about a 2-bit error?