FIL Fast Finality(F3) Mainnet is about to launch

Original author: FIL Network

FIL Fast Finality (FIP 0086: F3 in FIL) is one of the most revolutionary upgrades to the FIL consensus layer since the Mainnet launch. After nearly two years of intensive development, F3 is now ready for Mainnet deployment, promising groundbreaking progress for the entire ecosystem! By shortening the finality time from around 900 Block Height to just around 2, F3 brings comprehensive and substantial benefits:

• Faster transaction confirmation: Tokenholder and Dapp users will see the transaction completed in minutes, not hours.
• Enhanced Cross-Chain Interaction Experience: Oracle and bridge will complete transactions and state changes faster. Imagine a future Dapp that can seamlessly publish storage transactions from other chains to FIL and receive confirmation within minutes of the data being successfully stored in FIL!
• More efficient lightweight user end: RPC providers and storage providers, as well as node operators, can use lightweight user ends to improve accessibility.
• Simplified storage provider data storage process: F3 simplifies the data storage process for storage providers without the need for additional hardware or operational changes. Storage providers using SP user clients such as Lotus Miner, Venus, or Curio, or participating in the Ramo network, can significantly improve data storage efficiency. With F3, the storage transaction time is shortened by more than 2 minutes, allowing storage providers to achieve faster data storage processes and optimize SLA performance for users.
• And more benefits!

Changing the Consensus protocol of the real-time network is not easy. In order to smoothly and safely transition to the Mainnet, this change has undergone strict review and multiple rounds of testing in the calibrated network. Although F3 was initially designed for the nv24 upgrade, two key issues were later discovered in the experiments. Please check here for details. These issues have now been resolved, and the repair process is being verified in the calibrated network.

Next Step

The F3 team is now conducting final-stage preparation tests on the Mainnet. This includes deploying the updated protocol under production traffic and following the launch test plan. To provide more visibility, we have also released two F3 monitoring dashboards (Mainnet and Calibration Testnet) for the community to track progress, monitor block finality, Node performance, etc. If you want to get the latest test updates, please subscribe to this forum or join the #fil-fast-finality slack channel.

Node Operator Notes

When we enter the final passive testing phase on the Mainnet, it is important to understand the bandwidth usage pattern of F3. These patterns are mainly driven by two key factors:

• Message Volume: F3 requires the opinions of at least 66% of the network power participants to make decisions.
• Message size: The more blocks in the Block set that need to be processed, the larger the message.

👋🔔Expected Bandwidth Usage During Bootstrap

During the bootstrap stage, F3 must complete all block heights since the last termination, which is about 900. This termination of the extended chain will result in a temporary peak in bandwidth usage, usually lasting 5-10 minutes, and then stabilize to the baseline level.

Other Known High Bandwidth Scenarios

F3 achieves finality in the so-called "instances": you can think of instances as meetings where everyone attends to make decisions on certain matters. At least 66% of attendees are needed for the meeting to adjourn. After F3 bootstrap, each instance typically contains a few blocks of block heights during normal operation. This is because F3, as the name suggests, is fast finality, and in most cases, it can finalize blocks within 2 block heights.

However, in some cases, the final determination of F3 may lag behind the progress of the chain. For example, 'meetings' may take a long time to end due to lack of participation or network connection issues. As FIL chain continues to rise, instances that occur after long durations now require a longer chain to complete. A longer chain means there will be larger messages, as each message exchanged as part of the F3 instance contains information about the final completion of the chain. Larger messages will lead to a sharp increase in bandwidth usage, but once the F3 instance catches up with the speed of the chain and completes the Block set within the recent few Block Heights, the bandwidth usage will drop to the baseline.

If you find that the bandwidth usage related to F3 testing remains unexpectedly high for a long time, please collect logs from your deployment, especially from the F3/gpbft and F3/certexchange log levels, and share them in the #fil-fast-finality Slack channel. The F3 team will actively monitor the performance and work with you to investigate and resolve the issue.

🏁F3 Start

In the next 2-4 weeks, we will continue to collect data on the rationality of the implementation of F3 through passive testing. Our current plan is to launch F3 using nv25.

While we are waiting for the final data to confirm whether F3 is ready, the F3 team plans to propose an off-cycle upgrade to nv25 for FIL implementers and core developers. If there are no critical issues during the final stage of testing, we will make the following recommendations for the release of F3:

• Early December 2024 - release the calibrated nv25 upgrade and deploy the final code of F3 (F3 has been activated and is running)
• Mid-December 2024 - User-side release of Mainnet nv25/F3 activation Block Height set
• January 2025 - Mainnet nv25/F3 Activation

We will keep you updated on the progress at any time and provide updates to the community when there are any changes to the plan. Thank you for your strong support for this exciting upgrade!

You can follow FilOz's blog and Twitter for the latest updates on Finality unveiling.

Special thanks to other F3 core implementers: Kubuxu, Masih, Stebalien, annorth, BigLep; other Lotus implementers rvagg and Forest implementer Hailong and ruseinov, thank you for your hard work to bring F3 into real life.

More Resources

• FIL Foundation: How F3 Changes the FIL Network
• MasihDerkani: Fast, Final Deterministic: Simplified bridge to other networks
• Protocol Labs Research: F 3 and gossip pbft: rapid finality of the longest chain protocol
• Github
• Slack：# fil-fast-finality