Most Internet traffic is carried by backbones of independent ISPs, including MCI, AT&T, Sprint, UUnet, BBN planet, ANS, and more. Currently the Internet Society, the group that controls the INTERNET, is trying to figure out new TCP/IP to be able to have billions of addresses, rather than the limited system of today. The problem that has arisen is that it is not known how both the old and the new addressing systems will be able to work at the same time during a transition period. (Author's Note: The content of this guide was compiled in 1997. Obviously much has happened since this time. Please seek other resources for newer advancements.)