Distributed Consensus in Distributed System

Distributed Consensus

Distributed consensus plays a vital role in decentralized systems, ensuring reliability, fault tolerance, and agreement among multiple parties. Distributed consensus occurs when multiple parties try to accept some values, which is difficult as agreeing is not easy. The complexity to achieve consensus increases as an increase in the number of parties agree on an agreement. Various sites are working together to do a common task by communicating with each other via a network and agreeing to some values which come under distributed consensus.

Importance of Distributed Consensus in Distributed Systems

In a distributed or decentralized multi−agent platform, reaching a common agreement is crucial for maintaining reliability and fault tolerance. When multiple individual parties are involved, each with the ability to make their own decisions, it becomes necessary to establish a common point of view. This is especially important in environments where malicious or faulty behavior can occur. The objective is to ensure correct operations even in the presence of faulty individuals.

The conditions to achieve distributed consensus are

Termination: All non−faulty nodes eventually decide which ensures that the consensus is reached by all parties involved.

Agreement: All non−faulty processes must agree on the same value which guarantees that all correct nodes in the network will come to a consensus.

Validity: Every non−faulty process should begin and end with the same value. This ensures that the agreed−upon value reflects the initial choice of some process.

Integrity: At least a single value should be decided by every individual, and then proposed by some individual. This prevents multiple conflicting decisions and ensures the integrity of the consensus.

Correctness of Distributed Consensus Protocol

Safety Property

The safety property ensures that correct individuals in a network will never converge to an incorrect value. It guarantees that the agreed−upon value is always correct.

Liveness Property

It asserts that every accurate value must finally be recognized, indicating that positive outcomes are expected.

Agreement Property

It ensures that all right procedures will ultimately concur on the same value. As a result, the network will always reach a consensus with all valid nodes.

Fault Tolerance

Distributed consensus techniques need to be able to withstand network and participant node failures and faults. This guarantees that even in the face of errors, the system will continue to be correct and functioning.

Termination Property

Every valid process will inevitably choose a value, according to the Termination Property. As a result, the procedure will finally terminate.

Byzantine Fault Tolerance

Byzantine Fault Tolerance (BFT) is an extra characteristic of several distributed consensus protocols, such as PBFT. This indicates that they can withstand a limited number of malicious nodes without sacrificing the network's security and liveliness qualities.


The protocol must be scalable to manage huge networks and a rising number of nodes without compromising fault tolerance, liveness, or safety. This guarantees that the procedure can be applied in situations involving many participants in the real world.

Applications of Distributed Consensus

Leader Election

In a fault−tolerant environment, distributed consensus can be used to elect a leader. This allows for the initiation of global actions without introducing a single point of failure.

Maintaining Consistency

Distributed consensus protocols can ensure consistency in a distributed network. For example, if multiple nodes are monitoring the same environment and one of the nodes crashes a consensus protocol can ensure robustness against such faults.

Blockchain Technology

Blockchain technology is based on the idea of distributed consensus which does not rely on a centralized authority and enables several nodes to agree on a shared database. Consensus protocols, such as Proof of Work (PoW) or Proof of Stake (PoS), ensure the integrity and security of the blockchain.

Distributed Databases

Consensus protocols can be used to maintain consistency across multiple replicas of a distributed database. This ensures that all replicas have the same information and that data integrity is maintained.

Load Balancing

In a distributed system, the consensus method can be used to dynamically spread the workload across several nodes. This guarantees that no node is overburdened and that the system runs smoothly.

Fault Tolerance

In distributed systems, fault tolerance is provided through distributed consensus mechanisms. They make sure that the system continues to function even amid errors by enabling nodes to recover from failures or network partitions.

Agreement Protocols

Multiple nodes in a distributed system can agree on a certain course of action or conclusion by using consensus methods. This is helpful in situations when synchronization and cooperation are necessary.


This article consists of Distributed consensus in distributed systems. distributed consensus plays a vital role in decentralized systems, ensuring reliability, fault tolerance, and agreement among multiple parties. Conditions to achieve distributed consensus are termination, agreement, validity, and integrity. Distributed consensus protocols enable correct operations even in the presence of malicious or faulty behavior. The properties are safety, liveness, agreement, fault tolerance, termination, BFT, and scalability. Applications are leader election, Maintaining Consistency, Blockchain Technology, Distributed Databases, Load Balancing, Fault Tolerance, and Agreement Protocols.

Updated on: 14-Jul-2023


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