Alastair Johnson wrote:
Perry Lorier wrote:
Windows (an arguable large proportion of the hosts on the Internet) hasn't had IPv6 enabled by default until the release of Vista. Before then it's required obscure cli commands to activate. There doesn't appear to have been much point in doing v6 if a large chunk of your customers couldn't use it. Now they can.
Ah, but now the reverse problem occurs: There's little to absolutely no v6 content.
Who's going to want to publish their content on v6, when for the 99.9% of Vista v6 enabled PCs are going to have to reach it via 6to4 or Teredo, over Anycast through Timbuktu? Users are now complaining that your site is slow, and your traffic drops, your revenue goes away, and your v6 experiment fails.
So one thing that Windows does[1], which I thought was extremely clever is look where replies come from and investigate (via a ping) to see if it can use the gateway in the reverse direction. eg: hostA sends a message to hostB via the 192.88.99.1 anycast gateway (GwA). hostB replies to hostA via a gateway local to hostB (GwB). hostA receives the v6 packet, with the v4 source address of GwB, and remembers GwB's address. hostA then "validates" GwB's address by sending itself an ICMPv6 ping via GwB. if HostA receives a reply then it will consider using GwB to talk to HostB as it presumably has a much more direct path. So the practical upshot of this is that if you put a 6to4/Teredo gateway in your datacenter,, even if you don't publically announce them into the global routing table, then 6to4/teredo routes from your servers will follow the same routes as v4. Presumably internal addressing works just as well for them. --- [1]: I'm not 100% sure of this, but I'm fairly this is true. Some of the details may be slightly incorrect.