Teredo sunset - did it happen?

[Brian E Carpenter]

On 18/11/2014 07:12, Phil Mayers wrote:
> On 17/11/2014 17:43, Darren Pilgrim wrote:
> 
>>> Any ideas what's going on? Microsoft, anyone care to comment?
>>
>> Microsoft released an Windows Update for the prefix policy table.  The
>> update dropped Teredo's precedence to lower than IPv4.
> 
> Just to be clear - are you suggesting they did this instead of
> sunsetting Teredo altogether?
> 
> In any case, I was always under the impression this was the day-one
> experience - Teredo would only be used to talk to another Teredo DNS
> name or an IPv6-only name in the absence of native IPv6. Am I mistaken?

I think that was always the intention, but unmanaged tunnels are
liable to behave undesirably. From what Dave Thaler said during
the discussion at the IETF last week on deprecating 6to4, MS
clearly sees Teredo for Xbox-to-Xbox as operational and Teredo
for regular client/server use as undesirable, same as you do.
Dave therefore wanted no change to the RFC 6724 default policy
table, which I assume is exactly what Windows now ships.

Then, even if the Teredo interface comes up, since
::ffff:0:0/96 has higher precedence than 2001::/32, Teredo will
not be tried unless there is no IPv4 address at all for the
target host.

But if the client has the old RFC 3483 policy table,
::ffff:0:0/96 has the lowest precedence so Teredo would win over
IPv4, which is a Bad Thing. There isn't much to be done about
that unless the user has netsh skills.

    Brian