Explain PAXOS consensus Algorithm for Private Blockchain.

Key Points:

• Introduced by Leslie Lamport in 1989.

• Solves the consensus problem in asynchronous distributed systems.

• Ensures all nodes agree on a single value despite network issues or node failures.

• Operates in three phases: Prepare, Promise, and Accept.

• Three roles: Proposer, Acceptor, and Learner (optional).

Paxos Phases:

• Prepare Phase: Proposer sends “prepare” message with unique proposal number.

• Promise Phase: Acceptors respond with “promise” message, indicating no lower-numbered proposals.

• Accept Phase: Proposer sends “accept” message with proposed value; Acceptors validate.

Roles:

• Proposer: Initiates consensus process.

• Acceptor: Validates proposals.

• Learner: Observes consensus process (optional).

Benefits:

• Fault tolerance.

• Scalability.

• Flexibility.

Variations:

• Basic Paxos.

• Fast Paxos.

• Generalized Paxos.

Use Cases:

• Distributed databases.

• Private blockchain networks.

• Financial institutions.