Alpenglow: Solana's Largest Protocol Upgrade Ever | Brennan Watt, Anza

Introducing Alpenglow: Solana's Most Consequential Upgrade

Solana, the high-performance blockchain known for its speed and efficiency, is on the brink of a major evolution. Alpenglow, described as Solana's largest protocol upgrade ever, promises to revolutionize the network's performance and security. In this in-depth exploration, we dive into the details of Alpenglow, its potential impact, and the future of Solana with Brennan Watt, VP of Core Engineering at Anza.

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What is Anza?

Anza is the company behind Solana's core development. Spun out from Solana Labs a year and a half ago, Anza comprises the entire core dev protocol team. Their mission is clear: to make the Solana base layer scale with high performance, incredible liveness, and all the properties desired in a solid Layer 1 blockchain. Anza is best known for developing the Agave client, the software that powers the vast majority of Solana's network.

Alpenglow: A Leap Forward in Transaction Finality

The headline feature of Alpenglow is its potential to reduce Solana's transaction finality time by a factor of 100. But what does this mean in practice? Currently, Solana uses a system called Tower BFT, which has a finality time of 12.8 seconds. This is the time it takes for a transaction to be irrevocably confirmed on the network. While Solana introduced optimistic confirmation to improve user experience, Alpenglow aims to dramatically reduce the actual finality time to around 100 milliseconds.

Brennan Watt explains: "With Alpenglow, one of the big differences is that we actually wait for these certifications before considering a fork valid. Currently with Tower BFT, you're just building blocks, validators are observing votes, but they're kind of independently making their decision like, 'Hey, I think this is the best fork to build on.' With Alpenglow, we have more of these hard cuts where we'll optimistically pipeline things, but we're waiting for that hard certification."

The Technical Underpinnings of Alpenglow

Alpenglow introduces several key changes to Solana's architecture:

1. Out-of-band Finality: Unlike the current system where votes are included as transactions in blocks, Alpenglow moves voting out-of-band. This decouples finality from Solana's slot times, making it more a function of network latency.

2. Simplified Fork Selection: By waiting for certifications before considering a fork valid, Alpenglow drastically simplifies fork selection. This makes the decision more binary - is this block good or not?

3. Removal of Proof of History: Alpenglow replaces Solana's unique Proof of History mechanism with a simpler system based on local clocks and skip votes.

4. Changes to Fault Tolerance: Alpenglow makes trade-offs in fault tolerance, requiring resilience to 20% malicious actors and an additional 20% of the network being offline.

How Solana Works Today

To understand the significance of Alpenglow, it's crucial to grasp how Solana currently operates. Solana uses a leader-based system where one validator at a time is responsible for building and broadcasting blocks. These blocks are cut into "shreds" or "slices" and broadcast using a statistical algorithm called erasure coding.

Brennan elaborates: "We need every node to observe every block. That's really critical. But you also don't want to have an insane amount of overhead when you're getting those blocks out. So we have to balance all of these concerns."

The current system uses a mechanism called Tower BFT for consensus, which builds up a "tower" of confirmed blocks. When this tower reaches a certain height, the bottom blocks are considered finalized. This system, while functional, has limitations in terms of finality time and mathematical provability.

Alpenglow's Impact on Network Security

One of the key benefits of Alpenglow is its potential to enhance network security. By simplifying the fork selection process and introducing hard certifications, Alpenglow makes it more difficult for malicious actors to manipulate the network.

Watt explains: "If we do this right, we can still pipeline things very efficiently, but we also have that confidence. And so you don't really see forking in Alpenglow. It drastically simplifies the fork selection because it's really just, 'Hey, is this block good or not?' It's kind of a binary."

Liveness on Solana

Liveness, or the ability of the network to continue processing transactions without interruption, has been a focus for Solana following past outages. Alpenglow aims to improve liveness by simplifying the consensus mechanism and reducing the chances of network halts due to conflicting forks.

Brennan emphasizes the progress made: "We've had well over a hundred billion transactions since our last liveness issue. When you talk about successful state-altering non-vote transactions, it's still like 10 billion or something like that since our last liveness issue."

