IPv6 Is Coming. Time To Get Prepared
Posted by
Mike Fratto
August 24, 2011
IPv6 is coming. Sooner or later, you will be deploying IPv6 on your network, data center, or co-lo servers. It may be a few years off--longer if your ISP has a well thought out transition strategy in place--but IPv6 is different enough that you can learn the ins and outs on a smaller network before you have to deploy it widely. The question is where to start. Being IT nerds ourselves, we have put together an IPv6 resource page that contains articles and resources that we find useful in learning and experimenting with IPv6. If you are looking for resources, start there. If you have a good resource you want to share, send me an email and I will check it out.
Truth be told? If you understand IPv4, you will understand IPv6. The basics are similar enough that you will have a good foundation. Addresses have network and host components and routes are distributed much like IPv4 routes are distributed. The address space is bigger, but once you understand the addressing, it's pretty simple to read an address and know it's scope and purpose. Basic functionality works today but if you have never designed or managed an IPv6 network, you will have some studying to do. Get yourself a tunnel broker account for home. Get a router that forwards tunneled IPv6, and get busy.
The biggest changes are understanding the differences IPv6 addressing from IPv4 is how addresses are used and configured. IPv6 has the concept address types such as global addresses that can be routed, link-local addresses which are confined to a single broadcast domain, and site-local addresses which are confined to a single site. The latter two will be routed beyond their confines and they do have their uses. Using site local addresses means you can address hosts that should never be accessible beyond your borders--things like printers, VoIP phones, infrastructure, etc. Link and site local addresses give you a new tool to separate traffic other than VLAN's and firewalls.
How hosts are addressed is another area where IPv6 differs greatly from IPv4. Yes, you can allocate addresses using DHCPv6 like you do with IPv4 and some IT administrators plan on doing exactly that so they can more effectively manage their IP address space. Others will use StateLess Address Auto Config (SLAAC) which combines a host's MAC address and the site's network address to forma globally unique address. SLAAC is great for ease of use but hampers host discovery and IP address management (IPAM) since you never know when a new host hits the network and scanning an IPv6 subnet will take years.
Of course there are going to be transition technologies that you will require from your ISP or co-lo vendors to get your services and your users to and from both IPv4 and IPv6 networks, but also transition technologies you will have to deploy inside your network to support legacy IPv4 gear that won't support IPv6. If you are an old and crusty IT admin like Howard Marks or you know an old and crusty IT admin, ask them how long they ran dual-stack IP/IPX (an alternative layer 3 protocol to IP) gateways, servers, and hosts.
The sooner you start, the better off you will be when your IT manager asks you to turn on IPv6.
Mike Fratto is editor of Network Computing. You can email him, follow him on Twitter, or join the Network Computing group on LinkedIN. He's not as grumpy as he seems.
