Question About Blockchain consensus mechanisms

[theunsgk]

Hi. I am researching blockchains, and I have been helped here before, but now since thinking a bit, I am wondering what exactly consensus mechanisms do. I have read articles explaining it, but I feel they just explain the currently used ones. I am wondering what it is designed to actually do in a crypto/blockchain situation.

So to state my question more simply: If I want to "make" a consensus mechanism, what does it have to do to be one?

To clear up what I currently think it has to do: The consensus mechanism makes sure no node can spam the blockchain with blocks in order to control the chain but still be fair to nodes who have invested more resources than other nodes. So from my understanding this is what helps keep the blockchain "honest".

I hope my question is clear, and relevant to this forum.

Thx in advance

[jackg]

There are two forms of consensus mechanisms at play with a lot of blockchains.

One is where miners essentially decide what protocols they're happy supporting in their blocks and this is normally done by adding additional data with a binary option of for or against somewhere inside data for the block. After a certain proportion of blocks support a certain method, it gets added to the generic consensus algorithm of nodes and other applications at some point. Most of the blocks are mined by a few pools so there's normally a 90%+ consensus on things that are added afaik.

The consensus algorithm with nodes works a similar way but they are preconfigured to accept and propagate certain transactions, I'm not sure whether they have an option to reject blocks with non compliant transactions though if they're on the longest chain - I think there was protection against this to stop a chain split.

[theunsgk]

There are two forms of consensus mechanisms at play with a lot of blockchains.

One is where miners essentially decide what protocols they're happy supporting in their blocks and this is normally done by adding additional data with a binary option of for or against somewhere inside data for the block. After a certain proportion of blocks support a certain method, it gets added to the generic consensus algorithm of nodes and other applications at some point. Most of the blocks are mined by a few pools so there's normally a 90%+ consensus on things that are added afaik.

The consensus algorithm with nodes works a similar way but they are preconfigured to accept and propagate certain transactions, I'm not sure whether they have an option to reject blocks with non compliant transactions though if they're on the longest chain - I think there was protection against this to stop a chain split.

If Im being honest I dont really understand what you are saying.
What I try to understand is thus that with the first one miners decide between a few methods. Which methods though? And does it change every block?

Also with the second one, as I understand the transactions are sent to every single node and verified there before being added to a block?

[odolvlobo]

Hi. I am researching blockchains, and I have been helped here before, but now since thinking a bit, I am wondering what exactly consensus mechanisms do. I have read articles explaining it, but I feel they just explain the currently used ones. I am wondering what it is designed to actually do in a crypto/blockchain situation.

In my view, Bitcoin is a set of rules at its core. These consist of:

• 1. rules that specify the protocol,
• 2. rules for maintaining the integrity of the system, and
• 3. rules that create an incentive for participants to maintain the integrity.

The "consensus mechanism" might be described as #2 and #3 and how they interact.

In Bitcoin, the consensus mechanism is called "proof-of-work" because it is based on the concept of proof-of-work. The Bitcoin rules ensure that a miner must incur significant costs in order to publish a valid block. One effect of these costs is to discourage the publication of blocks that make changes to the block chain.

[theunsgk]

Hi. I am researching blockchains, and I have been helped here before, but now since thinking a bit, I am wondering what exactly consensus mechanisms do. I have read articles explaining it, but I feel they just explain the currently used ones. I am wondering what it is designed to actually do in a crypto/blockchain situation.

In my view, Bitcoin is a set of rules at its core. These consist of:

• 1. rules that specify the protocol,
• 2. rules for maintaining the integrity of the system, and
• 3. rules that create an incentive for participants to follow these rules.

The "consensus mechanism" might be described as #2 and #3 and how they interact.

Ok.. thx for the answer, it makes more sense now

[jackg]

If Im being honest I dont really understand what you are saying.
What I try to understand is thus that with the first one miners decide between a few methods. Which methods though? And does it change every block?

Also with the second one, as I understand the transactions are sent to every single node and verified there before being added to a block?

The methods often stay the same but new ones can be added by the devs and there's a default recommendation miners can mine with but a lot of miners and pools might decide by themselves when things are more stable to be supported.

Transactions don't need to be verified by many nodes before reaching a miner but it has to be verified by the node and miner mining that block. Nodes are used to store the blockchain and unnconfirmed transactions and distribute them, the miners are used to make new blocks and normally send them to a node so thst it can advertise it's found the block to other nodes.

[hatshepsut93]

As its name suggests, consensus mechanism guarantees that all nodes are agreeing on the state of blockchain. The point of blockchain is all nodes having the same exact database without any single source of truth. This is achieved by putting transactions into blocks, instead of just adding them to the database independently, and spacing those blocks in time with mining. Bitcoin blocks are targeted to be created every 10 minutes, if they were appearing faster, there would be more conflicts about which block is the latest, so recent confirmations would be a bit less reliable.

It's a misconception that the biggest achievement of mining is "securing the network" or "keeping it safe fro attacks". The real biggest achievement is synchronizing a global database that is organized as a peer-to-peer network.

[theunsgk]

As its name suggests, consensus mechanism guarantees that all nodes are agreeing on the state of blockchain. The point of blockchain is all nodes having the same exact database without any single source of truth. This is achieved by putting transactions into blocks, instead of just adding them to the database independently, and spacing those blocks in time with mining. Bitcoin blocks are targeted to be created every 10 minutes, if they were appearing faster, there would be more conflicts about which block is the latest, so recent confirmations would be a bit less reliable.

It's a misconception that the biggest achievement of mining is "securing the network" or "keeping it safe fro attacks". The real biggest achievement is synchronizing a global database that is organized as a peer-to-peer network.

Thx for the answer! It is definitely helping to let me understand blockchain

[KingsDen]

Can we see this concept?
We all need to secure a single treasure. We don't know one another and we don't trust one another (trustlessness). Yet, everyone has a gun to secure the treasure. The one with the highest gun power can kill faster than others, but cannot kill everyone at the same time.
So the consensus gives the one with higher hash power (PoW) or higher stake(PoS) the upper hand and while still checked by the remaining community.
Blockchain is a trust to the trustless system.

[Trojane]

You're really not getting your own questions seriously...
I think you should know what the word CONSENSUS means before you keep being curious, yeah!
 You've explained it below that it's said to trim or reduce the level of block chain spam, yes that's what it does; I'm not really seeing it as being honest anyways, why? The block chain is already very cumbersome, so if unnecessary spam is allowed on it by every shitty head dummy, then it's gonna almost be impossible to download the whole blockchain and this will somehow give rise to reduction in coin value(Bitcoin).
Satisfied with that?