Re: 6rd - Rapid Deployment on existing IPv4 infrastructures - a newapproach

[Remi Denis-Courmont <rdenis@simphalempin.com>]

On Wed, 13 Feb 2008 14:22:01 +0100, Rémi Després <remi.despres@free.fr>

wrote:

> > The issue is with *cascading* routers. With no bits to do

> > routing within a site, if bridging is not possible, there

> > is no choice but to use NAT.



> There is IMHO a better alternative:  where no IPv6 prefix is

> available, like behind a cascading router in a /64 site, use

> another available tool.

> (Teredo, tunnel broker etc, are IMU availble precisely for this).



Neither Teredo nor TSP are suited in that case. You'd have to go to the

Internet to reach hosts from the same site, but within different subnets.



There is a reason why native IPv6 access and normal 6to4 are giving more

than 64-bits. It's precisely because the solution to this problem is

Prefix-Delegation.



> > Where is the complexity in shifting some bits?

> Right, "shifting bits" is simple.



> It works if each ISP hasonly one RIR-provided prefix for all

> its customers,  but *only in this case*.



Makes no difference how many prefixes the ISP has. In any case, the

ISP-side endpoint needs to know the prefixes so that it cannot be abused by

external users from other ISPs. Moving this issue away from the 64rd ISP

endpoint and its addressing scheme to yet another box (a firewall, right)

is arguably even more complicated, in fact.



> Personally I don't know how many v4 prefixes Free has,

> and plans to use. But, as you know,  ISPs tend to get

> their v4 address space piece by piece.



So? 64rd cannot avoid the problem anyway.



-- 

Rémi Denis-Courmont

http://www.remlab.net