Problem 18
Suppose you purchase a wireless router and connect it to your cable modem. Also suppose that your ISP dynamically assigns your connected device (that is, your wireless router) one IP address. Also suppose that you have five PCs at home that use \(802.11\) to wirelessly connect to your wireless router. How are IP addresses assigned to the five PCs? Does the wireless router use NAT Why or why not?
Problem 18
Use the whois service at the American Registry for Internet Numbers (http://www.arin.net/whois) to determine the IP address blocks for three universities. Can the whois services be used to determine with certainty the geographical location of a specific IP address? Use www.maxmind.com to determine the locations of the Web servers at each of these universities.
Problem 19
Consider sending a 2400-byte datagram into a link that has an MTU of 700 bytes. Suppose the original datagram is stamped with the identification number 422 . How many fragments are generated? What are the values in the various fields in the IP datagram(s) generated related to fragmentation?
Problem 19
Compare and contrast the IPv4 and the IPv6 header fields. Do they have any fields in common?
Problem 20
It has been said that when IPv6 tunnels through IPv4 routers, IPv6 treats the IPv4 tunnels as link-layer protocols. Do you agree with this statement? Why or why not?
Problem 20
Suppose datagrams are limited to 1,500 bytes (including header) between source Host A and destination Host B. Assuming a 20-byte IP header, how many datagrams would be required to send an MP3 consisting of 5 million bytes? Explain how you computed your answer.
Problem 21
It has been said that when IPv6 tunnels through IPv4 routers, IPv6 treats the IPv4 tunnels as link-layer protocols. Do you agree with this statement? Why or why not?
Problem 22
Suppose you are interested in detecting the number of hosts behind a NAT. You observe that the IP layer stamps an identification number sequentially on each IP packet. The identification number of the first IP packet generated by a host is a random number, and the identification numbers of the subsequent IP packets are sequentially assigned. Assume all IP packets generated by hosts behind the NAT are sent to the outside world. a. Based on this observation, and assuming you can sniff all packets sent by the NAT to the outside, can you outline a simple technique that detects the number of unique hosts behind a NAT? Justify your answer. b. If the identification numbers are not sequentially assigned but randomly assigned, would your technique work? Justify your answer.
Problem 22
Discuss how a hierarchical organization of the Internet has made it possible to scale to millions of users.
Problem 23
Is it necessary that every autonomous system use the same intra-AS routing algorithm? Why or why not?
