Blockchain technology has revolutionized the way we think about decentralized systems and secure data storage. However, as the adoption of blockchain grows, issues of scalability, transaction throughput, and efficiency have become increasingly prominent.

To address these challenges, the concept of blockchain layers has emerged. This layered architecture separates the core blockchain functionality from various scaling solutions and application layers, enabling improved performance, lower costs, and wider adoption.

In this article, we’ll explore the different layers of blockchain technology and how they work together to create a more robust and scalable ecosystem.

Types of Blockchain Architecture

Blockchain technology, renowned for its decentralization and security, operates within various architectural frameworks. These frameworks are often categorized based on access permissions, and cater to diverse needs and applications. The three main types of blockchain architecture are: 

1. Public Blockchains

Public blockchains operate with complete transparency. Anyone can participate in the network by running a node, validating transactions, and contributing to the consensus mechanism. This fosters trust and immutability, as the entire network maintains the ledger. Popular examples include Bitcoin and Ethereum.

2. Private Blockchains

Private blockchains, also known as permissioned blockchains, operate in a controlled environment with restricted access. Only authorized participants, pre-approved by a governing body, can join the network. This enables faster transaction processing and tailored functionalities for specific use cases. Examples include Hyperledger Fabric and Corda.

3. Hybrid Blockchains

Hybrid blockchains combine elements of both public and private blockchains, creating a unique architecture. They leverage the security and transparency of public blockchains for certain aspects, while utilizing the efficiency and control of private blockchains for others. This hybrid approach caters to scenarios requiring a balance between openness and control. Some examples of hybrid blockchain are Dragonchain, and EWF Baseline.

The Blockchain Layers 

The blockchain architecture refers to the elements or layers that comprise an entire blockchain system. Every layer has a distinct purpose, such as data storage, network connectivity maintenance, or systemic consensus. There are two methods for layering the blockchain network. The first one focuses on understanding its five layers and architecture. The second is a four-layered division based on the blockchain protocol. 

The Blockchain Architecture

1. Infrastructure or Hardware Layer

The foundation of any blockchain network lies within the infrastructure layer. This layer comprises a global network of computers, each acting as a node, that collaboratively maintains the decentralized system. The specific hardware used within this layer depends on the chosen consensus mechanism like PoW and PoS. 

• The Role of Nodes

• Validation

Nodes verify transactions based on predefined rules, ensuring their legitimacy before adding them to a block.

• Consensus

Nodes participate in the consensus mechanism to reach agreement on the validity of transactions and the current state of the ledger.

• Data Storage

Nodes maintain a copy of the entire blockchain ledger, ensuring decentralization and redundancy.

• Future of Infrastructure

The infrastructure layer is an ever-evolving landscape. Advancements in hardware technology, such as the rise of specialized blockchain hardware and cloud computing solutions, offer promising options for improved scalability and efficiency.  As blockchain technology matures, the infrastructure layer becomes more robust and adaptable, paving the way for a future of faster, more efficient, and secure decentralized networks.

2. Data Layer

The data layer is the beating heart of blockchain technology, that holds the most valuable asset which is the immutable record of all transactions. It’s where every interaction, from sending cryptocurrency to recording ownership of assets, is meticulously stored and secured. This layer functions like a digital ledger, ensuring transparency and security of information on the blockchain.

• Building Blocks 

The data layer isn’t a monotonous log of transactions. Instead, it utilizes blocks or cryptographic containers that hold a set amount of data. Each block contains:

1. Transaction data like sender, receiver, and amount transferred.
2. Timestamp that records the exact time the transaction occurred, ensuring chronological order.
3. Hash which is a unique digital fingerprint of the block’s data. Any alteration to the data results in a completely different hash, making it easy to detect attempts at tampering.

• Chain Reaction 

Blocks are not isolated entities. Each block references the hash of the previous block, forming a chronological chain. Imagine a train where each car (block) links to the previous one, creating an unbreakable sequence. This chaining mechanism guarantees immutability – once a block is added, it cannot be altered or deleted without modifying all subsequent blocks, which becomes computationally infeasible in a secure blockchain network.

• Merkle Trees

With growing blockchains, verifying every transaction within each block can become cumbersome. Merkle Trees, ingenious data structures, come to the rescue. They organize transaction hashes hierarchically, allowing for efficient verification of individual transactions without checking the entire block. This is similar to how a librarian quickly locates a specific book in a well-organized library using a cataloging system.

