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February 22, 2011

IPv6: An Intro

IPv6, for those unfamiliar, is the Internet Protocol version 6, the next evolution of network addressing and the internet. Just like Bill Gates’ famous statement about 640KB being all that we’d ever need in computing, so the designers of IPv4 (Internet Protocol version 4) thought of the 4.3 billion addresses in the 32 bits of IPv4. Surely that’s enough! Nearly one per every person on earth?!? But how many of us have a smart phone (iPhone, Android, BlackBerry, etc), a home computer, an Xbox or PS3…not to mention any internet-connected devices at your place of employment?

Those 4.3B quickly disappear, especially when a lot of blocks were eliminated from distribution from day 1 (10.x.x.x, 172.16.x.x-172.31.x.x, 192.168.x.x, and all the multicast and experimental chunks). Add to that the Class A’s (16 million address blocks) wastefully given to large corporations, and you can see where the addresses went. Two weeks ago, the last Class A and thus, the last allotment from the centralized addressing authority, IANA, was dispensed. In technical terms, IPv4 is officially spent. Sure, ISPs still have supplies, but those are now a non-replenishable  resource.

Enter IPv6. 128 bits of addressing glory. The IETF (Internet Engineering Task Force) decided that once was enough with regards to running out of space (at least until we expand to other worlds). How many addresses is that, you ask?

Approximately: 340,000,000,000,000,000,000,000,000,000,000,000,000
(I’ll let you name that number)

And quantity wasn’t the only change (by far!). An IPv4 address follows a decimal format that looks like: 192.168.100.254. Each of those “octets” (the three number between periods) can range from 0 to 255, so if you want to remember an address, at worst it varies between 0.0.0.0 and 255.255.255.255, essentially a very long phone number. IPv6 laughs at that…

fe80:24c5:9001:a34b:8000:6902:ccef:3553 could stare back at you, if you ask for your computer’s IPv6 address! “What the heck?!?! What are letters doing in an IP address???” That’s right. You’re looking at hexidecimal in IPv6, so every character ranges from “0” (zero) to “f”. Now, that example address is probably a worst-case scenario, but it could happen. The good news is that most schemes allow you to abbreviate at least a few of those segments by omitting leading zeroes and using double colons “::” to collapse segments composed entirely of zeroes. The fact remains, though, that the address range is now:

0000:0000:0000:0000:0000:0000:0000:0000 – ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff

The other features, blessings, and curses of IPv6 are far more numerous than this little intro is intended to cover, but that gives you a little taste of what’s coming. Of anecdotal value, I think the only thing shorter is your computer’s loopback address: “127.0.0.1” becomes “::1”.

In the next post, we’ll walk through the breakdown of those eight (8) address segments, subnetting, and maybe a few other things. Until then…

add:beef:2:a:cafe:4:bad:f00d

🙂

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By Chris Gurley, MCSE, CCNA
Last updated: February 22, 2011

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