NewsBlogWhat Is a Node in Blockchain?

What Is a Node in Blockchain?

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Algorand Foundation

Blockchain nodes serve as the backbone of decentralized networks. They contribute to the storage, verification, consensus, and synchronization of transactions. Nodes differ in their roles and responsibilities, but by working together, they ensure the reliability and security of a blockchain system. No single node is solely responsible for or essential to a blockchain’s operation. Data is spread across the network, so regardless of whether a node goes offline, the online nodes will continue to communicate and process transactions on the blockchain. 

What is a node in blockchain?

In the context of blockchain, a node refers to a device or computer that participates in a network. Different types of nodes have different functions; for example, some nodes maintain a copy of the entire blockchain ledger, while others simply help validate transactions and keep the network secure. Each node acts as a building block for the decentralized nature of blockchain technology. 

Node types will vary depending on the blockchain in question. Algorand uses a pure proof-of-stake (PPoS) mechanism and distinguishes between two types of nodes: Relay nodes and participation nodes. These two types of nodes allow the blockchain to optimize decentralization and maintain high transaction speeds.

Why does a blockchain need nodes?

Blockchain networks rely on nodes for three essential reasons: Decentralization, consensus, and security.

Decentralization 

Nodes collectively form a decentralized network, which eliminates the need for a central authority or intermediaries. This decentralization is a core characteristic of blockchain, as it ensures trust, transparency, and resistance to censorship or control by any single entity.

Consensus

Nodes play a critical role in achieving consensus in a blockchain network. Through a consensus mechanism, such as Algorand’s PPoS, nodes validate transactions and ensure agreement on the state of the blockchain. A consensus mechanism helps maintain the integrity of the ledger and prevent double-spending or fraudulent activities.

Security 

Nodes contribute to the security of the blockchain by verifying and validating transactions. The distributed nature of nodes makes it extremely difficult for malicious actors to manipulate the blockchain's data. Additionally, as some nodes maintain a copy of the entire blockchain, they contribute to its immutability, ensuring that past transactions cannot be altered.

How do blockchain nodes work?

Blockchain nodes collaborate to maintain the network's integrity and perform several functions.

Storing and verifying transactions 

Some nodes store a copy of the blockchain, which contains a record of all transactions. These nodes validate incoming transactions, ensuring they adhere to the network's predefined rules and consensus algorithm. By verifying transactions, these nodes contribute to the prevention of fraud and unauthorized activities.

Propagating and broadcasting transactions

When a new transaction occurs, some nodes propagate it to other nodes in the network. This process ensures that all nodes have access to the most up-to-date information, allowing for synchronization of the ledger across the network. When a transaction occurs on Algorand, relay nodes work to propagate the data across the network. 

Participating in consensus

Nodes can choose to actively participate in the consensus mechanism of the blockchain network. The way this works will depend on which consensus mechanism is employed. In the case of Algorand’s PPoS, participants register their stake online to participate, but the stake never leaves their wallet during consensus.  

Maintaining the network 

Nodes communicate with each other to exchange information about transactions and blocks in order to maintain a synchronized and consistent view of the blockchain. In the case of conflict, nodes work together to resolve discrepancies and achieve consensus on the blockchain.

Types of blockchain nodes on Algorand

Algorand uses two types of nodes to achieve decentralization and scalability: Relay and participation nodes. These nodes are designed to maintain high transaction speeds and enable global adoption. The faster a message can be propagated through a network, the better it is for users. 

Relay nodes 

Relay nodes are always connected to other relay nodes and participation nodes. They are an indispensable part of the protocol because they deliver important information to all the other network participants. Relay nodes ensure other nodes obtain the same block information and remain up-to-date, so the network is always synchronized. Relay nodes distribute data and check for duplicate transactions. These nodes are designed to support and process large data loads. 

As of 2023, there are around 110 relay nodes on the Algorand network.

Participation nodes 

Participation nodes participate in consensus. They help to maintain decentralization, validate transactions, and enhance overall network security. Participation nodes don’t relay information. Instead, they rely on relay nodes to communicate and share updates. No participation node will use a relay node unless it is specifically instructed to do so when it is set up. Please note: While it is also possible for relay nodes to participate in consensus, it is strongly discouraged and less secure. 

Anyone can run a relay or participation node to participate in the Algorand consensus protocol.

The total number of participation nodes can be found on the Algorand Metrics Dashboard.

Archival and non-archival nodes

Nodes can be configured as archival or non-archival. Archival nodes store the entire ledger, while non-archival nodes store only a snapshot of the ledger, which in Algorand’s case is the last 1000 blocks. Relay nodes are always archival. On the other hand, while participation nodes can be archival, they should be set up as non-archival and only be used for participation. 

For the possible configurations of nodes on Algorand, visit the Developer Portal.

How to run a node

Anyone can run a relay or participation node. You will find the basic steps on how to install and run a node on the Developer Portal. At present, anyone can run a relay node, but they will need permission from the Algorand Foundation. 

Algorand one-click nodes

Algorand recently launched AlgoRun one-click nodes. The AlgoRun tool simplifies setting up and starting an Algorand mainnet node. It requires Python 3.10+, Docker, and Pipx (also prerequisites for AlgoKit) and can be installed on Mac, Linux, or Windows. It supports the setup of a non-participation node, but further steps are required to participate in consensus. Please note: AlgoRun is still in its experimental stage.

Watch: AlgoRun provides 1-click node running, Algorand Proof of State

Further reading: 

What is Algorand’s consensus protocol?

Algorand’s network architecture overview

Algorand’s pure proof-of-stake protocol

Algorand node types 

FAQs: Relay nodes

Photo by Clint Adair on Unsplash

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