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Accelerating IPv6 Adoption With Proxy Servers
jgarzik writes "IPv6 presents a catch-22: the most popular web sites on the Internet
don't have any incentive to switch to IPv6 until a large portion
of their userbase is on IPv6, and their user base does not have a
large incentive to switch to IPv6 until many of the popular Internet
destinations support IPv6. My proposed solution is simple: Configure a proxy server that
serves IPv6 requests, passing those requests through
to underlying IPv4-only servers that not have yet been transitioned
to IPv6.
This article describes how to configure Apache's proxy server to fill this role, and suggests a few ideas for use."
> Do you use NAT (a home router)?
> Blame your IPv4-based ISP for not having enough
> address space for you.
For most peopel NAT actually solves a problem instead of being one.
Yeah, for some people it would be nice to be able to have their toaster online and reachable through the internet as well, and lack of addresses can make that difficult, but most people do not have a big urge to do such things.
They do however have a problem with their computer and an unfiltered internet connection.
A router that does NAT happens to function as a pretty good ip filter with state-keeping that is extremely easy to configure.
> Do you run a web-hosting company?
> You probably know how expensive address space
> is.
Yep, sadly enough, IPv6 sounds more advanced, and thus will be more expensive. The people who market the stuff have absolute controll over the supply so can set a price as they like.
The intention with IPv6 is that you won't have "unroutable" networks, like we do with private nets such as 10.x.x.x and 192.168.x.x. Everything will have a globally unique IPv6 address. There was in the original spec what were called a "site-local" addresses, which were private addresses not routed to the outside much like their IPv4 analogues, but those have been deprecated.
However, you'll have plenty of addresses because, in the current incarnation, you're not allocated a single address, but rather you are allocated a subnetwork, which is currently 2^64 addresses. So the first 64 bits are assigned to you by your ISP, and then the second 64 bits are yours to do with as you like.
So that addresses the question of NAT: there won't be any lack of IP addresses necessitating its use. I am only addressing the use of NAT as a way around limited address space, and not any of the other uses for which NAT has.
But what about DHCP? IPv6 comes with something more elementary, called "stateless autoconfiguration." Basically, the router constantly broadcasts your "prefix" to the subnetwork, which is the first 64 bit half of your 128 bit address your ISP assigns you. The machine then takes its subnetwork ID (the MAC address), and sets the second 64 bits to a function of that. In the case of Ethernet, it isn't the 48-bit Ethernet MAC address verbatim, but a published function of it. It's called stateless because it's always a function of whatever the network's prefix is plus some kind of subnet ID, and there's no concept of leases, or any of the state a DHCP server maintains.
There is not yet an equivalent mechanism for "stateful autoconfiguration," which is more what DHCP is, where you can automatically assign an arbitrary address to a client. You can of course statically configure an interface to have a specific address, but there is no automated mechanism to always assign a particular autoconfigured client a particular address you designate. There are proposed standards for an IPv6 version of DHCP, however, and I expect eventually such a beast will eventually come around.
Okay, I won't argue with you there.
It's deliberate overkill. It allows things like 64-bit subnets, which in turn allow for stateful autoconfiguration. It also allows for large chunks of address space that won't be allocated at all; if it turns out in the future that our current allocation method is inadequate for our needs, we can simply devise a new allocation method in this empty space, rather than having to migrate to a whole new version of IP.
Yes, if an IPv6 router had to hold nearly 150,000 routes in memory like it does in the current IPv4 world, it would be massive. Fortunately, IPv6 is designed to have properly aggregated addresses, so that things are much more hierarchical, and routing tables can be stored much more efficiently.
Aside from the fact that more and more connections are using much larger MTUs these days, IPv6 also supports more aggressive header compression than IPv4 did, often resulting in similarly compact headers.
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