European IP addressing group: it’s time to jump on the IPv6 bandwagon

In May, ARIN, the organization giving out IP address in North America, told us it's time to start adopting IPv6.
Five months and another 76 million IPv4 addresses later, ARIN's
European counterpart, Réseaux IP Européens (RIPE) adopted a resolution
in much the same vein during its fall meeting last week. HangZhou Night Net

The RIPE Network Coordination Centre (NCC) is responsible for the actual distribution of IP addresses, while RIPE is the community part of the RIPE NCC. Unlike ARIN, RIPE doesn't have a board of trustees; instead, decisions are arrived at by consensus. (And after all of the consensus-building at RIPE meetings, there's time for some fun with a takeoff of a Don McLean classic, predictably called "The Day the Routers Died".)

RIPE believes that it's time to ditch IPv4 in favor of IPv6. "Growth and innovation on the Internet depends on the continued availability of IP address space," notes the resolution. "The remaining pool of unallocated IPv4 address space is likely to be fully allocated within two to four years. IPv6 provides the necessary address space for future growth."

Vacant lots in the class E space

As the number of available IPv4 addresses has decreased, there has been a furious debate in IP addressing circles about the class E address space. When IPv4 was first created, a block of address space was set aside for "future use." Some of that address space remains unused to this day. That's the class E space, which consists of all IPv4 addresses starting with the numbers 240 to 255. There are currently about 1.15 billion addresses still unused; adding the class E block would increase this to 1.42 billion and give us another year or so until we're out of IPv4 addresses. One problem: it turns out that operating systems, routers, and firewalls often reject addresses from the class E range as invalid. Windows and Cisco routers are very strict about this. Other systems (such as Mac OS X and FreeBSD) tend to accept the addresses in certain places, but then fail to properly use them.

The IPv4 address space as of early 2007

Although nobody is currently suggesting putting class E space into regular use, some people see some possible uses for these addresses. One example would be utilizing them in corporate networks that are so big that the network isn't big enough. Another would be for routers, which must talk to each other, but don't need to communicate with every possible PC connected to the Internet.

Opponents of opening up the class E address block (and proponents of IPv6) point out that even though it's much more work to add IPv6 to a network stack than removing a handful lines of code that block the 240 and higher addresses, upgrading all the necessary hardware will be a gigantic headache. As such, it's unlikely there will ever be a time when class E addresses are usable on the Internet at large. Even in private networks, it could be prohibitively difficult to update every last device that has a TCP/IP stack in it. It seems that when you paint yourself into a corner, the color you use doesn't really matter.