I am trying to begin implementing IPv6 within our network to explore using Direct Access. I'd like to start with Unique Local addresses (FC00::/7), to perform internal routing only. We do not yet have our ISP or web filter IPv6 enabled.
When I enable IPv6 on the router within one of our VLANs, machines on that network have a noticible delay in Internet Explorer reaching sites that have a global IPv6 address (Google, Facebook, etc.). It will eventually fail over to IPv4 and the page is displayed, but it takes about 15-20 seconds. Chrome and Firefox on this machine recognize that the route is unavailable, and come up with the pages right away. We do not have any proxy settings enabled on the clients. These systems are Windows 7 SP1 running IE 9 and all the latest patches through WSUS.
If I ping Google from this subnet, the IPv6 address is resolved but the pings come back unreachable pretty quickly. If I use ping -4, the IPv4 address responds.
Is there a way to make IE recognize that the route is invalid (since it's using a unique local address) and revert to IPv4 quicker?
Thanks!
P.S. I did ask this on the IE forums first and was suggested to ask here: http://answers.microsoft.com/en-us/ie/forum/ie9-windows_7/internet-explorer-slow-with-ipv6-unique-local/1b87e047-391d-450f-be4b-562099e8f2e5