Peter Ford wrote:
If one really believes in end to end architectures, then one probably
would want generalized protocols for supporting hosts telling the
network what to do wrt opening holes at NATs/Firewalls for inbound
traffic.
Actually, if one believes in the E2E arch (more specifically, the STD
documents), we should admit that:
- NATs are _designed_ to make everything behind them
look like a single host
- they work fine exactly where that's sufficient
- they break very badly for EVERY new protocol that
coordinates ports or IP addresses in-band, and in any
other case where everything behind them does NOT
want to work like a single host
A generalized protocol for opening holes would fundamentally alter the
Internet architecture (as specified in the STD docs) to _require_ path
setup, which defeats dynamic routing, and, more specifically, the
fundamentally connection-free property of datagram service.
Joe