Re: shim - transport/app communication

[Iljitsch van Beijnum <iljitsch@muada.com>]

On 19-mrt-05, at 22:32, Baker Fred wrote:

> > the only thing an application should depend on here is that it 
> > supports IPv6 addresses

> If I could make a humble request here...

> Could we please manage to avoid the worst of the layering faults we 
> committed in the IPv4 Internet? The thing that has made NAT hard and 
> made applications break crossing a NAT was that the applications know 
> something about addresses. Let's not do that with IPv6 applications.

It's already done. The RFC 3493 API extensions require an application 
to know about IPv6, if only because they have to specify AF_INET6. In 
theory, that's it, but in practice it's much worse because an IPv6 
application really needs to cycle through all available addresses, 
which IPv4 applications rarely do. Then there is the whole IPv4-mapped 
implementation debacle that makes writing (portable) applications that 
support both IPv4 and IPv6 rather tricky.

The only real solution that I can see here is yet another API that 
moves address resolution out of the application, and completely hides 
the IP version from the application.

The good news is that there should be some time to get it right before 
we need to move to whatever comes after IPv6.  :-)