How to report IPv6 bug to Microsoft - Vista and 7 won't "undeprecate" a prefix
msmith at internode.com.au
Thu Apr 7 08:04:36 CEST 2011
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".
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
(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.)
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