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Unformatted text preview: Chapter 1 Computer Network Foundation – IP Addresses In the mid-1990’s, the Internet is a dramatically different network than when it was first established in the early 1980’s. Today, the Internet has entered the public consciousness as the world’s largest public data network, doubling in size every nine months. This is reﬂected in the tremendous popularity of the World Wide Web (WWW), the opportunities that businesses see in reaching customers from virtual storefronts, and the emergence of new types and methods of doing business. It is clear that expanding business and social awareness will continue to increase public demand for access to resources on the Internet. There is a direct relationship between the value of the Internet and the number of sites connected to the Internet. As the Internet grows, the value of each site’s connection to the Internet increases because it provides the organization with access to an ever expanding user/customer population. 1.1 Internet Scaling Problems Over the past few years, the Internet has experienced two major scaling issues as it has struggled to provide continuous and uninterrupted growth: • The eventual exhaustion of the IPv4 address space. • The ability to route traﬃc between the ever increasing number of networks that comprise the Internet. The first problem is concerned with the eventual depletion of the IP address space. The current version of IP, IP version 4 (IPv4), defines a 32-bit address which means 1 2 CSE468/598 Lecture Notes that there are only 2 32 (4,294,967,296) IPv4 addresses available. This might seem like a large number of addresses, but as new markets open and a significant portion of the world’s population becomes candidates for IP addresses, the finite number of IP addresses will eventually be exhausted. The address shortage problem is aggravated by the fact that portions of the IP address space have not been eﬃciently allocated. Also, the traditional model of classful addressing does not allow the address space to be used to its maximum potential. The Address Lifetime Expectancy (ALE) Working Group of the IETF has expressed concerns that if the current address allocation policies are not modified, the Internet will experience a near to medium term exhaustion of its unallocated address pool. If the Internet’s address supply problem is not solved, new users may be unable to connect to the global Internet! Figure 1.1: Assigned and Allocated Network Numbers. The second problem is caused by the rapid growth in the size of the Internet routing tables. Internet backbone routers are required to maintain complete routing information for the Internet. Over recent years, routing tables have experienced exponential growth as increasing numbers of organizations connect to the Internet- in December 1990 there were 2,190 routes, in December 1992 there were 8,500 routes, and in December 1995 there were 30,000+ routes....
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This note was uploaded on 10/28/2009 for the course CSE 598 taught by Professor Huang during the Fall '09 term at Arizona.
- Fall '09