IPv6 Frequently asked questions. While somewhat specific to deployment plans at UW, some general issues are covered as well.
- Is IPv6 a replacement for IPv4?
No. IPv6 will be deployed alongside and parallel to IPv4. This is called "dual stack", meaning we will run both v4 and v6 at the same time.
This is not much different from when we ran IPv4, DECNET, Appletalk, and IPX all at the same time.
At some point, IPv4 might be limited to obscure or legacy environments after a number of years, similar to our slow migration away from Appletalk and IPX.
- What are the compelling reasons to switch to it now?
There is no reason to switch protocols, as v6 is not a short term replacement for v4. However, it makes sense to start deploying now in a controlled, cost-effective, and phased manner as opposed to scrambling at some point later.
- By what date will it be crucial that we are using IPv6?
There is no set date. However getting an early start will be a significant advantage. In addition, making IPv6 a requirement for new systems as part of normal procurement cycles now will ensure that we will have v6 capability in a cost-effective manner.
- What does IPv6 do that IPv4 can't do?
- You can put as many hosts on a subnet as you want.
- You can get contiguous, aggregatible address space that makes firewall
rules and other address based access control mechanisisms easy to maintain.
- Gives every internet connected host a unique address, eliminating the use of NAT.
- Can we install a box that would translate between v4 and v6?
This technology is very immature but slowly evolving. It could likely be slow, expensive, and prone to obscure application incompatibilities due to the nature of packet translating. At this point, it makes more sense to deploy v6 alongside v4 in dual-stack mode.
- I heard IPv4 is "running out". What does that mean?
The internet at large is running out of unique IPv4 address space due to continued large growth of connectivity such as mobile devices and growth into Asian countries.
Here on campus, we are also running out of IPv4 addresses. As existing networks such as ours continue to grow there will not be any more addresses available for use. This means that a lot of time and money will be spent on renumbering networks and deploying NAT.
- I heard that department X has a lot of ipv4 space, can't we just
get that back?
The rate of growth of the network has, in general, outstripped the rate at which we can reclaim or renumber networks. While there are some large opportunities for reclamation that will eventually come to fruition, this is still not a long-term nor sustainable course of action.
- Wouldn't it make more sense to wait and let someone else
go through the process first?
Since much of the IPv6 networking protocol stack has been around for years, it is relatively stable and mature in all but a few areas. Some campus department networks already have IPv6 deployed today and some in particular have been running IPv6 alongside v4 for over 5 years.
- How much will I have to understand the technical aspects of IPv6?
You will need to understand IPv6 at the same level as you understand IPv4. For example, if you manage DNS entries or firewall rules, you will need to know the appropriate syntax for v6. If you are an application developer, you may need to make sure you are using system calls appropriately.
- What is likely to break when I turn on IPv6?
IPv6 compatibility is mostly an application problem. Each application needs to know how to recognize, store, parse, etc IPv6 addresses in addition to IPv4 addresses. This is sort of like Y2k, where applications had to use a 4 digit date field instead of 2. Applications also need to know how to query DNS properly for both v4 and v6.
- Do my hosts support IPv6?
Most likely yes. For windows hosts Windows 7 or Vista has support turned on by default. In WinXP, you to explicitly enable it. In OS X it is enabled by default at least since 10.4. Nearly all Linux distributions have support and many enable it by default.
- How do I use a firewall with IPv6?
Most host-based firewalls included with the operating system have IPv6 and are enabled by default. The current campus network firewalls do not have IPv6 support, but the next generation of the service will.
- How do I ask questions or find out more?
To contact UW Network Engineering, open a case with the DoIT Helpdesk.