How Ethereum Clients Work Together for Security and Consensus

Ethereum is a digital world where money works in new ways, and it's super smart. But how does it make sure everything is fair and nobody tricks the system? Well, imagine Ethereum as a team of superhero computers. They all work together to check that everything is okay and no one is playing tricks. This blog will show you how these computer superheroes team up to keep your data safe and make sure everything is awesome in Ethereum land. Let's jump in and find out!

What are Nodes and Clients?

Ethereum nodes are like club members in a virtual space. They're individual computers connected to the network, cooperating to monitor transactions, contracts, and blockchain events. Nodes hold a complete blockchain copy, sync with others, and ensure accurate data. They validate transactions, uphold network integrity, and sustain Ethereum's smooth operation.

The Ethereum network is structured into two distinct parts: the execution layer and the consensus layer. These two layers are managed by separate client software. In the discussion below, we'll use the terms "execution client" and "consensus client" to refer to these software components.

1. Execution Client:

   These clients execute the smart contracts and transactions on the Ethereum network. They validate and process the code contained within transactions to update the state of the blockchain. Examples: Geth, Nethermind, Besu and Erigon.

2. Consensus Client:

   These clients are responsible for participating in the consensus process to agree on the next valid block in the blockchain. They follow the Ethereum protocol rules to validate transactions, propose blocks, and achieve agreement with other clients. Examples: Lighthouse, Lodestar, Nimbus, Prysm and Teku.

When the Merge happens, Ethereum shifts to a different way of confirming transactions called proof-of-stake. The execution and consensus clients team up to make sure Ethereum's status is correct. The execution client handles transactions and smart contracts, while the consensus client makes sure everything is agreed upon. Together, they keep Ethereum running smoothly and securely

After the Merge, you can't use only the execution client. Both execution and consensus clients must run together for access to Ethereum. It's like needing two friends to open a special club – they both have to be there for you to join the fun.

Why is it important to have Client Diversity?

Having different software options (clients) following the same rules in networks like Ethereum is called client diversity. This variety, like Geth, OpenEthereum, and Besu for Ethereum, makes the network stronger and safer. If one client has a problem, the others can keep the network running smoothly. This diversity also encourages innovation, provides choices for users, and helps maintain a decentralized and strong network.

What these implementations have in common is they all follow a single specification. Specifications dictate how the Ethereum network and blockchain functions.

Types of Nodes

1. Full Node: A full node is like having the whole book. It has a complete copy of the entire Ethereum history, including all transactions and smart contracts. It helps check and confirm new transactions and keeps the network secure.
2. Light Node: A light node is like reading the summary. It doesn't store everything, but it can quickly check recent transactions and smart contracts by asking other nodes for information. It's useful if you want to use Ethereum but don't need all the details.
3. Archive Node: An archive node is like having every old newspaper. It stores the complete history, just like a full node, but also keeps old states of the Ethereum world. This can be useful for looking up past data, like checking the contents of an old smart contract.

Why should we run Ethereum nodes?

Running an Ethereum node has many benefits. Firstly, you can double-check transactions for safety. Secondly, you control your access to Ethereum's info, keeping things private. Thirdly, you help make Ethereum stronger and more spread out by supporting the network with your node. Plus, you can talk directly to smart contracts and learn how Ethereum really works. Also, you don't have to just trust the network – you can check things yourself using your own client.

What does the Execution Client Do?

1. Transaction Verification: Execution clients verify incoming transactions to ensure they're properly formatted and valid. They check details like the sender's signature and whether the sender has enough funds to carry out the transaction.
2. Gas Calculation: Clients calculate the amount of gas required for transaction execution. Gas acts as a fee and covers the computational resources needed to process the transaction.
3. Ethereum Virtual Machine (EVM): Execution clients have an Ethereum Virtual Machine (EVM) that interprets and executes the bytecode contained within smart contracts and transactions. The EVM is like a computer processor dedicated to running Ethereum code.
4. Smart Contract Execution: Clients execute the code of smart contracts on the EVM. This involves following the instructions provided by the contract's code, updating data and balances, and interacting with other contracts if necessary.
5. State Changes: Execution clients modify the state of the Ethereum blockchain based on the outcomes of transactions and smart contract execution. This includes updating account balances, contract storage, and other relevant data.
6. Event Emission: Execution clients facilitate the emission of events from smart contracts. These events are like notifications that certain actions have occurred, and they can be monitored by applications and users.
7. Error Handling: If a transaction or contract execution encounters errors or exceptions, execution clients manage these situations and ensure that the blockchain remains consistent.
8. Gas Management: Clients track the gas used during transaction and contract execution. If a transaction runs out of gas, it is reverted, and any changes to the state are undone.
9. Interactions with External Data: Execution clients can interact with external data sources through various mechanisms, enabling smart contracts to access information beyond the blockchain.

What does the Consensus Client Do?

1. Block Proposals: When it's time to add new transactions to the blockchain, the consensus client helps some nodes propose blocks. These blocks contain a list of transactions that need to be added.
2. Checking and Voting: Other nodes in the network, including the consensus client itself, check the proposed blocks to make sure they're correct and follow the rules. It's like having a bunch of people review a suggestion before deciding if it's good.
3. Agreement Process: Nodes discuss and agree on which block should be added next. The consensus client helps everyone come to an agreement, so they all choose the same block.
4. Final Decision: Once most of the nodes agree on a block, the consensus client makes that block official. It's like putting a stamp on a decision to show that it's the right one.
5. Avoiding Confusion: The consensus client prevents confusion by making sure everyone in the network is on the same page. It stops any disagreements and makes sure the blockchain's history is clear and agreed upon by everyone.
6. Security Measures: The consensus client also helps prevent any bad actors from trying to cheat or disrupt the network. It makes sure that everyone follows the rules, and if someone tries to break the rules, they'll be caught.
7. New Chain Parts: As new blocks get added, the consensus client helps make the blockchain longer and keeps track of the correct order of events.

