A new architecture, with N layers, is proposed. User application at the top layer generates a message of M bytes. At each layer, an H bytes header is added. The second layer of that architecture also adds T bytes trailer. In this architecture, the message M is not divided into smaller packets at any layer.  What is the size of the final message (in bytes) transferred by the lower layer? If we consider the headers and trailers to be an overhead, what is the percentage of such overhead to the total size of the final message

Skype is a well‑known VoIP system used not only for peer‑to‑peer conversations but also for audio and video conferencing involving three or more callers. Assume a video conference with a central server on Skype has N callers, and each caller generates a constant data stream at rate r bps. How many bits per second does the call initiator need to send?  How many bits does each of other N‑1 callers need to send?

The message to be sent from source to destination is 4000B.  The link MTU's from source to destination are 1500, 1000, and 750. If we  DO NOT use Path MTU, what are the respective fragment sizes to be reassembled? If we DO use Path MTU, what are the respective fragment sizes to be reassembled? Remember, assume that the L3 and L4 headers have length=0.

We have seen that Internet TCP sockets treat the data being sent as a byte stream but UDP sockets recognize message boundaries. What are one advantage and one disadvantage of byte-oriented API versus having the API explicitly recognize and preserve application-defined message boundaries?

While developing a reliable transport protocol, early versions of the protocol discussed in class used a NAK message, sent by the receiver to the sender to indicate a packet was not correctly received. This kind of message, however, is not found in further protocols, like GBN, SR or even TCP. Why not? In other words, why don't these protocols provide a way to signal to the sender that the received message was received with an error

Provide a succinct outline of the pros and cons of using connectionless protocols as an alternative to connection-based protocols as an alternative to connection-based protocols.

3. Consider the M/M/1 queue discussed in class. Assume that packets arrive to a queue with average arrival rate A [pkts/s]. The average service rate of the queue is denoted by u [pkts/s]. (a) Write expressions for: (i) the mean time between packet arrivals to the queue, i.e., the average inter-arrival time; and (ii) the mean service time, i.e., the average time needed to transmit a packet onto the outgoing link. (b) Let N denote the number of packets in the system in steady-state. Suppose A = 850 and u 1000. Find the smallest value of B such that P(N > B) < e = 10¬4. Hint: Use MATLAB or some other computational tool (you could even use an Excel spreadsheet) to test different values of B. 4. Consider the M/M/1 queue from Problem 3. (a) Find an expression for E[N], i.e., the average number of packets in the system in steady- state. For the values of A and µ specified in Problem 4(b), compute the value of E[N]. What happens when A→ µ? (b) Find an expression for Var[N], i.e., the variance…

The token bucket algorithm is a popular method for traffic shaping. A computer uses a token bucket with acapacity of 400 megabytes (MB) and a rate of 10 MB/sec. The computer continuously generates20 MB/sec for transmission from time 0. Assume the bucket’s water level is 200 MB at time 0.1a. How long will it take to send 1000 MB? Show the steps.1b. Draw a figure showing how the bucket’s water level evolves

Suppose Alice and Bob are going to communicate using AES in CBC mode. Unfortunately Alice's message length (in bytes) is not a multiple of 16. Suppose the last block of her message is just a single zero byte. How can she pad out the last block so that she can use CBC mode? Since this needs to be a reversible operation, how does Bob recognize the padding and remove it?

IN PYTHON   Given the following six-node wide area network for which the numbers attached to the links are a measure of the “delay” in using that link (e.g., some lines could be more heavily used than others and therefore have a longer wait time), answer the following question.   What is the shortest path from node A to node D, where shortest path is defined as the path with the smallest sum of the delays on each individual link? Explain exactly how you went about finding that path.