On Jul 27, 2011, at 9:07 AM, John Mann (ITS) wrote:
Actually, I think one could argue pretty effectively that 6rd is 6to4-bis.
only if you're confused about the use cases for each.
In my opinion:
6to4 use case
- D.I.Y setup - no ISP involvement
- depend upon kindness of strangers to run the anycast relays
- some users have hard-to-solve reliability problems
- experimental / historic / not-recommended - should be off by default
- for users who would prefer "unreliable IPv6" to "no IPv6"
close, but no cigar.
the use case for 6to4 is when
- you have a public IPv4 address
- your ISP doesn't support any kind of IPv6 access
- there's no good native v6 tunnel endpoint near your host, or your host is
mobile
- you have applications for IPv6 other than to access content that is also
available via IPv4, OR your hosts are set up to prefer native IPv4 over 6to4
addresses
6rd use case
- configuration parameters set by ISP
- ISP runs the relays
- apparently production quality (see free.fr)
- for users who would prefer "no IPv6" to "unreliable Internet"
I agree that 6rd is not a replacement protocol for the 6to4 use case.
I will argue that the "6rd use case" is a replacement for the "6to4 use case".
If you have 6rd or any kind of native IPv6 available to you, you'll almost
certainly prefer it to 6to4, except perhaps when needing to communicate with
other hosts using 6to4.
The problem is that native IPv6 is not widely available, and will not be
universally available for maybe 10 years.
(Or maybe, never, because the deployment model in many people's minds assumes
that the only reason to use IPv6 is to "access content" that will continue to
be available via IPv4 indefinitely.)
We want normal users to move past "experimental IPv6" towards "production
IPv6".
I want that too. What I object to is a denial-of-service attack on people who
find 6to4 useful, just because it doesn't work as well as IPv4 for services
that support both IPv4 and IPv6.
Keith
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