Earlier quoted context omitted.
That problem is quite common on the internet in general. Just think how common ftp still is! We constantly use public networks and then have to mitigate the fact that the packets are public. It would be better to treat encryption like a peering arrangement. When there is sufficient traffic between two large networks all packets should be routed via an encrypted tunnel.
While I generally agree with the concept, encryption isn't free, and will break pretty much every routing protocol used. It's easy enough to get a tunnel through transit when you control both ends, but neither the hardware nor the software that actually runs the peers supports it in any way. You'd have to set the link, then encrypt on top of that, costing a ton of cpu cycles, bandwidth overhead, and requiring somethi…
I would propose creating single VPN tunnel between these corporate networks that all traffic destined for the other network is routed down. Just join individual private networks with encryped tiunnels. This would be completely transparent at the client level as the data would just follow a different path. It would avoid the startup cost of SSL or the higher CPU requirements of symmetric encryption. Such a setup could be required as a contract/tendering/supplier requirement.
Really if you have two companies that are sending data that may be sensitive why would you want any of the packets to ever be sent in plan view? Client side standards will never give a complete gurantee of that. It is much more enforcable to add the security at the network level.