Doubling Blockspace: A Parallel Effort

While Alpenglow focuses on improving finality and consensus, Anza is simultaneously working on doubling Solana's blockspace. This effort involves optimizing how block data is relayed to validators, moving from a kernel syscall method to a more efficient XDP (eXpress Data Path) approach.

Watt explains: "The biggest thing is changing the retransmit, which is how we kind of relay the block data out to the validator network. So going from more of a kernel syscall method to more of an XDP, so user space, it's fewer copies of data, much faster way of computationally getting that data out."

Alpenglow's Impact on Solana's Economics

The introduction of Alpenglow has significant implications for Solana's economic model. By moving votes out-of-band, it reduces the operational costs for validators, particularly benefiting smaller validators who currently spend around one SOL per day on voting costs.

However, this change also necessitates new economic incentives. Brennan notes: "We need some way of observing it, some way of incentivizing it and doing some payouts. But I'm not sure exactly what that's going to look like in the end."

The Incentive to Run a Solana Relayer

Relayers play a crucial role in Solana's network by helping distribute block data. Currently, there are economic incentives for running relayers, primarily driven by the value of having fresh, low-latency data for trading and other time-sensitive applications.

Watt explains: "If I'm a trader, any sort of latency edge I can get in understanding the state of the chain is invaluable. And so we don't have to really do anything in protocol to incentivize those pieces."

Reducing Malicious MEV

Miner (or Maximal) Extractable Value (MEV) is a concern in many blockchain networks, including Solana. Alpenglow, combined with other planned upgrades, aims to reduce the potential for malicious MEV by introducing multiple concurrent leaders and creating a more competitive, anti-censorship dynamic.

Brennan outlines the vision: "If we create more of a marketplace there, then it becomes a lot harder to censor because now I may be able to kind of manipulate things in some way that helps me by censoring a transaction, but I'm at the mercy of the other two leaders also."

Alpenglow's Launch Timeline

The Anza team is working aggressively to bring Alpenglow to mainnet. While the official timeline targets early 2026, Brennan hints at the possibility of an earlier launch: "We would love to be standing on the stage in Abu Dhabi at Breakpoint and talking about how it's doing on mainnet."

MEV on Solana

MEV, or the value that can be extracted from transaction ordering, remains a topic of discussion in the Solana ecosystem. Alpenglow, with its faster finality and potential for multiple concurrent leaders, could significantly impact MEV dynamics on Solana.

Watt emphasizes the approach: "We think IBRL (Increased Block Rate Limit) is kind of the easiest thing for us to put the blinders on and focus on when it comes to helping with some of these economic issues."

Competing With the Firedancer Team

The development of Alpenglow has implications for Firedancer, another client implementation for Solana. While there's a spirit of competition, there's also collaboration between the teams.

Brennan notes: "We're competitive, but we're friendly and we learn from each other all the time. And the simplicity of Alpenglow probably makes Firedancer's job a bit easier."

How Solana Remains Competitive

In the face of increasing competition in the blockchain space, Solana continues to innovate. Alpenglow is just one part of a broader strategy to maintain Solana's edge in performance and user experience.

Watt emphasizes this approach: "We recognize some of the threats that are coming in and people may be picking a different point on the performance decentralization curve and trying to come after that experience. And that's why we stay paranoid and we're working on a ton of stuff to make the chain even faster, even more decentralized."

Rolling Out Network Upgrades

The process of rolling out major upgrades like Alpenglow involves careful consideration and multiple stages of governance. Brennan outlines three main buckets:

1. Low friction improvements to the client implementation
2. Protocol-level changes requiring consensus among different client teams (using the SIMD process)
3. Economic changes requiring a governance vote from validators

Alpenglow falls into the second and potentially the third category, highlighting the complexity of implementing such a significant upgrade.

