As the Cardano ecosystem continues to grow and evolve, contributors to the Cardano ecosystem are committed to continually refining and optimizing Cardano's networking infrastructure. The release of Dynamic peer-to-peer (P2P) networking, delivered with node v.1.35.6, was a collaborative effort of the networking team from [IOG], [Well-Typed], [PNSol] and the [Cardano Foundation] and represents a highly performant deliverable and a significant milestone in Cardano's journey toward establishing a fully decentralized and secure blockchain platform.
Given that Cardano functions as a real-time stochastic system, its performance and security are inherently interconnected. The networking team remains committed to finding the ideal balance among various factors, including topological and topographic considerations, to enhance timeliness and connectivity.
This blog post takes you through the engineering journey behind the development of Cardano's Dynamic P2P design. It delves into the core design principles, highlights the challenges encountered along the way, and unveils the solutions the team devised to establish a robust and scalable networking system.
What is Dynamic P2P
The Dynamic P2P implementation continuously and dynamically refines the active topology through a peer selection process, with the objective of reducing the overall diffusion time across the entire network. Research findings suggest that utilizing a policy based solely on local information can result in an almost-optimal global outcome. This is achieved by monitoring the timeliness and frequency of peers that provide a block header, which is ultimately incorporated into the chain.
The primary goal is to eliminate highly ‘non-optimal’ peers while maintaining strong connectivity. To achieve this, peers considered less useful based on this metric are periodically ‘churned out’ and replaced with randomly selected alternatives. Simulation results indicate that this optimization method converges towards a near-optimal global outcome within a relatively small number of iterations.
Practically, Dynamic P2P replaces the manual configuration of peer selection (e.g. using the topology updater tool).
With manual configuration, stake pool operators (SPOs) were required to establish connections with a significant number of peers (50 for example) to maintain a minimum of 20 active connections consistently. This approach was necessary due to the static nature of configured peers and the varying availability of SPO relays.
However, with Dynamic P2P, nodes can be configured to maintain a specific number of active peer connections (e.g. 20) and select from all registered SPO relays on the chain. In the event of a lost connection with a peer, the node will automatically select alternative peers and persistently attempt connections until the desired target is reached.
As a result, Dynamic P2P eliminates the requirement for over-provisioning of connections, offering a more efficient and adaptable networking solution.