How to report IPv6 bug to Microsoft - Vista and 7 won't "undeprecate" a prefix

[Ole Troan]

Mark,

> A number of our customers are having trouble with IPv6 under Windows Vista and 7 on our IPv6 trial.
> 
> Currently we are giving customers a static delegated prefix via DHCPv6-PD (a /60 currently). When they have an ADSL drop out, some IPv6 CPE is deprecating the assigned LAN interface global /64 prefix by sending an RA with a zero second preferred lifetime for the prefix. Windows Vista and 7 are quite correctly labelling the prefix as deprecated, as it still has a non-zero valid lifetime. Deprecating the prefix at this time makes sense as there is a possibility that the delegated prefix may not be re-assigned to the CPE after the ADSL link is restored, and may be re-assigned by the ISP to another customer. This is also the behavior specified in the recently published RFC6204, "Basic Requirements for IPv6 Customer Edge Routers".

no, it isn't.
this behaviour breaks local communication within the home.

> When the ADSL link comes up again, and the CPE re-acquires the same delegated prefix, it re-announces the same /64 onto the LAN with a non-zero preferred lifetime. Windows Vista and 7 receive and update the non-zero prefix lifetimes for the addresses, but do not change the addresses back to preferred. Windows XP does, as do other operating systems. Windows Vista and 7 not setting the addresses back to preferred seems to then cause IPv6 connectivity to then fail, causing Vista and 7 to revert back to using IPv4 only. Windows Vista and 7 have no trouble at this time with new prefixes, so the issue seems to be specifically related to changing a previously deprecated prefix back to a preferred one.
> 
> Does anybody know how I can report this bug with Microsoft on behalf of our customers?
> 
> (If anybody wants to have a go reproducing this, the latest CVS version of radvd now has a "DeprecatePrefix" option for prefixes. To view the IPv6 address status and lifetimes under Windows, use the "netsh interface ipv6 show address" "cmd" command.)

cheers,
Ole