Greater Lafayette Information Technology Society

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by Wally Hubbard, Avosot

IPv6: February 201

Jeff Schwab
Purdue ITaP

Jeff Schwab

The organizations that allot Internet addresses are close to running out of new IPv4 (Internet protocol version 4) addresses to hand out. The last blocks went to the regional assignment authorities in early February, and could run out in a matter of months in the fast-growing Asian region. U.S. addresses are still in relatively good supply. Jeff Schwab, of Information Technology at Purdue (ITap), told the crowd at GLITS, "don't panic." The switch from the old system, IPv4, to the new, IPv6, won't be complete before everyone in the room has retired. However, at some point, both the old and new systems will be in use, and that means twice the work when it comes to setting up networking.

IPv4 numbers look like, while IPv6 addresses look like 1050:0000:0000:0000:0005:0600:300c:326b. IPv4 addresses are usually written with decimal digits. IPv6 uses hex digits. IPv4 addresses use 32 bits, IPv6 addresses use 128. There's a notation that eliminates the need for a string of zeroes in IPv6 addresses. The example address above can also be written as 1050::5:0600:300c:326b, although that's still a lot of typing. The double-colon is replaced with the appropriate number of zeroes, and can be used only once per address.

Purdue and other Indiana educational instutions already have blocks of IPv6 addresses assigned. Right now, the barrier to obtaining a block of addresses is low.


Schwab advised against buying any network devices that do not support IPv6, but said not to worry about printers, unless they need to be accessible from the Internet! Microsoft OS's (operating systems) newer than XP, and newer Linux and Apple OS's support IPv6, although Apple does not support DHCPv6 automatic address assignment. Normally a computer's MAC address (Media Access Control/the 48-bit address burned into network interface hardware) is used as part of the IPv6 address, but Windows scrambles the MAC portion of the IPv6 address on every boot—a privacy feature that can be turned off if it causes problems in getting through a firewall.

One of the major problems will be moving data between IPv4 and IPv6 addresses. Although an IPv4 address can be encoded as IPv6, there's no way to encode IPv6 within IPv4. A frequent solution will involve NAT (network address translation) hardware units.

Since Purdue has a large number of international students, and IPv6 is likely to take off first in Asia, Purdue will face the challenge of supporting IPv6 early so that its many international students can enroll, and communicate with their parents and friends, using their IPv6 devices.

Jeff's PowerPoint has more information in it, and is available in .pptx and .pdf files, or with graphics removed, in this text file.