6 posts tagged with "simulation-analysis"

This week marked a significant milestone with the formal publication of the Ouroboros Leios CIP proposal, complemented by the release of the second comprehensive technical report and extensive network performance analysis. The team successfully delivered the definitive protocol specification and supporting evidence to the Cardano Foundation for formal review.

Major milestone achievement​

CIP proposal publication​

The team published the Ouroboros Leios CIP proposal to the Cardano Foundation CIPs repository, representing the culmination of extensive research, analysis, and specification development. The proposal has been submitted for formal review and is pending assignment of a CIP number at the next CIP meeting. This submission provides the definitive technical specification for the proposed Leios protocol implementation, establishing the foundation for community review and potential integration into the Cardano ecosystem.

Second technical report release​

The team completed and released the second technical report, capturing comprehensive modeling, simulation, and analysis findings from March to August 2025. This substantial document covers network protocols, threat model analysis, simulation experiments, test network topologies, empirical Cardano network measurements, analytic studies of proposed Leios behavior and performance, and extensive technical observations. The report provides provisional findings and conclusions acknowledging the evolving nature of the protocol design during the study period.

Network infrastructure analysis​

Inter-datacenter bandwidth measurements​

The team conducted extensive inter-datacenter bandwidth measurements using iperf3 for bidirectional testing between locations across North America and Europe. The comprehensive analysis examined bandwidth between OVH, AWS, and CenturyLink infrastructure across multiple geographic regions, establishing empirical baselines for network performance expectations in distributed deployment scenarios.

Key findings from the bandwidth analysis indicate that 100 Mbps represents a conservative lower bound for inter-datacenter connectivity, with significant variation based on geographic distance and infrastructure provider combinations. The measurements revealed bandwidth ranges from 95 Mbps (CenturyLink Colorado to OVH Canada) to 973 Mbps (AWS Oregon to OVH Oregon), providing critical input for proposed Leios deployment planning and parameter optimization.

Network degradation resilience analysis​

The team completed comprehensive network degradation experiments, examining proposed Leios behavior under severely constrained network topologies. The analysis systematically reduced network connections by up to 87% from original mainnet-like topology configurations, testing protocol resilience under extreme network degradation scenarios.

The degradation experiments demonstrated that the proposed Leios protocol continues to operate correctly even when 87% of network connections are lost, with the network diameter increasing from 5 to 8 hops and the average connections per node dropping from 23.5 to 6.0. The protocol maintained functionality under both honest scenarios and adversarial conditions where attackers delay transaction and EB releases, indicating robust operation under degraded network conditions.

Validation performance analysis​

Quantile regression analysis​

The team extended ledger operation analysis with comprehensive quantile regressions at 50th, 95th, and 99th percentiles for ledger 'apply' and 'reapply' operations. This analysis addressed concerns about validation time interference between EB reapplication and Praos block release timing.

The quantile analysis provides predictions for full EBs with varying Plutus script intensities, demonstrating that 'apply' operations occur distributed across multiple slots and computational threads. At the same time, 'reapply' operations must complete before new reference blocks (RBs) and EBs can build upon newly certified EBs.

CIP documentation enhancements​

Updated figures and regression validation​

The team regenerated comprehensive figures for CIP inclusion using the upgraded sim-cli version 1.3.0, which included updated diffusion and voting duration configurations. The regression experiment analysis compared performance across simulator versions, revealing minimal discrepancies but slightly reduced performance with version 1.3.0 compared to previous versions.

Next steps​

• Monitor CIP review process and respond to community feedback
• Continue protocol parameter refinement based on ongoing analysis
• Extend network analysis to additional deployment scenarios
• Develop implementation guidelines based on technical report findings.

This week, the Leios team made significant progress on the Cardano Improvement Proposal (CIP) documentation, conducted extensive Plutus validation experiments, and resolved outstanding discrepancies between simulation implementations. The team successfully demonstrated Linear Leios performance under various Plutus workloads and completed comprehensive protocol parameter analysis for CIP inclusion.

