Internet is growing, and it is growing fast—the number of connected hosts is doubling almost every year, while the volume of traffic is doubling every 6 to 10 months. This growth has been sustained for several years, and all measures indicate that it may well continue at the same rate for another five years, at least. Internet providers must invest continuously to build up network capacity, but they also have to cope with a side effect of the growth, the strains it places on the routing fabric. 10.1 Addresses, Networks, and Routing Tables Nobody knows exactly how large the Internet is, how many Internet users there are worldwide. The very high growth rate that it has enjoyed makes all measurement attempts approximate at best, since the numbers may well change during the measure. In my opinion, one of the most significant measures is the number of hosts registered in the domain name system. This number is not directly related to the number of users: for example, there are 18 million AOL users, but AOL declares fewer than 2 million addresses. However, the size of the address space is a good indication of the size of the routing problem, because the routing system must guarantee that all the registered addresses will be reachable. (The numbers between 1991 and July 1996 come from the DNS studies conducted by Network Wizards; those between September 1996 an
To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.