Every packet of data sent over the Internet is sent from one IP address to another. The IP addresses in the Internet serve somewhat the same function as phone numbers in the US phone system, fixed length numeric identifiers where the first part tells what network the address is on. Since the dawn of the Internet in the early 1980s, the IP addresses in use have been IPv4, 32 bit addresses which means there are about 4 billion of them. Unless you’ve been living under a rock, you’ve doubtless seen reports that the supply of IPv4 addresses is running out. Earlier this month IANA, the master allocation authority, handed out the last so-called /8, a large chunk of 16 million addresses, to one of the regional address registries, and sometime months or perhaps a few years after that, the registries will hand out the last pieces of their chunks. Then what?

The conventional wisdom is that everyone needs to support IPv6, a mostly compatible upgrade to IPv4 with much larger addresses, by the time the v4 space runs out. But I’m not so sure, particularly for e-mail.

There’s two unanswered questions here. One is is how hard it will be for new or expanding networks to get IPv4 address space. The other is how important IPv6 addresses will be to be able to reach the rest of the net. The conventional answers are very hard and very important, but I think the real answers to both, for the next several years, at least, is not very. Below is my three-part post where I opine about getting IPv4 address space, addressing and reachability.

A politically incorrect guide to IPv6, Part I

A politically incorrect guide to IPv6, Part II

A politically incorrect guide to IPv6, Part III

Written by John Levine, Author, Consultant & Speaker