CIP development progress​

The team completed substantial portions of the Leios CIP draft, bringing it closer to submission readiness. The specification section is now complete except for network and incentives components, with the motivation and abstract refined for clarity. The first of four main rationale subsections has been fully drafted, providing evidence-based arguments for Leios necessity and viability.

Plutus validation experiments​

The team conducted comprehensive experiments examining Linear Leios performance under varying Plutus computation loads using 6-vCPU nodes at 100 TPS. Key findings from the Plutus validation analysis include:

• Linear Leios successfully supported doubling the Plutus per-transaction budget
• Protocol breakdown occurred at sixfold increases in Plutus budgets due to validation bottlenecks
• Endorser blocks could handle approximately 5,000 execution steps of Plutus computation, representing 250 times the current Praos per-block budget
• This capacity could support either a handful of transactions with 20x greater Plutus budgets or increasing every Plutus transaction budget by 50%
• Late diffusion of Plutus-heavy transactions poses potential risks to EB adoption timing.

The analysis revealed significant variability in CPU time requirements for Plutus scripts relative to their execution steps, highlighting the need for careful resource planning in high-throughput scenarios.

Simulation improvements and comparisons​

Cross-simulation validation​

The team completed another comprehensive comparison between Haskell and Rust simulations at analysis/sims/202532b, successfully resolving previous discrepancies in vote diffusion behavior. This validation ensures both simulation implementations produce consistent results for protocol analysis.

Protocol parameter optimization​

The 2025w32 experiment established a comprehensive set of protocol parameters and throughput scenarios for inclusion in the CIP Evidence section:

• Protocol variant: Linear Leios with conservative resource allocation
• Resource requirements: 4 vCPU per node, 10 Mb/s bandwidth
• Stage configuration: 7 slots each for voting and diffusion stages
• Block limits: Maximum 12 MB transaction references per EB
• Transaction size: 1,500 bytes per transaction with normal Plutus frequency

Key performance findings demonstrate that modest computational resources adequately support throughput up to 0.3 TxMB/s, with 7-slot stages providing sufficient diffusion time while minimizing EB discard probability. The 12 MB EB limit allows occasional peak utilization to compensate for unlucky sortition periods.

Implementation enhancements​

Haskell simulation​

The team addressed head-of-line blocking issues in Linear Leios by implementing message slicing capabilities in the mini-protocol multiplexer, eliminating unexpected delays in vote diffusion. Additional work focused on developing new mini-protocols for enhanced Linear Leios simulation fidelity, with ongoing refinements to balance protocol granularity and sophistication.

Rust simulation​

Implementation of transaction withholding attack scenarios for Linear Leios, where EB producers delay transaction publication until EB release. The simulation also received updates to improve handling of late transactions, EBs, and RBs in Linear Leios scenarios.

Next steps​

• Complete remaining network and incentives sections of the CIP specification
• Finalize mini-protocol designs for enhanced simulation accuracy
• Continue investigation of mempool rule adequacy for high-throughput scenarios
• Expand Plutus validation analysis to cover additional execution budget scenarios.

This week, the Leios team achieved significant milestones in protocol development and analysis, successfully demonstrating high-throughput capabilities and exploring new protocol variants. The team conducted comprehensive experiments with the Stracciatella variant, analyzed the Linear Leios throughput efficiency, and implemented new simulation capabilities.

High-throughput demonstration​

• Completed experiments demonstrating over 1,000 TPS capability with the Stracciatella variant of Leios
• Achieved spatial efficiency above 95% with transaction lifecycle times under two minutes
• Validated protocol performance under extreme throughput conditions well beyond the current Cardano capacity
• Documented detailed findings in the Stracciatella analysis notebook.

Protocol variants analysis​

Stracciatella variant​

• Completed a comprehensive analysis of the Stracciatella variant (no IBs, transaction references in EBs, two-stage pipeline)
• Key findings:
  • 5-slot/stage performs less well but scales better than 8-slot/stage
  • Only a minimal fraction of transactions fail to reach the ledger, likely due to EB expiration
  • Network usage is slightly heavy, while CPU usage appears suspiciously light
  • Congestion begins to appear at throughput levels above 1,000 TPS.

