Shipping Containers

IP (Internet Protocol) packets are like shipping containers. Or more precisely, intermodal containers. They are absolutely standardized. And can carry almost anything. The term standardized means they can be used across different modes of transport, without reloading their cargo.

Sounds like IP, right? From my laptop WiFi card to the access point, then via Ethernet to the router, then via a DSL phone line, to an Ethernet infrastructure and finally to a fiber optic long distance cable. You can even insert a microwave or laser-based link in between and nobody will notice. And nobody cares, since all the links are engineered to carry the IP packets. In a similar fashion the ships, trains, trucks are engineered to carry the intermodal containers.

There is only one case when the intermodal containers are not used: air cargo.

And the reason is simple: they are too bulky and too heavy. The nature of air transport is that is has to have as little overhead as possible. Otherwise it will not fly. Both physically and business - wise. Even assuming we build an airliner capable of accommodating an intermodal container. It would simply burn way too much fuel to carry this bulk around. The economics of air transport dictate us using something else: either a ULD (for small items), which is also standardized, or special types of aircraft like an Antonov AN-124 or AN-225 for special cargo.

The same logic applies to design of low power wireless infrastructure. If we want something that really flies, we need as little overhead as possible. And it simply pays to repack the payload at the gateway to a format that has lower overhead and flies effortlessly over wireless links.

In system design, physics simply cannot be ignored.