• Security at the Core

The data layer prioritizes security. Immutability, cryptographic hashes, and the distributed nature of blockchains work together to ensure the integrity of data. Any attempt to tamper with a transaction would require altering all subsequent blocks on the entire network, a near-impossible task in a secure system.

3. Network Layer

The network layer acts as the communication hub of the blockchain, facilitating the exchange of information that keeps the entire system functioning. It ensures smooth transmission of data between nodes. This is how the network layer works: 

• Transaction Broadcasting

A transaction, such as transmitting cryptocurrency, gets broadcasted to the network by the user who started it. Nodes on the network receive this broadcast and verify the transaction based on predefined rules, such as checking if the sender has sufficient funds.

• Propagation 

Once verified, the nodes propagate the transaction by relaying it to other nodes on the network. This ensures that the transaction reaches a large number of nodes, preventing any single node from manipulating or censoring the information.

• The Consensus Mechanism

The network layer works closely with the consensus layer. Verified transactions are presented to the consensus mechanism, which determines whether they are valid and should be included in the blockchain. Popular consensus mechanisms like PoW and PoS rely on the network layer for information about transactions.

• Balance Between Security and Efficiency

The Network Layer plays a critical role in balancing security and efficiency. A strong network ensures security by making it difficult for malicious actors to disrupt communication or manipulate transactions. However, robust security measures can also impact speed and scalability. As blockchain technology matures, advancements in network protocols and infrastructure are likely to address this balancing act, paving the way for faster and more efficient communication within the blockchain ecosystem.

4. Consensus Layer

Blockchain technology thrives on decentralization, but how do all these independent nodes scattered across the globe agree on the true state of the network? This crucial task falls to the consensus layer, the engine that ensures everyone is on the same page.

The Challenge of Decentralization

Imagine a room full of people trying to agree on what happened in a historical event, each relying on their own recollection.  In a decentralized network, nodes act as these individuals, each with a copy of the transaction history (ledger). Reaching consensus, or agreeing on the validity of new transactions and the current state of the ledger, prevents inconsistencies and maintains network integrity.

Popular Consensus Mechanisms

• Proof of Work (PoW)

Nodes compete to solve complex mathematical puzzles to earn the right to validate transactions and add new blocks to the chain. This process ensures security as altering the ledger would require immense computational power, but it can be energy-intensive.

• Proof of Stake (PoS)

Nodes validate transactions based on the amount of cryptocurrency they hold (their “stake”). This reduces energy consumption, but security might differ depending on the distribution of tokens. 

• Byzantine Fault Tolerance (BFT)

This theoretical concept ensures agreement even in the presence of faulty or malicious nodes. Many consensus mechanisms borrow principles from BFT to achieve consensus.

Reaching Agreement Through Votes

Some consensus mechanisms utilize a voting system. For instance, a majority of nodes (e.g., 51%) might need to agree on the validity of a transaction for it to be considered valid. This majority vote helps maintain the integrity of the network by preventing fraudulent activities.

The choice of consensus mechanism depends on the specific needs of a blockchain network, with factors like security, scalability, and energy consumption playing a key role. 

5. Application and Presentation Layers

The layered architecture of blockchain technology lays the foundation for a diverse ecosystem of applications. The Application Layer, sits atop the core infrastructure and unlocks the potential for innovation. Here’s what this layer offers:

• Building Decentralized Applications (dApps)

The application layer empowers developers to create dApps. Unlike traditional applications, dApps operate on a decentralized network, eliminating the need for central control. This fosters transparency, security, and resistance to censorship.

• Smart Contracts 

Smart contracts define the terms of a transaction and automatically execute upon fulfillment of predefined conditions. This eliminates the need for intermediaries, streamlines processes, and reduces costs in various domains like finance, supply chain management, and escrow services.

• Diverse Functionality Across Industries

The application layer opens doors to a wide range of possibilities across industries:

• Decentralized Finance (DeFi)

Enables peer-to-peer financial services like lending, borrowing, and trading without relying on traditional financial institutions.

• Supply Chain Management

Tracks the movement of goods with transparency and immutability, enhancing trust and efficiency.

• Identity Management

Enables secure and self-sovereign identity management solutions, empowering individuals to control their data.

• Voting Systems

Offers tamper-proof and transparent voting mechanisms.

