[tjgq]

I think it's a wonderful thing that the TCP/IP model (as originally envisioned) does not preclude endpoints from implementing their own transport protocols on top of IP, irrespective of what the rest of the network uses.

Unfortunately, reality has conspired against this possibility in two ways: NAT boxes, and the fact that transport protocols are implemented in the kernel on most operating systems (hence, an application cannot use its own transport protocol easily).

The deployment of IPv6 is a real chance to, at least, fix the first of these problems. Let's hope it does.