Linear Leios throughput efficiency​

• Conducted an analysis of the Linear Leios variant's probability of including certified EBs on-chain
• Results show Linear Leios could achieve approximately 500 times the throughput of Praos at over 50% network resource efficiency
• 500 times Praos throughput would exceed 1,000 historically typical transactions per second
• Generated comprehensive throughput and efficiency visualizations available in the analysis repository.

CDDL specifications​

• Added CDDL specifications for Linear and Stracciatella protocol variants.

Simulation improvements​

Rust simulation​

• Implemented a first pass of the Linear Leios variant in the Rust simulation
• Enhanced simulation capabilities to support protocol variant testing and analysis
• Continued optimizing simulation performance for high-throughput scenarios.

Small transaction experiments​

• Completed the analysis of small-transaction, high-throughput experiments with 300-byte non-Plutus transactions
• Key findings:
  • 1,000 tx/s with 300 B/tx is feasible in Leios variants
  • Clear time–space tradeoff between variants
  • full-with-ib-references uses space more efficiently than full-without-ibs
  • full-without-ibs has a shorter transaction lifecycle than full-with-ib-references
  • 2 CPU cores are sufficient for high-throughput operation
  • Network usage remains modest under high load
• Supporting materials are available in analysis documentation and analysis notebook.

Next steps​

• Continue investigation of protocol variants for CIP convergence
• Expand simulation capabilities for additional protocol variants
• Refine performance optimization strategies for high-throughput scenarios
• Complete documentation of protocol variant comparisons and recommendations.

This week, the Leios team conducted comprehensive experiments examining protocol variants, conflict handling, and bandwidth requirements. The team also completed the analysis of nine candidate Leios variants with different sharding strategies, performed detailed conflict experiments at 100 TPS, and validated bandwidth requirements across multiple throughput scenarios.

Simulation analysis of protocol variants​

• Completed a comprehensive analysis of nine candidate variants of Leios, examining three basic variants and three sharding strategies:
  • Basic variants: Full, Full without IBs, Full with transaction references
  • Sharding strategies: unsharded, sharded, overcollateralized 1x
• Identified significant differences in spatial and temporal efficiencies across variants:
  • Full with transaction references achieved the highest spatial efficiency (95.999-96.466%)
  • Full without IBs demonstrated the fastest time to the ledger (43.052-43.057s)
  • Sharded variants generally showed improved spatial efficiency but increased latency
• Documented detailed findings in the analysis notebook.

Conflict experiments​

• Conducted experiments exploring the effect of conflicting transactions at 100 TPS using the simplest Leios variant
• Tested scenarios with 0%, 25%, and 50% of transactions conflicting with other transactions
• Key findings from the conflict analysis:
  • Spatial efficiency can be as low as 55% due to occasional IB production before the previous reception
  • All non-conflicted transactions reach the ledger within 75 seconds
  • NIC bandwidth of 20 Mb/s is sufficient for protocol operation
  • Four vCPU cores provide adequate processing capacity
  • Large IBs (up to 2 MB) diffuse globally within five seconds
  • IB traffic does not interfere with other protocol message types.

Bandwidth experiments​

• Completed experiments exploring bandwidth limitations at 100 TPS and 300 TPS documented in the bandwidth analysis
• Validated protocol parameters for high performance: mini-mainnet topology, 1-2 IB/s, 10 slot/stage, 328 kB/IB maximum, 1.5 EB/stage, and multiple shards
• Key performance findings:
  • Achieved 80% spatial efficiency across tested scenarios
  • All transactions reach the ledger within two minutes
  • 30 Mbps NIC bandwidth is sufficient for Leios node operation
  • Four-core vCPU provides adequate processing capacity
  • Insensitive results to inter-nodal link bandwidths above 50 Mb/s
  • Even 10 Mb/s links show minimal impact on protocol performance.

Rust simulation improvements​

• Added support for IB equivocation (work in progress, evaluating impact)
• Implemented minor usability improvements to the CLI tool
• Added sharding support to the 'full without IBs' variant of Leios.

