Note: This is part one of two; the second part will be posted next week.
No matter what your position in IT might be, you're probably pretty darn familiar with IPv4. You can't configure the first thing on a network today without at least having some basic idea how subnet masks, default gateways, and DNS allow the network to function. If you're tasked with day-to-day management of a larger network, you may be very familiar with a whole slew of deeper info, such as how to set up DHCP to autonumber workstations, perform more complex subnetting, and configure dynamic routing protocols.
For better or for worse, everything you've learned about IP throughout your career is about to change.
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The IANA issued its last /8 block of IPv4 addresses earlier this month. The Regional Internet Registries are on pace to run out of smaller blocks to assign to ISPs and corporations within a year or so. Many ISPs have done a good job planning ahead and have a lot of space on hand, but it can't last forever. It's not an issue of whether IPv4 address space exhaustion will force you to get on the IPv6 bandwagon, but when.
If you haven't yet, there's no time like the present to start getting your feet wet. Wrapping your mind around IPv6 now is the best defense against being caught flat-footed before it's inevitably crammed down your throat. One of the cheapest and most educational ways to do this is to build yourself a lab with free software and cheap discarded hardware.
Here's how I recently built an IPv6-capable router/firewall in a few hours with junk lying around my office.
What you'll need to get started
First off, you'll need a piece of hardware. Anything with a pair of network interfaces will do. In my case, I had an old P4 pizza box-style server with a single hard drive kicking around that fits the bill, but you can get by with just about anything that has 4GB of drive space and a pulse (a CD-ROM drive will make things easier, but isn't strictly necessary). For my purposes, I wanted something I could easily attach directly to a subscriber-grade Internet connection, so I didn't pursue using a VMware host, but that's also an option if you have one available to you.
Next, you'll need a good operating system. There are lots and lots of ways to do this. In my case, I chose to use Vyatta Core (the free, community supported version of Vyatta Enterprise). Vyatta is a commercially maintained Linux distribution (based on Debian Linux) that draws together a raft of different open source networking packages and unites them under a common management framework. One of the features that makes Vyatta a great choice for a lab/educational tool is its thorough support for IPv6 and a wide variety of routing protocols, including OSPF and BGP. To be sure, you can do everything that Vyatta does with pretty much any major Linux distribution, but Vyatta has already done a lot of the work for you.