The long-lasting block size dispute and the recent introduction of several new Bitcoin implementations highlighted that not all Bitcoin nodes apply the exact same rule – and, perhaps more important, that not all development teams apply similar policies when it comes to implementing these rules.
The development team behind Bitcoin Core , Bitcoin’s historic “reference client,” requires widespread community consensus before it implements rule changes such as raising the block size limit, while other changes are not held to the same standards.
Meanwhile, some Bitcoin forks, such as Bitcoin LJR , are generally accepted by the development community, while others, such as Bitcoin Classic , attract a lot of controversy. This is considered inconsistent by some.
But this difference can be explained. Certain rule changes, implemented in certain forks, impact the Bitcoin network very differently than others. Or more specifically: Certain rule changes impact very different layers of the Bitcoin network. And some of these rules changes can split the Bitcoin network while others cannot.
To clarify these differences, Bitcoin Core developer and Ciphrex CEO Eric Lombrozo recently proposed to tag the relevant layers in all Bitcoin Improvement Proposals. These are the four main layers on the Bitcoin network as specified in his BIP 123 , and the respective importance of consensus on each.
The Consensus Rules
The consensus rules are Bitcoin’s most important rules. They establish – among many other things – the amount of bitcoins included in the block reward, the mining difficulty, the type of proof-of-work required, and, indeed, the block size limit.
These rules are so important because they determine which blocks are deemed valid by full nodes. And if all full nodes apply the same consensus rules, it ensures they all maintain an identical copy of the blockchain.If different nodes apply different consensus rules, however, they risk accepting blocks […]
