C consider two hosts a and b connected by a single


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Unformatted text preview: and flow control, but not congestion control). How would an application get this different service in today’s Internet? Answer: The application would use UDP sockets and implement the desired additional functionality (e.g., reliability and flow control) in the application itself. b. Explain why you can actually use the telnet protocol to perform a simple communication with a web server? Answer: Telnet is a text- based communication protocol, likewise is HTTP. If a client composes a text message that is HTTP standard compliant the server sends back the expected reply, which is shown in text (including the HTML content at the client. c. Consider two hosts, A and B, connected by a single link of rate R bps. Suppose that the two hosts are separated by m meters, and suppose the propagation speed along the link is s meters/sec. Host A is to send a packet of size L bits to Host B. Determine the transmission time of the packet, dtrans, in terms of L and R. Answer: d trans = L / R seconds. d. Suppose that Alice wants to send an email message to Bob. This will involve four entities: Alice’s mail client (for email composition and sending), Alice’s outgoing mail server, Bob’s incoming mail server, and Bob’s mail client (for email retrieval and viewing). Between which of these four entities does the SMTP protocol operate? What about the IMAP protocol? Answer: SMTP runs between Alices mail client and her server, and also (separately) between her server and Bob’s server. IMAP runs between Bob’s server and his mail client to retrieve messages from Bob’s...
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