Windows IPv6 network tweaks

Enable icmp echo-request in Windows IPv4 and IPv6
netsh advfirewall firewall add rule name="icmpv6 echo-request" dir=in action=allow protocol=icmpv6:128,any
netsh advfirewall firewall add rule name="icmpv4 echo-request" dir=in action=allow protocol=icmpv4:8,any
Windows by default generate random interface IDs for non-temporary autoconfigured IPv6 addresses

To change this type: 

netsh interface ipv6 set privacy state=disabled store=active
netsh interface ipv6 set privacy state=disabled store=persistent
netsh interface ipv6 set global randomizeidentifiers=disabled store=active
netsh interface ipv6 set global randomizeidentifiers=disabled store=persistent
Disable 6to4 and Teredo, by entering the following commands in an Administrator shell:
netsh interface teredo set state disabled
netsh interface ipv6 6to4 set state state=disabled undoonstop=disabled
netsh interface ipv6 isatap set state state=disabled

and/or disable IP helper service: 

net stop "IP Helper"

or use http://support.microsoft.com/kb/929852#fixit4me (link also includes - how do completely disable/enable IPv6)