We have already covered how BSC transactions are propagated via the Mempool (Part I) and how MEV blocks are generated through the PBS bidding mechanism (Part II). Now, we look at the final step: How is this finalized block broadcast to the entire network?

On Solana, you are accustomed to the Turbine protocol—a UDP-based mechanism that "shreds" the block and efficiently broadcasts it through a stake-weighted tree structure with $O(\log n)$ latency.

BSC is completely different. It adopts a mechanism closer to traditional EVM chains: the TCP Gossip protocol, which broadcasts the complete block.

1. BSC Block Broadcast Mechanism Deep Dive (Full Block Gossip)

When a Validator (Proposer) finalizes a block, it immediately begins broadcasting. This process primarily relies on the TCP Gossip protocol.

1. Prepare and Seal: The Validator performs final calculations on the block (such as sealing the hash), appends its BLS signature, and writes the block to its local node.
2. Selective Full Block Broadcast (Propagate Block): The Validator does not immediately broadcast the full block to all Peers.
   • It selects a subset (typically $\sqrt{N}$ Peers) and sends the complete, RLP-encoded block body via TCP (the BlockAnnouncement message).
3. Hash Announcement Broadcast (Announce Hash): For the remaining Peers in the network, the Validator only sends the block hash (the BlockHashAnnouncement message).
   • This is a bandwidth optimization strategy designed to prevent network congestion.
4. Peers Receive and Chained Forwarding:
   • Peers receiving the full block: They immediately validate it. If valid, they repeat steps 2 and 3, forwarding the block (or just the hash) to their own Peers.
   • Peers receiving only the hash: If they don't have the block, they send a request to the sender to pull the complete block.
5. Voting and Finality: Other active Validators in the network, after receiving and validating the block, generate their BLS signature vote (broadcastVote) and propagate these votes via the Gossip protocol.
   • When a block receives 2/3 of the Validator votes (Justification), it is near final confirmation. Once its child block is also Justified, the block is considered Finalized (irreversible).

2. Comparison with the Solana Turbine Mechanism

3. Core Insights for Solana Traders: Fundamental Signal Source Differences

These two fundamentally different broadcast mechanisms result in completely different state update mechanisms and signal sources for traders.

In Solana: Your state update heavily relies on Shreds.

• You update the world state by pre-executing Shreds, subscribing to transactions via the geyser plugin, or using tools to deshred to get the raw transaction.
• Since there is no public Mempool, Shreds serve as both the "block broadcast" and the earliest "transaction signal" you can get. Your competitive edge comes from how quickly you can parse the Shreds.

In BSC: Your signal source is two-fold; you must monitor two critical signals simultaneously:

• Pending Signal ("What is about to happen?"):
  • Source: Public Mempool (NewPooledTransactionHashes broadcast).
  • Significance: This is the signal before the block is confirmed. Quickly acquiring these pending transactions is the foundation for building your trading strategy.
• Confirmation Signal ("What has already happened?"):
  • Source: Block Broadcast (BlockAnnouncement broadcast).
  • Significance: This is the confirmation of the final state. When you receive the complete block, you are 100% certain of the transaction results and can immediately trigger your next action (e.g., preparing for the next block competition).

4. Summary: BSC's Dual Race

For developers accustomed to Solana's "single Shred signal source," the strategy on BSC is dual:

• Race 1 (Mempool): You need the lowest latency access to the P2P network to capture pending transactions before others.
• Race 2 (Blocks): You need the most direct network connection to Validators to receive confirmed blocks before others.

On BSC, if your Mempool signal is slower than your opponent's, you cannot construct the optimal Bundle; if your block confirmation signal is slower, you lose the first-mover advantage in the next block's competition. This is why professional network services like BlockRazor, which provide high-speed P2P transaction and block broadcasting, are crucial in the BSC ecosystem.

This article series will continue to provide mechanism analysis, development suggestions, and the latest hot topics for BSC developers. We sincerely welcome you to join our Discord channel to discuss related topics and help you quickly familiarize yourself with the BSC platform.