Honk if you like Hub & Spoke

When I first heard that a world with millions of blockchains is possible, I kind of lost my mind. Blockchains/shards/roll-ups, whatever you call them, there may very well be millions of them. A world with billions of computers sounded impossible in 1960, too.

In order to get there and get there securely, we are going to need interoperability hubs.

Hub & Spoke

Hub & Spoke scales linearly, point to point (or pairwise) scales quadratically

Where n is the number of blockchains, the number of inter-blockchain connections needed for each model is shown below:

I would chart this, but it looks ridiculous
Ok here’s a chart

For 4 blockchains, this isn’t an issue, but even once you get to 10 chains, it starts to look pretty unfavorable for point to point.

It quickly becomes obvious that we are going to need hubs for inter-blockchain communication whether we like it or not. Just like we have multi-chain whether we like it or not.

Examples of Hubs

Airports are hubs
Cities are hubs
National economies are hubs
The internet in 1993. If you zoomed in on the countries in this picture, you’d see universities, optic fiber outlets and then household wifi routers. Hub and spoke models allow for fractal scaling. Note the internet could have been designed much better to afford hubs, and we have a chance to design blockchain interop to enable this from the beginning.

Perks of hubs

Hubs are routers

We need a decentralised version of her

Translation

Hubs increase the security of large networks

Monitoring (Contagion containment)

Imagine dealing with nuclear meltdown if all these dials and valves were in different rooms

This secured 12 chains from the compromised Terra network, and from bridging axlUST and axlLUNA between uncompromised networks. With a point to point model, there would potentially have needed to be 72 governance votes to close down all the channels. More likely, in a well designed point to point model, only 12 votes would be needed — one for each chain which hosts bridged Terra assets. In a crisis like the one that brought down Terra, 12 votes is still much much slower and harder to keep track of than 1.

What if a hub is compromised?

Just because you break into a bank, doesn’t mean you get all the assets.

The core insight here is that in a point to point system, the L1 blockchains which are being connected are actually the hubs. Most blockchains are not designed to be interoperability hubs, and to use them as such is a mistake. The way forward seems quite clear to me — that we need infrastructure which is designed for interoperability from the ground up.

Upgrades

Liquidity fragmentation

Imagine needing to individually value and provide liquidity to 20 different wrapped Bitcoins, bridged from 20 different chains. Add in double wrapping or triple wrapping (multi-hop bridging) and you quickly get thousands of different wrapped assets which are all meant to be interchangeable. Tracking the security risks is a nightmare.

How many times have you been wrapped, Biff?

A hub model, in comparison, never allows a time traveller to meet themselves. It only allows one bridge-wrapped BTC or USDC on each chain. To send it to another chain, you send back to the hub, then the hub sends to the destination.

Multi-hub (sharded interop)

Looking a bit like mapofzones.com (or maybe what mapofzones should look like)

In my view, the ideal technology is one which allows the market to decide how many hubs should exist, and what chains are connected to each. This means we need permissionless, decentralised, generalised interoperability technology which supports a hub model.

Axelar is the only real contender for this. Or at least, they have a head start, and a serious advantage in their team composition. Their founder Sergey designed low level software for dynamic routing of internet packets, and then designed and launched Algorand. You couldn’t really ask for a better qualified person to solve this problem.

Interop hubs need to happen

Next, I’ll be reviewing a paper on overlay networks for the internet. I’ll liken the scaling issues of blockchains to the internet infrastructure and sow seeds of hope that we can scale this thing.

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