Honk if you like Hub & Spoke

Hub & Spoke

Hub & spoke is where all messages between parties pass through a routing hub. It means that you need to secure far fewer connections and is much more tidy to monitor and upgrade.

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

At scale, the number of cross-chain communication channels needed is drastically larger in a point to point (pairwise) network than in a Hub & Spoke one.

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

Examples of Hubs

Hubs are used all through society, from airports, to elevators, living rooms, national currencies, power stations, and sub DAOs.

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

Not only are hubs an inevitability, we should look forward to them. They provide specialised solutions to a number of networking problems which shouldn’t be fulfilled by the base blockchains or rollups.

Hubs are routers

Imagine the lady by the telephone switchboard. You can tell her who you want to speak to, and she connects you up with their line. An interoperability hub for blockchains needs to do the same thing. It needs to forward a message, along with some security guarantee.

We need a decentralised version of her

Translation

Now imagine if she could translate speech between speaker and listener in real time. This is what Axelar does. Translating messages between virtual environments (EVM → CosmWasm) is computationally much cheaper using low-level code at the core layer of an interop protocol, rather than doing translation inside another smart contract virtual machine.

Hubs increase the security of large networks

A common criticism of hubs is that they are single points of failure, and therefore harmful to security. Contrary to many people’s intuitions, in a large system the use of hubs is beneficial to security.

Monitoring (Contagion containment)

Take the Terra collapse as an example. Axelar network is an interoperability hub, connecting many chains. During the meltdown, Axelar passed a single governance vote which froze all messages from the Terra blockchain within 30 minutes.

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

What if a hub is compromised?

The intuitive risk with a Hub model is that when you hack a hub, you can hack all the chains it is connected to. There is more nuance to this point, however. For example, Axelar enables the community to set hub-wide rate limits per asset and per chain, so that a hacker would not be able to mint infinite axlBTC on every chain. A similar protection is basically impossible for a point to point system, or at least it would require stricter limits while in a healthy state in order to achieve the same level of damage control when things go wrong.

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

Upgrades

Even 130 IQs can probably see that upgrades to cross-chain communication channels are much cleaner in a hub and spoke network. Easier to coordinate, govern, implement. This is a security benefit and allows faster iteration.

Liquidity fragmentation

This is a buzzword that is thrown around a lot in multi-chain. In a point to point system, depending on the path that you take, you get different assets with different security characteristics. Most blockchain ecosystems are already seeing this issue.

How many times have you been wrapped, Biff?

Multi-hub (sharded interop)

Once you get to 100 chains, you probably want more than 1 hub. Think of adding hubs as a decentralising vector in a system which is becoming too ordered. They are a tool which can be added or removed to achieve a balance between two dystopias: chaos (warring tribes) and order (imperialism).

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

Interop hubs need to happen

There’s a lot of lyrical about cross-chain security going around. Much of the dialogue is lacking vision of a truly scaled multi-chain world. Up until this point, I believe that the necessity of interop hubs has been neglected. They are going to be a core part of this ecosystem and should be considered from the get go. Axelar are tackling this head on, and have built a sound blueprint for scaling this internet of blockchains.

--

--

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store
0xpostman

0xpostman

Cross chain desperado loose in the wireld