Anza's Future Work

Beyond Alpenglow, Anza is working on several other improvements to the Solana protocol. These include:

1. Reducing slot times, potentially to 200 milliseconds
2. Increasing efficiency in network communication
3. Opening up the scheduler for more customization by validators
4. Continuing to optimize block space and transaction throughput

Brennan hints at the potential impact: "I think this one's flying hugely under the radar. And all of a sudden people are going to wake up and realize, 'Oh my gosh, this is giant,' like probably on the same level as an Alpenglow."

The Importance of Real-World Testing

One of Solana's strengths has been its ability to handle high transaction volumes in real-world conditions. Brennan emphasizes the value of this experience: "You just can't replicate a Trump coin launch in a lab environment and be ready for that. You need to test on your actual systems with the actual geographic distribution and all that kind of stuff."

Addressing Common Misconceptions

Brennan takes a moment to address some common misconceptions about Solana, particularly around performance metrics and comparisons with other blockchains. He emphasizes the importance of context when discussing metrics like transactions per second (TPS) and the need to consider the actual work being done during uptime, not just the passage of time.

The Role of Research in Solana's Development

The development of Alpenglow highlights the increasing role of academic research in Solana's evolution. The upgrade was conceived by a team from ETH Zurich (not to be confused with Ethereum) who initially published a paper critiquing Solana's existing consensus mechanism.

Watt explains the value of this collaboration: "It's been awesome having them on board. I mean, it's a bunch of big brains that understand blockchain extremely well and not just kind of getting something that kind of works, but really provably correct."

Balancing Innovation and Stability

As Solana continues to evolve, there's a delicate balance to strike between rapid innovation and maintaining network stability. Brennan emphasizes the importance of this balance: "If we were not concerned about liveness issues and maintaining a healthy amount of paranoia, I don't think we'd be doing our jobs as core devs very well. But the flip side of that is we absolutely don't want to ossify the protocol and use that paranoia as fuel for being scared of making good changes."

The Future of Solana's Consensus Mechanism

Alpenglow represents a significant shift in Solana's consensus mechanism, moving away from the unique Proof of History approach that has been a hallmark of the network. This change demonstrates Solana's commitment to evolving based on new research and real-world performance data.

Watt explains: "We're not scared. We like to iterate. We'll learn. But also we're not sloppy with a lot of these changes. And so yeah, I think you're experiencing some of that now where it's been well over a year. Liveness has gotten a lot better."

Implications for Developers and Users

While much of the discussion around Alpenglow focuses on technical and economic aspects, it's important to consider the implications for developers and users of the Solana network. Faster finality and improved liveness could enable new types of applications and improve user experiences across the ecosystem.

Brennan hints at the possibilities: "Opening the door to people being able to do intelligent things with the scheduler without having to full-on fork the Agave clients. We want to allow some of those hooks for creative smart cracked engineers to do fun things to go maximize their block rewards and a lot of other cool things."

The Road Ahead for Solana

As Solana prepares for the implementation of Alpenglow and other upgrades, the future looks bright for the high-performance blockchain. With a focus on continuous improvement, real-world testing, and a willingness to challenge even fundamental aspects of the protocol, Solana is positioning itself to remain at the forefront of blockchain technology.

Watt concludes with an optimistic outlook: "We've got a lot of development ahead of us. It's also a big reason why we're being so aggressive with the timelines and pushing this as we know we have some of these big dependent features that we need to get in."

As the blockchain space continues to evolve, Solana's Alpenglow upgrade stands as a testament to the network's commitment to innovation, performance, and security. With its potential to dramatically improve transaction finality and overall network efficiency, Alpenglow could mark a new chapter in Solana's journey to become the world's most performant blockchain.

