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Re: draft-despres-v6ops-6rd-ipv6-rapid-deployment



On Tue, 11 Mar 2008, james woodyatt wrote:
It seems to me that 2002::/16, the 6to4 prefix, can be regarded as a special case of 6rd ISP prefix allocated by IANA and unassigned to any particular organization. What 6RD does is allow each ISP to define their own 6to4-like routing domain, provided that CPE functions are properly loaded with the 6rd ISP prefix to use as distinguished from the 2002::/16 prefix assigned by IANA.
The draft defines a new DHCPv4 option used by 6RD ISP to configure 
6RD-enabled CPE, i.e. hosts or dual-stack IPv4/IPv6 routers with 
6RD-tunneling functions.  I very much doubt that getting vendors of consumer 
retail CPE, e.g. host operating systems, consumer routers, etc., to adopt 
this DHCP client feature will be easy.  For that reason, I don't expect 6RD 
to be deployable except with provider-provisioned CPE.
Agreed about deployment caveats and that part of 6rd being a trivial 
extension of 6to4 concept.  That'll no longer be the case if you don't 
embed the complete v4 address in IPv6 prefix.
I'd be opposed to specifying a mechanism which would require an ISP to 
use a whole /32 prefix for this because that would screw up existing 
allocations and would deter ISPs from applying this mechanism.
One major point to consider in this context is whether you want the 
hosts/routers to be able to communicate directly with each other (in 
which case they also need to know how to calculate the IPv4 address if 
the full IPv4 address is not provided in the IPv6 prefix) or whether 
it's sufficient to just tunnel everything to the ISP's IPv6 
aggregation boxes.
The former is more difficult to generalize but provides better p2p 
traffic optimization.
The latter approach and specifically how you could do a partial map 
map from subset of v4 to v6 was described in 2003-2004 around Section 
5.3 of: http://tools.ietf.org/html/draft-savola-v6ops-conftun-setup-02 
This also supports multicast without a problem.
--
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings