CPSC 155b Spring 2003 E Commerce Doing Business on the Internet Homework 1 Page 1 of 6 Homework 1 This assignment is due in class on Tuesday January 28 It covers readings and lectures through Thursday January 23 Late homeworks will not be accepted Write your name your e mail address and the date on the paper that you hand in 1 MASS MARKET BUSINESSES AND NETWORK EFFECTS 10 points A 6 points Explain briefly the difference between a mass market business and a business that exhibits network effects B 4 points Give two examples of mass market businesses that were discussed in class one of which relies much more heavily on network effects than the other identify which of the two relies much more heavily on network effects 2 INTERNET ARCHITECTURE AND PROTOCOLS 10 points A 2 points What type of number must your browser translate the name www microsoft com into so that you can view a page on the Microsoft website B 4 points If the correct translation of www microsoft com is not already known to your browser which Internet service is used to look it up Briefly explain the lookup process C 4 points For one point each identify the Internet layer that is most closely associated with each of i Retransmission of dropped packets ii Congestion control iii Interdomain routing iv Ethernet connection 3 OSPF ROUTING 22 points Open Shortest Path First OSPF routing is used to determine best routes within a single administrative domain Because the routers involved are in the same domain they can work together towards a common simple goal which is choosing the lowest cost path available In addition because domains are relatively small compared to the Internet it is possible to share more information about the network without causing congestion Thus OSPF works by sending information about the network topology throughout the network so that each node can calculate the lowest cost path to reach a destination For example consider a node A that has two neighbors B 2 A 5 C A would then broadcast the following link state packet LSP Link A B A C Weight 2 5 CPSC 155b Spring 2003 E Commerce Doing Business on the Internet Homework 1 Page 2 of 6 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 a 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 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 three neighbors 1 B 2 A C 4 D CPSC 155b Spring 2003 E Commerce Doing Business on the Internet Homework 1 Page 3 of 6 and A receives the following LSPs Link B A B E Weight 2 2 Link C A C E Weight 1 3 Link D A Weight 4 Link E B E C Weight 2 3 A 4 points Give the forwarding table for A B 5 points Assume that a new node F joins the network A receives the following updated LSPs Link C A C E Weight 1 3 C F 1 Link D A D F Weight 4 1 Link E B E C Weight 2 3 E F 3 Link F C F D Weight 1 1 F E 3 Give the new forwarding table for A including the new entry for destination F C 13 points Assume that the link between A and C fails and must be withdrawn Assume further that the link between A and D becomes less congested and so both A and D recalculate the cost of the A D link to be 1 i Give the updated LSPs that A C and D send 3 points ii Give the updated forwarding table for C 5 points iii Give the updated forwarding table for D 5 points CPSC 155b Spring 2003 E Commerce Doing Business on the Internet Homework 1 Page 4 of 6 4 BUSINESS ON THE INTERNET 12 points In Trust and Risk in Internet Commerce Camp identifies the following stages of a commercial transaction account acquisition browsing or discovery price negotiation payment merchandise delivery dispute resolution and collection and final settlement For simplicity restrict your attention in this question to business to consumer transactions e g those on Amazon or consumer to consumer transactions e g those on eBay and ignore business to business transactions Choose three of these stages and for each state whether you think that the use of the Internet enables a unique type of consumer experience in that stage If you think that it does briefly explain what is unique about the consumer experience and what property of the Internet enables this unique experience If you think that it does not give another example of a communication system or environment in which a consumer can have a similar experience You will get 4 points for each correct answer 5 INFORMATION ECONOMY 12 points Recall that information goods often have high fixed costs and low marginal costs furthermore it is often the case that anyone i e not only the creator or authorized manufacturer can reproduce them Briefly describe three techniques that can be used to build effective information businesses despite this fundamental fact about information goods You will get 4 points for each correct answer 6 BGP ROUTING 34 points The Border Gateway Protocol BGP is used to determine best routes between sources and destinations that are not in the same autonomous system AS i e administrative domain Because paths often traverse networks managed by separate companies route choices are often determined by a combination of factors possibly including specific local preferences at each router business relationships with neighbors and path length BGP accommodates these complex routing policies that are not uniform throughout the Internet Because BGP performs interdomain routing i e between domains it is primarily concerned with reaching an AS containing a specific host destination not with reaching the host itself Once the packets are routed to the AS containing the destination the job of getting them to the specific host is left to intradomain routing i e within a domain For example to reach the host 192 1 12 14 from some faraway AS it is enough to know that 1 this host is contained within some AS say 1702 and 2 the faraway AS has a …