Facts + Figures

• Alpenglow aims to reduce Solana's transaction finality time from 12.8 seconds to around 100 milliseconds, a 100x improvement.
• Solana has processed over 100 billion transactions since its last liveness issue, including about 10 billion successful state-altering non-vote transactions.
• Anza, the company behind Solana's core development, was spun out from Solana Labs a year and a half ago.
• The Alpenglow upgrade was conceived by a research team from ETH Zurich, initially known for publishing a paper critiquing Solana's existing consensus mechanism.
• Alpenglow makes trade-offs in fault tolerance, requiring resilience to 20% malicious actors and an additional 20% of the network being offline.
• Anza is working on doubling Solana's blockspace by optimizing how block data is relayed to validators.
• Current Solana validators spend around one SOL per day on voting costs, which Alpenglow aims to reduce by moving votes out-of-band.
• The official timeline for Alpenglow's launch targets early 2026, but the team is working towards a potential earlier launch, possibly by the end of 2025.
• Anza is aiming to reduce Solana's slot times from 400 milliseconds to potentially 200 milliseconds in the future.
• The Anza team has already reduced gossip traffic by 25% with the recent 2.2 rollout.
• Solana's development process involves three levels of changes: low-friction client improvements, protocol-level changes requiring consensus (SIMD process), and economic changes requiring validator votes.
• Alpenglow replaces Solana's unique Proof of History mechanism with a simpler system based on local clocks and skip votes.
• Anza is working on opening up the scheduler for more customization by validators, potentially allowing for application-specific sequencing and other innovations.

Questions Answered

What is Alpenglow?

Alpenglow is Solana's largest protocol upgrade to date, aimed at dramatically improving transaction finality and overall network performance. It introduces a new consensus mechanism that could reduce finality time from 12.8 seconds to around 100 milliseconds, a 100x improvement. Alpenglow also simplifies fork selection, moves voting out-of-band, and replaces the Proof of History mechanism with a more efficient system.

How does Alpenglow improve Solana's performance?

Alpenglow improves Solana's performance in several ways. First, it reduces transaction finality time to around 100 milliseconds, allowing for faster confirmation of transactions. It also simplifies the fork selection process, making the network more resilient to potential attacks. By moving votes out-of-band, Alpenglow reduces the overhead on the network, potentially allowing for shorter slot times and increased transaction throughput in the future.

What changes does Alpenglow make to Solana's consensus mechanism?

Alpenglow introduces significant changes to Solana's consensus mechanism. It replaces the current Tower BFT system with a new approach that uses out-of-band voting and hard certifications for blocks. The upgrade also removes the Proof of History mechanism, replacing it with a system based on local clocks and skip votes. These changes simplify the consensus process while maintaining security and improving finality times.

How does Alpenglow affect Solana's economics?

Alpenglow has several implications for Solana's economics. By moving votes out-of-band, it reduces operational costs for validators, particularly benefiting smaller validators. However, this change also necessitates new economic incentives for activities like relaying block data. The exact details of these new economic models are still being worked out, but they aim to maintain a healthy and decentralized network while improving overall performance.

When will Alpenglow be implemented on Solana's mainnet?

The official timeline for Alpenglow's launch targets early 2026. However, the Anza team is working aggressively towards a potential earlier launch. They hope to potentially showcase Alpenglow running on mainnet at the Breakpoint conference in Abu Dhabi at the end of 2025. The exact launch date will depend on thorough testing and the readiness of all components of the upgrade.

How does Alpenglow impact MEV (Maximal Extractable Value) on Solana?

Alpenglow, combined with other planned upgrades like multiple concurrent leaders, could significantly impact MEV dynamics on Solana. By creating a more competitive environment for transaction inclusion and reducing the window for potential manipulation, Alpenglow aims to reduce the potential for malicious MEV. The faster finality times could also change the landscape for MEV extraction, potentially making some current strategies less viable.

What other improvements is Anza working on for Solana?

In addition to Alpenglow, Anza is working on several other improvements to the Solana protocol. These include doubling the blockspace, reducing slot times to potentially 200 milliseconds, increasing efficiency in network communication, and opening up the scheduler for more customization by validators. They are also continuously working on optimizing various aspects of the protocol to improve performance and scalability.

How does Alpenglow compare to upgrades in other blockchain networks?

While it's difficult to make direct comparisons due to the unique architectures of different blockchains, Alpenglow represents a significant leap in performance for Solana. The potential 100x improvement in finality time is particularly notable. Unlike some other blockchain upgrades that focus on incremental improvements, Alpenglow represents a fundamental shift in Solana's consensus mechanism, demonstrating the network's commitment to evolving based on new research and real-world performance data.