Low End Mac's Online Tech Journal

IPv6: The Next Generation Internet

Dan Knight - September 1998

The internet has been around since 1969, when Arpanet connected four computers. By 1977, that number had reached 100.

The term internet was coined in 1983, the year TCP/IP became the standard internet protocol. The following year there were over 1,000 hosts on the internet.

Then came the explosion: 10,000 hosts in 1987, 100,000 hosts in 1989, one million hosts in 1992, and 10 million hosts in 1996. Since 1984 the internet has been growing almost tenfold every three years.

But we're heading straight for a problem: the current protocol, IPv4, uses 32-bit addresses, limiting the internet to 4 billion devices (computers, printers, or anything else with an IP address). At the current rate of growth, which shows no sign of stopping, those 4 billion addresses will be completely exhausted by 2004.

Unless the exponential growth of computerization and the internet is slowed or halted, IPv4 needs to be replaced soon.

IPv6

At the same time the internet is reinventing itself to handle the explosive growth of data, it is planning a transition to IPv6, which offers more than just additional addresses.

The most crucial reason for creating a new standard is the limited number of IP addresses available under IPv4. Early talk was of a 6-byte (48-bit) address, which would provide 65,000 times as many addresses.

But the group creating the IPv6 standard decided to go well beyond that. Realizing that internet-connected devices will soon be ubiquitous, and that they will easily outnumber the population, the new protocol uses 128-bit addresses. This goes well beyond billions, trillions, or quadrillions. My calculator can't display the full number, but it rounds off to 3.4 x 1038.

If humanity developed warp drive and populated the heavens, and if at the same time our internet use grew tenfold every three years, it would take a century to use every possible address.

In brief: that's essentially a limitless supply of IP addresses

There are other benefits to the IPv6 addressing range. Under IPv4, the IP number of a device says nothing about its physical location or where it is connected to the internet. This means data sent from 123.45.67.89 to 98.76.54.32 doesn't know how to reach its destination. Instead, routers use huge lookup tables to determine where these bytes must go.

Under IPv6 addresses will be assigned according to geography and network topology. The first byte might localize the address to a planet or continent. The next could narrow that down to a specific nation. The third might work on a state and provincial level. A fourth could identify the ISP responsible for assigning the remaining 12 digits of the IP address within that region.

That's just a possible scenario. Maybe they'll want to reserve two bytes for planets, or even three. With so many potential addresses, better to plan ahead. Even if we never colonize space, the remaining 104 bits provide more addresses than we could ever use on Earth.

IPv6 could mean the end of dynamic IP addresses. With so many numbers available, every device could be assigned a fixed IP address among the thousands or millions available through your ISP or business. This would also immediately identify a portable computer on the road, easing access to your home server for email.

What else does it do?

IPv6 also changes packet headers, making them much more useful. IPv4 headers are variable in length, meaning the packet header has to tell the system how big it is. Under IPv6, that is replaced with a fixed-length 24-byte header. Not only will it be more efficient for hardware to handle fixed-length headers, this also provides plenty of room for traditional header data plus the 128-bit sending and receiving addresses.

One part of the new header is a flow label, which will be used to identify real-time streaming data (audio, video, etc.) and prioritize handling based on the type of data being sent.

If a single 24-byte header isn't enough, IPv6 permits chaining headers together as needed, making the protocol readily extensible when unanticipated technologies make it necessary.

That's planning ahead!

When can I get it?

The big question is deployment. There will be a time of transition during which the internet will simultaneously be handling IPv4 and IPv6 data (IPv6 accommodates that by tunneling IPv4 packets). According to InfoWorld (24 August 1998, p. 62), the internet is expected to be 100% IPv6 compliant by 2010.

IPv6 is being tested. InfoWorld urges IS departments to begin learning IPv6 as soon as possible.

But to my knowledge, there is no Macintosh support for IPv6 yet. I hope it will be part of Mac OS X.

I also hope Apple or someone else will release whatever supporting software is necessary for the legions of older Macs out there to use IPv6 instead of being consigned to the scrap heap. This would mean an update to MacTCP for the older Macs that don't support Open Transport, as well as an updated TCP/IP to allow use of IPv6 on Macs that can run Open Transport but won't be able to use OS X.

Maybe it's a bit much asking Apple to offer that level of support for older hardware, but they're the company that had the wisdom to design computers without a Y2K bug in the first place - and the common sense to build reliable computers that last and last.

Apple, I hope you're listening. Nice as it will be to have a G4 computer with OS X and IPv6 at some point, I'd also like to take my SE, Centris 610, and the rest of my collection into that future.

And I'm sure I'm not alone.

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