Validators

People who operate Ethereum's computer system can become validators by depositing 32 units of Ethereum's currency (ETH) into a special account. Once they become validators, they receive a helper program that comes with Ethereum's main computer program. This helper program assists with important tasks like confirming certain actions (attestations) and suggesting new actions to add to Ethereum's records (block proposals). Validators have the opportunity to earn more Ethereum as a reward for doing well and following the rules, but they could also lose some ETH if they don't play fair. Being a validator also makes them eligible to propose new actions for Ethereum

How do Light Client Work?

When Ethereum started using a different way for computers to agree on things (called proof-of-stake), they made some changes to help smaller computers work better. They created new tools for what we call "light clients." Here's how it works:

Imagine there's a group of important people (validators) who sign their names on a paper that says everything is okay. Every 1.1 days, a random group of 512 of these important people forms a team (sync committee). They sign their names on a paper that talks about recent things happening. This paper also says who from the team signed and who didn't. The paper also gives a list of names of the people who will sign the next paper.

Now, if you're a smaller computer, you don't need to get the big paper with all the details. You just need the part with the signatures and the list of names. This helps you know that everything is good without getting all the extra stuff.

On another part of the computer work, there isn't one exact way to make a small computer understand everything. Sometimes, a small computer can be like a "light" version of a big one. It has some abilities but doesn't do everything. It can quickly check if everything is okay by asking a bigger computer. Or, it can be even simpler and mostly ask for help from a special service to understand things.

In the end, these changes make it easier for smaller computers to stay updated with the latest Ethereum news without having to do all the heavy work. They get the important parts without downloading everything.

Why are Light Client Important?

Light clients are important because they let users check information they receive instead of blindly believing it. They use only a small amount of computer power, memory, and storage, which is much less than a full computer. Light clients are like a "lite" version of the full thing, and they can run on mobile phones, apps, or even in web browsers. They help people access Ethereum without needing to fully trust someone else to give them the right info.

Here's an example to make it simple: Imagine you want to see how much money you have in your account. You ask an Ethereum computer for this info. It checks its own records and tells you. But if you can't check it yourself and have to ask someone else, you have to trust them. Light clients fix this. You still ask someone else, but they give you a proof along with the info. Your light client checks the proof and the info from the main Ethereum group. This way, Ethereum itself makes sure you're getting the right info, not just a random person.

Why Execution Layer is Overwhelmingly Dominated by Geth?

The execution layer of the Ethereum network, responsible for transaction processing, smart contract execution, and maintaining the blockchain's state, is predominantly and significantly influenced by the widely used Go Ethereum (Geth) client. Geth plays a pivotal role in ensuring accurate and secure execution of transactions and smart contracts, contributing to the network's overall functionality. Its extensive adoption underscores its importance in supporting Ethereum's core operations and interactions, despite the value of maintaining a diverse client ecosystem for enhanced resilience and innovation.

Go Ethereum (Geth) offers as both an Ethereum client and a consensus client:

As an Ethereum Client:

1. Transaction Processing: Geth processes and validates transactions, ensuring accurate execution of actions on the Ethereum blockchain.
2. Smart Contract Execution: It runs the Ethereum Virtual Machine (EVM), enabling the execution of smart contracts and decentralized applications.
3. State Management: Geth manages the state of the Ethereum blockchain, keeping track of account balances, contract storage, and data changes.
4. Network Communication: Geth communicates with other nodes through Ethereum's peer-to-peer protocol, sharing information about transactions, blocks, and network activities.
5. JSON-RPC API: Geth exposes a JSON-RPC API that allows developers to interact programmatically with the Ethereum network, facilitating various functionalities and data retrieval.
6. Syncing: It helps new nodes synchronize with the Ethereum network, ensuring they have the most up-to-date blockchain data.
7. Ethereum Improvement Proposals (EIPs): Geth incorporates changes proposed by EIPs, contributing to the evolution and improvement of Ethereum's protocol.
8. Private Networks: Geth supports the creation of private Ethereum networks for development and testing purposes.

As a Consensus Client:

1. Proof of Work (PoW) Validation: Geth participates in validating and agreeing upon new blocks through the PoW consensus mechanism, ensuring the security and integrity of the blockchain.
2. Proof of Stake (PoS) Beacon Chain Interaction: In Ethereum 2.0's PoS mechanism, Geth interacts with the Beacon Chain, contributing to consensus activities like attestation and block proposal.
3. Block Verification: Geth verifies the validity of proposed blocks, ensuring they adhere to the consensus rules and Ethereum protocol.
4. Fork Resolution: It assists in resolving forks by selecting the longest and most valid chain, maintaining network stability.
5. Participation in Network Activities: Geth actively communicates with other nodes, participating in the dissemination of new blocks and transactions, and contributing to the overall consensus process.

This blog explored how Ethereum's network works, including how transactions and contracts are managed, and how everyone agrees on what's valid. It highlighted the key role of Go Ethereum (Geth) in making all of this happen smoothly. Geth helps process transactions, ensures agreements, and keeps things secure. It's like the glue that holds Ethereum together, and its open teamwork helps keep everything running well.