CPSC 155a Fall 2001 E Commerce Doing Business on the Internet Homework 1 Page 1 of 6 Homework 1 This assignment is due in class on Tuesday September 25 It covers readings and lectures through Thursday September 20 Late homeworks will not be accepted Write your name your e mail address and the date on the paper that you hand in 1 INTERNET ARCHITECTURE 30 points For 5 points each match each item in the left hand column with the item in the right hand column with which it is most closely associated Browsers UDP Flexibility and empowerment IP layer Packet routing Increased core network functionality Reliable byte streams Application layer Low prices and ease of use End to end arguments Nonreliable byte streams TCP 2 INFORMATION ECONOMY 20 points a 5 points The basic technology for fax machines was patented in 1843 but fax machines remained rare until the mid 1980 s During the period from 1982 to 1987 fax usage experienced explosive growth because of positive feedback As the number of fax owners increased the usefulness of a fax machine grew the more useful fax machines were the more people bought them What well known property of communication technologies does this illustrate b 5 points True or false The vendor of a product that exhibits the phenomenon described in 2 a can definitely maintain a large market share once adoption reaches critical mass the product is so useful that customers cannot bear the switching costs of abandoning it even for something better c 5 points Production of an information good exhibits high fixed costs and low marginal costs Because creators of information goods can reproduce them cheaply potential competitors can copy or imitate them cheaply Nonetheless some information businesses are long lived and profitable Give an example of a technique that allows information producers to succeed in spite of this inherent property of information goods d 5 points Cable TV subscription packages Microsoft Office and a discounted subscription to the online Wall Street Journal for subscribers to the printed version are all examples of a common strategy for pricing information goods that we discussed in class What is the name of this strategy CPSC 155a Fall 2001 E Commerce Doing Business on the Internet Homework 1 Page 2 of 6 3 DIGITAL CONTENT DISTRIBUTION 20 points a 5 points What do the following businesses have in common Traditional broadcast television Training and support services for free software Certain pairs of complementary software products e g Adobe Acrobat Reader and the Adobe document preparation software b 5 points Technical protection measures 1 Can help rights holders prevent unauthorized copying 2 Can help verify legitimate provenance of digital documents 3 Will probably be more effective against professional content pirates when implemented in specialpurpose hardware for single purpose devices than they are when implemented in software for general purpose networked PCs 4 All of the above c 5 points In the physical realm the question of access to copyrighted works is cleanly separable from the question of reproduction of such works For example a single copy of a book can be read a single copy of a music CD played or a painting viewed by many people without any additional copies being made By contrast in the digital realm access usually entails reproduction For example software programs are copied from disk into RAM random access memory so that they can be run and Web pages are copied from remote machines onto local machines so that they can be viewed This fundamental difference between physically embodied copyrighted works and digitally embodied copyrighted works calls into question the continued applicability of one of the central elements of existing copyright law listed below Which one 1 2 3 4 The long duration of copyright ownership e g the fact that copyrights last much longer than patents The copyright owner s exclusive right to reproduce the copyrighted work in copies or phonorecords number 1 of Section 106 of U S Copyright Law The copyright owner s exclusive right to prepare derivative works based upon the copyrighted work number 2 of Section 106 of U S Copyright Law Fair use limitations on exclusive rights of copyright owners Section 107 of U S Copyright Law d 5 points The widely held belief that virtually all non commercial private use copying is lawful is wrong However in the physical realm copyright owners do not suffer much from non commercial private use copying because it does not destroy their markets and because its private nature usually means that it is limited in scope Is this true in the digital realm Answer yes or no 4 ROUTING 30 points I OSPF Routing Recall that in OSPF routing each node broadcasts the state of links physically connected to it and nodes use this information to calculate shortest paths and forwarding tables For example consider a node A that has two neighbors 2 A B 5 C CPSC 155a Fall 2001 E Commerce Doing Business on the Internet Homework 1 Page 3 of 6 A would then broadcast the following link state packet LSP Link A B A C Weight 2 5 Suppose A receives the following LSPs from other nodes Link B A B C Weight 2 1 B D 3 Link C A C B Weight 5 1 C D 4 Link D B D C Weight 3 4 From this information we can deduce the topology of the network calculate the shortest paths to the other nodes and construct the forwarding table Here is what the whole network looks like based on the above B 2 3 1 A D 5 4 C The shortest paths paths of minimum total weight from A to the other nodes are Destination A B A C Path A B A B C Total Cost 2 3 A D A B D 5 Then the forwarding table for A which indicates where next to send packets for a given destination is Destination B C Next Hop B B D B CPSC 155a Fall 2001 E Commerce Doing Business on the Internet Homework 1 Page 4 of 6 When A receives updated LSPs from new or existing nodes on the network it recalculates its forwarding table to reflect the new shortest paths Now consider a new network in which node A has two neighbors B 4 A 8 C and A receives the following LSPs Link B A B D Weight 4 11 Link C A C D Weight 8 5 Link D B D C Weight 11 5 a 5 points Give the forwarding table for A b 6 points Suppose a new node on the network E powers up and A receives the following new and updated LSPs Link B A B D Weight 4 11 B E 1 Link D B D C Weight 11 5 D E 3 Link E B E D Weight 1 3 Give the new forwarding table for A including the new entry for destination E CPSC 155a Fall 2001 E Commerce Doing Business