On Mon, Oct 7, 2019 at 3:32 PM Michel Py <michel.py@tsisemi.com> wrote:
> >> Michel Py wrote :
> >> When did you write this ? I read it before, just can't remember how long ago.
>
> > William Herrin wrote :
> > 2007. Half of IPv6's lifetime ago. It came out of an ARIN PPML thread titled "The myth of IPv6-IPv4 interoperation."
> > On one side of the argument, folks saying that the need to manage two configurations impairs IPv6's deployment.
> > On the other, an individual  whose thesis was the IPv6 could not have been designed to be backwards compatible
> > with IPv4 in a way that required no new configuration, just incremental, backward-compatible software upgrades.
>
> Why did you choose this route, instead of encapsulating the packet with the extended address into an IPv4 packet ?

I was out to prove a point. I needed a technique that, at least in theory, would start working as a result of software upgrades alone, needing no configuration changes or other operator intervention. If I couldn't do that, my debate opponent was right -- a greenfield approach to IPv6 made more sense despite the deployment challenge.

Map-encap, where you select a decapsulator (consult the map) and then send a tunneled packet (encapsulated) does some cool stuff, but it's a pretty significant change to the network architecture. Definitely not configuration-free.

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