teredo.ipv6.microsoft.com off?

Tim Chown tjc at ecs.soton.ac.uk
Fri Jul 19 12:15:01 CEST 2013

On 19 Jul 2013, at 10:34, Phil Mayers <p.mayers at imperial.ac.uk> wrote:

> On 07/18/2013 09:09 PM, Brian E Carpenter wrote:
>> Wait... I had the impression that iff there was no other IPv6 connectivity,
>> Teredo was used in older Windows because of the generic "prefer IPv6" rule.
>> The default RFC 3484 table covers 6to4 but not Teredo.
> AFAIK, every version of windows (i.e. Vista, 7, 8) that comes with Teredo also comes with a de-pref rule for it, not just "recent" versions.
> Put another way, Teredo should never be preferred over IPv4, because all versions of Windows with Teredo use extended RFC 3484 rules.
> Most of the Teredo activity we see is when IP addresses are used directly (i.e. no getaddrinfo). For example, BitTorrent connections where peers were looked up in DHT/PEX. In these cases, an IPv6 address will be connected to over Teredo if there's no other connectivity.

Again, my understanding is the same as Phil's here.

Many vendors/implementors started adding rules that ultimately appeared in RFC6724 long before RFC6724 was published.  It took 6 years(!) for that update to be completed through the IETF.   

There are however some platforms stuck on 3484 or that don't follow such rules (Mac OSX is an interesting one...)


More information about the ipv6-ops mailing list