Limits of Current IP Addressing

The current IPv4 address scheme is based on 32-bit numbering and limits the number of available IP addresses to about 4.1 billion. Many companies and organizations (particularly in the United States) were assigned very large blocks of IP addresses in the early stages of the growth of the Internet, which has left a shortage of "open" addresses. Even with careful allocation of Internet-connected host IP addresses and the use of network address translation (NAT) to provide communication to and from machines behind an Internet-connected computer, the Internet might run out of available addresses.

To solve this problem, a newer scheme named IPv6 (IP version 6) is being implemented. It uses a much larger addressing solution based on 128-bit addresses, with enough room to include much more information about a specific host or device, such as global positioning server (GPS) or serial numbering. Although the specific details about the entire contents of the an IPv6 address have yet to be finalized, all Internet-related organizations appear to agree that something must be done to provide more addresses. According to Vint Cerf, one of the primary developers of the TCP/IP protocol, "There will be nearly 2.5 billion devices on the Internet by 2006, and by 2010 half the world's population will have access to the Internet."

You can get a good overview of the differences between IPv4 and IPv6 policies regarding IP address assignments, and the registration process of obtaining IP addresses, by browsing to Read the Linux IPv6 HOWTO by browsing to

Ubuntu supports the use of IPv6 and includes a number of networking tools conforming to IPv6 addressing. Support for IPv6 can be configured by using settings and options in the file named network under the /etc/sysconfig directory, along with changes to related network configuration files, such as /etc/hosts. Many IPv6-based tools, such as ipcalc6, ping6, and traceroute6, are available for Ubuntu. See various files under the /usr/share/doc/initscripts directory for more information specific to setting up IPv6 addressing with Linux and Ubuntu.

Migration to IPv6 is slow in coming, however, because the majority of computer operating systems, software, hardware, firmware, and users are still in the IPv4 mindset. Supporting IPv6 will require rewrites to many networking utilities, portions of operating systems currently in use, and firmware in routing and firewall hardware.

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