Networking Kid / Layers As A Way Of Thinking

How Restraint At The Centre Made Change Possible

The network was kept simple so that the edges could be clever.

There is a principle running through this design that is easy to state and hard to appreciate until you have seen the alternative in action. Keep the middle of the network simple and put the cleverness at the edges. The equipment in the middle should do one job well, which is moving pieces onward, and should be spared any responsibility for understanding, guaranteeing or improving what those pieces happen to contain. The participants at either end take on the harder work of reliability, ordering, retrying and meaning, because they are the only ones who actually care about the outcome.

The benefit is that innovation does not require coordination. If the cleverness lived in the middle, then every new idea would need the agreement and the upgrading of an enormous amount of equipment owned by an enormous number of unrelated parties in countries with nothing in common. Because the cleverness lives at the edges, two participants can agree on something new entirely between themselves and simply start doing it tomorrow, and everything in between will carry it faithfully without needing to know, approve or even notice what it is carrying.

This restraint also has a defensive dimension worth naming at the level of principle. When the middle of the network does not need to understand the contents of what it carries, the contents can be protected from end to end without breaking the carrying at all. Privacy and integrity become properties the two participants can arrange between themselves, rather than favours they must request from every organisation whose equipment happens to sit along the path that day. A design choice made for flexibility turned out to underwrite trust as well.