Comcast's 6to4 Relays

TJ trejrco at
Thu Apr 21 00:57:23 UTC 2011

On Wed, Apr 20, 2011 at 16:09, Doug Barton <dougb at> wrote:

> On 04/20/2011 12:50, Owen DeLong wrote:
>> Turnning off the servers will not reduce the brokenness of 6to4, it will
>> increase it.
> Depends on your definitions of "increase" and "broken." If all the relays
> disappeared tomorrow then the failure rate would be 100%, sure. But that
> would mean a single, (more or less) instant, deterministic failure that any
> modern OS ought to be able to handle intelligently; rather than the myriad
> of ways that 6to4 can half-succeed now. To me, that's a win.

While I can appreciate that 6to4 is far from perfect, and can create broken
situations - I will also admit to using 6to4 on more than an occasional
basis ... whether that be because:

   - my aircard gets a public IPv4 address, and thus 6to4 spins up
   - my Linksys CPE, out of the box, does 6to4 (SLAAC-advertising a prefix)
   - thus all of my home PCs do it as well (Win*, Ubuntu, etc.)

I find 6to4 to be far superior to no IPv6 connectivity, far easier than
launching a TSP client (which I also have, just in case) ... and, in fact,
to largely "just work" for all of my machines.  More relays will do nothing
but make this better, and as native IPv6 becomes  available I will happily
(and automatically!) move to that instead.

/TJ ... also a happy Comcast 6RD-beta user right now, so technically I am
not using 6to4 at home *right now* (but will be using 6to4 again after June
30th, when the 6RD trial ends).

More information about the NANOG mailing list