• Developer Tools and Frameworks

The application layer provides developers with various tools and frameworks to build dApps. These tools simplify development processes and enable them to leverage blockchain functionalities seamlessly. Popular examples include Solidity (Ethereum), Hyperledger Fabric SDK, and Tendermint Core.

The Blockchain Layers Explained 

Layer 0

The foundation layer, or layer 0, serves as the basis for all other layers. The internet, hardware, and numerous more connections are needed for blockchain to function. The layer 0 powers multiple networks, including Ethereum, Bitcoin, and many more. Blockchain is additionally equipped with Layer 0’s cross-chain interoperability communication capability from top to lower layers. 

Examples of Layer 0 are Cosmos, Avalanche, and Polkadot.

Layer 1 (L1)

The majority of responsibilities that keep a blockchain network functioning, such as consensus-building, programming languages, protocols, and limitations, are under Layer 1. In this layer, the blockchain itself is represented. Scalability issues are sometimes brought on by the big number of jobs that this tier has to oversee.

The computational power needed to solve and add blocks to a blockchain increases with the number of participants, leading to higher fees and longer processing times. Improved consensus strategies like PoS and the introduction of sharding help to some extent to alleviate the scalability challenge.

Sharding is a technique for splitting a blockchain into smaller, more manageable sections called shards. This enables the processing of several transactions at once, increasing transaction speed and lowering costs. Examples of L1 include Ethereum, Binance Smart Chain, Bitcoin, and Solana.

Layer 2 (L2)

The blockchain needs more processing power to function efficiently. But doing so requires adding nodes, which chokes the network. Although adding nodes helps in maintaining a blockchain’s decentralized nature, experimenting with scalability, decentralization, or throughput impacts L1.

Layer 2 oversees all transactional validations by redesigning the L1. It constantly exchanges information with it within the blockchain ecosystem. For instance, a L2 blockchain that has been implemented on the bitcoin blockchain is the Lightning Network. It enables faster and cheaper transactions by processing them off-chain, reducing the load on the main blockchain.

Layer 3 (L3)

The “application layer” is another term for Layer 3 blockchain. This layer’s primary responsibility is to host the decentralized apps (dApps) and numerous other protocols that make other apps possible.

Application and execution are the two main sub-layers of the blockchain protocol that are divided here. L3 intends to provide ease of use and simplicity while interacting with L1 and L2. Crypto exchanges like Pancake Swap and Uniswap, payment mechanisms like Tornado Cash are examples of L3.

Challenges and Future Trends in Blockchain Layer Development

Blockchain layer development faces several challenges and is poised to evolve with emerging trends to address these issues and enhance the overall efficiency and scalability of blockchain networks. Some of the challenges in blockchain layer development are:

1. Scalability

One of the primary challenges is scalability, especially at L1. As blockchain networks grow, transaction throughput becomes a bottleneck. L1 solutions like PoW and PoS face limitations in handling increasing transaction volumes efficiently.

2. Interoperability 

Achieving interoperability between different blockchain networks and protocols remains a significant challenge. Seamless communication and data transfer between disparate systems require standardized protocols and robust cross-chain solutions.

3. Security and Privacy 

L1 must ensure robust security without compromising decentralization. Improving privacy features while maintaining transparency poses a challenge, particularly in public blockchains.

4. Energy Consumption 

PoW-based L1 blockchains consume substantial energy, raising concerns about environmental sustainability. Transitioning to more energy-efficient consensus mechanisms is imperative.

Future Trends in blockchain layer development are:

1. L2 Scaling Solutions 

Future developments will focus on implementing L2 scaling solutions like state channels, sidechains, and off-chain computations to relieve congestion on L1 and improve transaction throughput.

2. Cross-Chain Interoperability 

Enhanced cross-chain communication protocols and interoperability standards will enable seamless asset transfer and data exchange between different blockchain networks.

3. Privacy-Enhancing Technologies 

Integration of privacy-enhancing technologies like zero-knowledge proofs (ZKPs) and secure multiparty computation (MPC) at L1 will improve data confidentiality without compromising transparency.

4. Ecosystem Collaboration 

Collaborative efforts among blockchain projects and industry stakeholders will drive innovation in layer development, fostering standardized protocols and interoperable solutions.

Harnessing the power of blockchain layers requires collaborative efforts from developers, researchers, businesses, and policymakers. By embracing layered architectures and exploring their potential applications, we can unlock the full capabilities of blockchain technology, paving the way for a more inclusive, transparent, and resilient digital economy.