RAFT in Blockchain Technology 🔥🔥

Summary

This tutorial explains the RAFT consensus protocol used in blockchain networks, focusing on its key components: leader and follower nodes. The leader issues commands, and the followers follow these commands based on a unanimous decision-making process. The video walks through how leaders are elected, how requests are made, and the conditions for accepting or rejecting changes in the network. It also covers edge cases such as leader or follower failures, and how to handle ties in leader election. The protocol ensures consistency and fault tolerance in decentralized systems, making it an essential concept for blockchain technology.

Takeaways

• 😀 Consensus refers to unanimous decision-making where all nodes in a blockchain network must agree on a change, whether it's positive or negative.
• 😀 RAFT algorithm divides nodes into two categories: Leader (who gives orders) and Followers (who follow the leader's orders).
• 😀 Leader election is done by followers voting for candidate leaders, and the candidate with the most votes becomes the leader.
• 😀 The leader sends a request to all followers to implement a change in the network, including parameters like 'Term' (round number) and 'Index' (transaction number).
• 😀 A request is only accepted if its 'Term' is greater than or equal to the current 'Term' of the node, ensuring that older requests are not processed.
• 😀 Similarly, the 'Index' of the request must be equal to or greater than the follower's current transaction index for the request to be accepted.
• 😀 If a leader fails, a new leader is elected based on the highest term number, and the process continues without issue.
• 😀 If a follower fails, as long as more than 50% of the followers are active, the network can still reach unanimous decisions.
• 😀 If multiple candidates receive the same number of votes in a leader election, a new round of voting is triggered to determine the leader.
• 😀 The new leader's 'Term' must be greater than the previous leader’s term to ensure that the old leader acknowledges the change and follows the new leader.
• 😀 The process of RAFT ensures that all nodes stay in sync and maintain network integrity, even when some nodes fail or become inactive.

Q & A

What is the meaning of 'consensus' in the context of blockchain?

Consensus in blockchain refers to a unanimous decision made by all nodes (participants) in the network. This means that every node agrees on a particular action or change, ensuring consistency and avoiding conflicts in the network.

How is a leader elected in the RAFT consensus algorithm?

In the RAFT algorithm, followers vote for a candidate to become the leader. The candidate who receives the most votes becomes the leader, and all other nodes follow the leader's orders.

What are the two key parameters in the leader's request to followers?

The two key parameters in the leader's request to followers are 'Term' and 'Index'. 'Term' indicates the round number of the request, while 'Index' reflects how many transactions have taken place so far in the blockchain network.

What happens if the leader fails during the RAFT consensus process?

If the leader fails, the system can elect a new leader. This ensures that the network continues functioning without disruption, as long as there are enough active followers.

How does RAFT handle the failure of a follower node?

The failure of a follower node does not affect the consensus process as long as more than 50% of the followers remain active. If too many followers fail, the system will be unable to reach consensus.

Why is it important that the leader’s term number should always be higher than the previous leader's term?

The leader’s term number must be higher to prevent outdated or failed leaders from regaining control. A higher term number ensures that the current leader is recognized as the active and legitimate one, keeping the consensus process intact.

What happens if a follower receives a request with a lower term number than its current term?

If a follower receives a request with a term number lower than its current term, it will decline the request. This ensures that older or outdated requests do not override more recent and valid decisions.

In the event of a tie in the voting process, how is the new leader selected?

In the case of a tie, the voting process is restarted. New votes are cast, and the candidate with the most votes in the new round becomes the leader, while others become followers.

What does the term 'Index' represent in the RAFT protocol?

The 'Index' represents the number of transactions that have been processed up to that point in the blockchain. It helps track the progression of the system and ensures that requests and changes are applied in the correct sequence.

How does RAFT ensure consistency in a decentralized blockchain network?

RAFT ensures consistency by requiring unanimous decision-making among all nodes. Through the leader-follower structure and the use of terms and indices, RAFT ensures that all changes in the network are agreed upon by the majority before being implemented.