● Coming up with an IPv6 addressing scheme is one of the most important of all your efforts. When else do you get a second chance to correct all the mistakes made with your IPv4 addressing plan? Rather than just doling out subnets sequentially, you should think through the implications and come up with a plan that will be flexible enough to take your enterprise into the foreseeable future and beyond. Perhaps you only have two or three sites, but what will your organization look like in 50 years? Perhaps now your organization is limited to one geographic territory, but who knows what will happen in 50 years? The point is, before you begin throwing IPv6 space at your network, come up with the overarching principles that will guide all your IPv6 assignments.
● Prior to acquiring IPv6 address space from a service provider, be sure you understand the differences between provider independent (PI) and provider assigned (PA) address space. This concept is fundamentally new in IPv6, so be sure you understand all the implications of which type you acquire.
● I recently read that nearly half of all organizations track IPv4 space manually. This is clearly unsustainable in IPv6. If you do not have an IPAM (IP address management) solution deployed, now is the time to find one. If you do have an IPAM, IPv6 readiness should have been assessed during the reconnaissance task described.
● Don't forget the WAN. You need to understand your options for connecting to the IPv6 Internet. Different service providers offer different options, so be sure to consider them all. Sadly, many service providers do not yet have IPv6 connections available for customers yet. In this case, you may want to consider finding another provider, or alternately using a tunnel broker.
● Don't overlook your tools. One of the weakest links right now in terms of vendor IPv6 support is in the category of tools. This includes network node management, packet capture and analysis, server management, SNMP management, IDS/IPS solutions, etc. Be sure to focus early in the game on enabling IPv6 on your tools wherever possible.
● Pay special attention to anything that is fundamentally different between IPv6 and IPv4. You may want to instruct your TA leads and contributors to make a list of these items as they learn more about IPv6. I already mentioned the PI vs. PA address space issue as one fundamental difference. A few others include: EUI-64 addressing, stateless auto configuration, ARP replaced by neighbor discovery, no more broadcast, no more fragmentation by intermediate devices, and all subnets are /64s. These are just a few of the things that make IPv6 different than IPv4.
● IPv6 support among vendors is not nearly as mature as IPv4. Because of this, there may be bumps along the road as IPv6 is rolled out, so be sure expectations are properly set.
● Don't forget the need to properly train your staff. This is especially critical for the operations folks who will be working with IPv6 on a day-to-day basis.
● Lather, rinse, repeat. Don't forget that the steps in this chapter and the previous are meant to be performed twice, once for each phase of the transition as described in Chapter 2.