Assignment 1

Due Wednesday, February 3, 2016 via sakai prior to 6:25pm

Introduction

Please answer the questions precisely and concisely. Every question can be answered in one or at most a few sentences. I will not have the patience to read long paragraphs or essays and you may lose credit for possibly correct answers.

Reading

Text: Chapter 1, pages 1-47 (sections 1 through 1.4.4).
Questions 1 through 3 are from the text.
Brief History of the Internet , Barry M. Leiner, Vinton G. Cerf, David D. Clark, Robert E. Kahn, Leonard Kleinrock, Daniel C. Lynch, Jon Postel, Larry G. Roberts, Stephen Wolff. October 15, 2012, Internet Society.
Questions 4 & 5 refer to this paper.

Questions

  1. [Kurose & Ross text: Page 68, question R11.]
    Suppose there is exactly one packet switch between a sending host and a receiving host. The transmission rates between the sending host and the switch and between the switch and the receiving host are R1 and R2, respectively. Assuming that the switch uses store-and-forward packet switching, what is the total end-to-end delay to send a packet of length L? Ignore the queuing, propagation delay, and processing delay.)
  2. [Kurose & Ross text: Page 72, question P2.] Equation 1.1 (page 24; dend-to-end = N(L/R)) gives a formula for the end-to-end delay of sending one packet of length L over N links of transmission rate R. Generalize this formula for sending P such packets back-to-back over N links.
  3. [Kurose & Ross text: Page 72, question P7.] In this problem, we consider sending real-time voice from host A to host B over a packet-switched network (VoIP, voice over IP). Host A converts analog voice to a digital 64 kbps bit stream on the fly (64 kilobits per second; a kilo is 103, not the base-2 Kilo of 1024). Host A then groups the bits into 56-byte packets. There is one link between Hosts A and B; its transmission rate is 2 Mbps (megabits per second; M = mega = 106) and its propagation delay is 10 msec (1 msec = 10-3 sec). As soon as Host A gathers a packet, it sends it to Host B. As soon as Host B receives an entire packet, it converts the packet's bits to an analog signal. How much time elapses from the time a bit is created (from the original analog signal at Host A) until the bit is decoded (as part of the analog signal at Host B)?
  4. What is meant by open architecture networking? [from the Brief History of the Internet paper]
  5. The Internet (ARPANET) was initially envisioned to have one protocol for applications to use to transport data. Later, two were created: TCP and UDP. Why did the designers feel a need to create two transport protocols? [from the Brief History of the Internet paper]