Re: [Softwires] I-D Action:draft-donnerhacke-softwire-ipv6-6to4-01.txt

Brian E Carpenter <brian.e.carpenter@gmail.com> Fri, 28 May 2010 10:29 UTC

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Date: Fri, 28 May 2010 22:29:17 +1200
From: Brian E Carpenter <brian.e.carpenter@gmail.com>
Organization: University of Auckland
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To: draft-donnerhacke-softwire-ipv6-6to4@tools.ietf.org, softwires@ietf.org
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Subject: Re: [Softwires] I-D Action:draft-donnerhacke-softwire-ipv6-6to4-01.txt
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>       6to4 prefixes more specific than 2002::/16 are allowed to be
>       propagated in native IPv6 routing, as long as the more specific
>       matchs exactly the mapped most aggregated IPv4 route originated by
>       the same AS. 

This is a really, really bad idea, for the reason given in RFC3056:

      6to4 prefixes more specific than 2002::/16 must not be propagated
      in native IPv6 routing, to prevent pollution of the IPv6 routing
      table by elements of the IPv4 routing table.

That is a much more important issue than the fact that 6to4 doesn't work
well for users whose ISPs haven't deployed a 6to4 relay (and announced 2002::/16
locally). ISPs do need to pay attention to filtering rules for 2002::/16
announcements.

   Brian