CDDL Version 1​

• finalized and merged a first version of the CDDLs for the current variants in discussion for CIP, here in PR-396.

This week, the team focused on simulation analysis, security improvements, and protocol documentation, making significant progress across multiple areas.

Simulation analysis and performance​

The team executed the first high-throughput simulations of Leios using the Rust simulator, with transaction rates reaching up to 1,000 TPS. They introduced two key efficiency metrics to quantify system performance:

• Temporal efficiency, which measures the fraction of submitted transactions that make it into the ledger, with nearly 100% indicating optimal transaction inclusion
• Spatial efficiency, which represents the ratio of transaction size to total ledger size (including IBs, EBs, and RBs), with higher values indicating better storage optimization.

Recent revisions to Full Short Leios have shown promising improvements in both efficiency metrics. The simulations revealed an average transaction lifecycle of approximately 100 seconds from submission to ledger inclusion.

The analysis produced several key visualizations that demonstrate the system's performance:

Protocol documentation and analysis​

The team conducted an extensive analysis of transaction throughput and block characteristics, producing several key visualizations:

The team also completed a comprehensive profitability analysis for Leios SPOs, considering various deployment scenarios:

• Evaluated infrastructure costs across premium and value cloud providers
• Demonstrated profitability without reserve contributions at 50+ TPS
• Documented the impact of diminishing future rewards due to reserve depletion
• Analyzed comparative economics between Praos and Leios SPOs.

Security and infrastructure improvements​

The team addressed several security vulnerabilities in web applications through a series of patches:

• Fixed minor and moderate security issues in #321, #322, #323, and #325 pull requests.

Protocol enhancements​

Recent protocol improvements include:

• Implementation of revisions to Full Short Leios design to enhance both temporal and spatial efficiency
• Optimization of protocol parameters for improved transaction processing
• Development of a new sharding strategy in Rust simulation
• Enhanced logging system for tracking spatial efficiency metrics.

For more detailed information about the simulations and analysis, please refer to the analysis documentation and the profitability analysis notebook.

This week, the Leios team made significant progress in protocol development, focusing on simulation improvements, network protocol design, and economic analysis. The team completed extensive simulations across 648 scenarios, implemented new mini-protocols for Leios diffusion, and conducted important economic analysis regarding future reward sustainability.

Simulation and analysis​

• Completed comprehensive simulation of 648 scenarios for Full and Short Leios at tag leios-2025w16
• Generated new analysis outputs:
  • Network, disk, and CPU resource usage summaries
  • Interactive "Leios graph" visualization showing transaction, IB, EB, RB, and vote linkages
• Key findings from simulations:
  • Strong agreement between Rust and Haskell implementations
  • Haskell simulation shows network congestion at 16 IB/s
  • Rust simulation demonstrates higher CPU usage at elevated IB rates
  • Identified voting certification issues in Rust implementation.

Protocol development​

Haskell implementation​

• Completed first draft of new mini-protocols for Leios diffusion:
  • IB-relay, EB-relay, Vote-relay for header diffusion
  • IB-fetch, EB-fetch for body diffusion
  • CatchUp protocol for historical blocks
• Renamed short-leios command to leios to reflect full variant support.

Rust implementation​

• Fixed conformance with shared trace format
• Resolved voting logic bug affecting EB certification
• Updated visualization system for documentation site integration.

Economic analysis​

The team conducted a detailed analysis of transaction lifecycle and future reward sustainability:

• Analyzed seven stages of Full Leios transaction processing
• Identified optimal stage lengths and shard configurations
• Estimated two-minute average delay from transaction submission to RB reference
• Projected future IB rates needed to maintain current reward levels:
  • Current Reserve depletion rate: 12.8% per year
  • Required IB rates increase from 0.008 to 0.634 blocks/slot by 2035
  • Analysis assumes constant fee-related protocol parameters.

Next steps​

• Translate transaction lifecycle model to Delta QSD for network effects analysis
• Compare model results with Rust simulator output
• Develop memory-pool and ledger variant models
• Continue investigation of voting certification issues in Rust implementation.