Proof of Bandwidth Validation
Introduction
Imagine you’re selling Internet to your neighbor for $20 a month, promising gigabit speeds. How does your neighbor know that you actually have a gigabit to spare? And if they’re not getting the promised speed, what recourse do they have? This is where the importance of verifiable bandwidth comes into play in the DAWN protocol.
In this new Internet where households are contributing digital resources (storage, bandwidth, compute, etc.) to a decentralized network, one of the most important items to address is Quality of Service. How do buyers of supply on the network know that the supply is as advertised, without any central intermediary?
To address this challenge, various Proofs are designed to provide a trustless measure of the quality of the supply a user provides to the network. In the same way a blockchain provides trustless consensus at the data layer, new Proofs are required to provide trustless consensus at the infrastructure layer.
With DAWN as a protocol for decentralized broadband, the primary supply on the network is bandwidth. To provide a trust-free measure of bandwidth at any given point in the network, DAWN is using a novel approach by integrating Witness Chain’s Proof of Bandwidth (PoB), a mechanism designed to verify network performance in a decentralized and tamper-resistant manner. At its core, PoB acts as a decentralized speed test, aggregating observations from a distributed network of watchtowers to generate a Byzantine-resistant proof of bandwidth.
In this blog, we’ll explore why it’s important, how PoB works, its integration into DAWN, and how it strengthens the overall security and reliability of other DePINs.
Why this is important
In a decentralized network like DAWN, where users offer digital resources such as bandwidth, ensuring that the supply meets advertised standards is critical. Without a centralized authority to verify these claims, the protocol needs a mechanism to guarantee that the service provided is what was promised. Proof of Bandwidth (PoB) addresses this challenge by offering a trustless, decentralized method to verify network performance.
PoB works like a decentralized speed test, collecting data from a network of independent watchtowers to generate a proof that the bandwidth you’re selling is truly available and reliable. This verifiable supply doesn’t just provide transparency; it also enables programmatic recourse. If you’re not getting the gigabit speed your neighbor promised, the decentralized Service Level Agreement (SLA) implemented in smart contracts can automatically adjust payments or enforce penalties, ensuring fairness and trust in the transaction.
This mechanism is essential for building a reliable and trustworthy decentralized network. It ensures that users are confident in the quality of the services they purchase, and it holds providers accountable, making decentralized broadband a viable alternative to traditional ISPs. In this way, PoB is not just a technical feature; it’s the backbone of a system that empowers consumers and builds a fairer, more transparent digital economy.
As other DePIN projects emerge, the importance of robust and verifiable connectivity becomes increasingly critical. Connectivity is the backbone of any decentralized infrastructure network, ensuring that the data flows smoothly from local nodes to the broader internet. Without a reliable Internet connection, even the most advanced decentralized systems would struggle to deliver consistent performance. This is why DAWN’s integration of Proof of Bandwidth is so crucial—not just for its own network, but as a model for all future DePIN projects. By setting a standard for verifiable, high-quality backhaul, DAWN is paving the way for a new generation of decentralized networks that are capable of scaling globally while maintaining the transparency and reliability that users expect.
How it works
Proof of Bandwidth (PoB) in DAWN operates to prove the size of a node's bandwidth capacity through a decentralized verification process. To understand how this works, imagine you’re trying to prove the size of a bucket. You claim that your bucket can hold a certain amount of water, but how can others trust that claim? In this analogy, dozens of watchtower nodes offer their spare bandwidth, simultaneously flooding your bucket with water. The amount of water that stays in your bucket, without spilling over, can be proved with cryptographic signatures. Those signatures demonstrate the actual capacity of your bucket—or in DAWN's case, your bandwidth.
The watchtower nodes utilize UDP (User Datagram Protocol) to transmit data. Unlike TCP (Transmission Control Protocol), UDP avoids the issue of slow start, allowing for more accurate measurements in real-world scenarios. While TCP's fairness property enhances theoretical accuracy, it is less suitable for practical implementation.
The DAWN Chrome extension is a practical example of these watchtower nodes in action. Users who install the extension contribute their spare bandwidth to challenge other nodes in the DAWN network, effectively participating in a decentralized speed test. When a prover claims to have a certain amount of bandwidth, these watchtower nodes send bursts of data to validate the claim. The prover’s ability to handle the incoming data is measured, and a cryptographic proof is generated based on the results.
How it is integrated
DAWN integrates Proof of Bandwidth (PoB) directly into DAWN-compatible routers, ensuring that this verification process is an integral part of the network’s operation. These routers are designed to run PoB continuously, with challenges issued at random intervals to test and prove the bandwidth being offered. This ensures that the network remains trustworthy and that all bandwidth claims are accurate and verifiable.
To achieve the high performance required for multi-gigabit results, DAWN and WitnessChain have collaborated to create a software router using DPDK (Data Plane Development Kit) and VPP (Vector Packet Processing). This combination allows commodity hardware to act as a multi-gigabit router, delivering personal and neighborhood connectivity at a fraction of the cost of traditional high-end routers from companies like Juniper and Cisco.
Within this setup, Proof of Bandwidth runs as an application written in C that interfaces directly with VPP, receiving packets as they are processed by the router. This tight integration allows the PoB algorithm to execute efficiently, ensuring accurate and timely proofs without adding significant overhead to the network. With PoB embedded directly into an affordable, high-performance router, DAWN guarantees that the quality of service is maintained across the network -- from individual homes to broader neighborhood connectivity.
PoB is designed to be resilient, delivering verifiable results even when some watchtower nodes behave adversarially. To maintain the system's security, it is essential to deploy a large number of watchtower nodes. This is achieved through the extensive watchtower network maintained by Witness Chain. The security of this setup hinges on the principle that no adversary should be able to control a significant portion of the network's nodes.
The network consists of numerous nodes operating via DAWN's Chrome extension, further bolstered by additional nodes spread across various DePINs. This robust architecture is fortified by significant cryptoeconomic security, provided by Eigenlayer's operators, who execute PoB as part of Witness Chain's Actively Validated Service (AVS), ensuring the integrity and resilience of the system.
Wrapping Up
DAWN is one example of a protocol that furthers the DePIN vision – an Internet that is powered by you. In this future, with decentralized networks that harken back to the motivation of the Internet’s creators, the Internet will be transparent and user powered. Without any central authority, there is also an increased necessity for accountability. By leveraging smart contracts with Proof of Bandwidth, this network will form without trust, allowing the seamless exchange of bandwidth, with the goal of turning bandwidth into a proper commodity.
The technology required to realize this implementation are at the cutting edge of networking and decentralization, and we’re excited to share the open source implementation with the community over the next several months. Stay tuned.