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...)
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