4 posts tagged with "proposed-leios"

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 refined attack analysis methodologies, conducted critical bandwidth limitation experiments, and updated simulation components for CIP documentation. The team successfully demonstrated proposed Leios behavior under constrained network conditions and validated attack experiment findings with improved simulation models.

Attack analysis refinement​

Late-release attack validation​

The team completed validation of the late-release attack experiment using the latest version of the Rust simulation infrastructure. The rerun confirmed previous findings regarding adversarial impact on proposed Leios throughput, strengthening confidence in the protocol's characterized attack resistance properties under the tested scenarios.

Enhanced CIP simulation experiments​

The simulation experiment for CIP figures received comprehensive updates with the latest Rust simulation version, incorporating several critical improvements. The enhanced experiments feature semi-optimal protocol parameter settings, improved assumptions for validation costs, and expanded exploration of increased Plutus execution step effects. These refinements provide more accurate performance predictions for CIP documentation.

Network performance analysis​

Bandwidth limitation experiments​

The team conducted comprehensive bandwidth constraint analysis examining proposed Leios operation under severely constrained network conditions. The experiments systematically reduced inter-node bandwidth to values as low as 1 Mb/s to determine minimum network requirements for protocol viability.

Key findings demonstrate that proposed Leios operates successfully at 0.250 TxkB/s throughput even with constrained 2 Mb/s bandwidth between nodes. However, the protocol experiences breakdown at 1 Mb/s bandwidth limitations, establishing critical minimum network requirements for deployment scenarios. These results provide essential constraints for infrastructure planning and protocol parameter optimization.

Simulation infrastructure enhancements​

Cross-simulation validation framework​

The team expanded the regression analysis framework to systematically compare all tagged versions of the Rust simulator against consistent network topology and configuration parameters. This approach accelerates detection of behavioral changes across simulator versions and ensures consistent experimental foundations for protocol analysis.

Updated validation models​

Simulation infrastructure received updated transaction validation CPU models that improve accuracy of computational cost predictions. These enhanced models provide more reliable estimates for proposed Leios performance under various workload scenarios and support more precise parameter optimization for different deployment environments.

Next steps​

• Conduct comprehensive network topology degradation experiments
• Extend bandwidth analysis to examine intermediate constraint levels
• Integrate improved validation models into CIP performance projections
• Finalize attack resistance documentation for formal CIP submission.

This week, the Leios team conducted comprehensive attack parameter analysis, released updated simulation tools, and performed detailed analysis of Cardano mainnet validation performance. The team successfully characterized the effectiveness of late-release attacks across different parameter ranges and established baseline performance metrics for ledger operations critical to proposed Leios implementation.

Attack analysis and parameter optimization​

Parameter-sweep experiment for late-EB attacks​

The team conducted a comprehensive parameter-sweep experiment to determine optimal adversarial strategies for late Endorser Block (EB) attacks. The experiment systematically varied EB delay timing from six to eight seconds with adversaries controlling 33% of stake, examining both diffusion parameter configurations (L_diff on/off) under the txs-received propagation scheme.

Critical findings from the parameter sweep analysis demonstrate that efficiency degradation begins when EBs and transactions are delayed 6.5 seconds, with minimal additional impact beyond 7-second delays. The analysis revealed that L_diff = 0s configurations perform better than L_diff = 7s under adversarial conditions. Importantly, none of the tested scenarios using txs-received propagation resulted in transaction loss or protocol breakdown, indicating robust behavior under these attack conditions.

Simulation infrastructure improvements​

Rust simulation releases​

The team released versions 1.1.0 and 1.2.0 of the Rust simulation infrastructure, incorporating updated transaction validation CPU models that improve accuracy of performance predictions. These releases enhance the fidelity of proposed Leios simulations and provide more reliable computational cost estimates for protocol analysis.

Regression analysis framework​

The team implemented a comprehensive regression analysis framework comparing behavior across all tagged versions of the Rust simulator sim-cli. This systematic approach enables rapid detection of behavioral changes in the simulator across development iterations, ensuring consistency and reliability in experimental results.

Mainnet performance analysis​

Cardano mainnet validation timing analysis​

The team extended the analysis of ledger operations with comprehensive linear statistical models predicting Apply and Reapply phases of ledger updates. These regressions provide crucial input for proposed Leios performance studies, particularly scenarios involving higher Plutus execution limits.

Empty block diffusion analysis​

The team completed analysis of empty block diffusion on Cardano mainnet using data from pooltool.io. This analysis establishes empirical estimates for the Δ_hdr parameter required by the proposed Leios protocol. The findings demonstrate that 94.0% of empty Praos blocks arrive at nodes within one second of their slot start time, providing critical timing constraints for protocol parameter selection.

Next steps​

• Continue refinement of attack resistance analysis based on parameter sweep findings
• Integrate updated CPU models into comprehensive protocol performance evaluations
• Extend mainnet analysis to inform proposed Leios parameter optimization
• Prepare comprehensive attack analysis documentation for CIP inclusion.

This week, the Leios team advanced the Cardano Improvement Proposal (CIP) documentation, conducted comprehensive attack analysis experiments, and continued cross-validation between simulation implementations. The team successfully demonstrated resilience characteristics of proposed Leios under adversarial conditions and refined protocol specification components for the formal CIP submission.

CIP development progress​

The team made substantial progress on the Ouroboros Leios CIP proposal. The draft specification section is now complete except for the network and incentives components. The motivation and abstract sections have been refined for clarity, enhancing the document's accessibility and technical precision. The first of four main rationale subsections has been fully drafted, providing evidence-based arguments for the necessity and viability of the proposed Leios protocol enhancement.

Attack resistance analysis​

Initial adversarial simulation experiments​

The team conducted the first simulation experiment for attacks, examining late Endorser Block (EB) and transaction diffusion scenarios where adversaries control timing of critical protocol messages. The experiment varied the diffusion parameter L_diff and EB propagation schemes to assess protocol robustness under different adversarial strategies.

Key findings from the initial attack analysis include successful demonstration that late-release attacks can impact proposed Leios throughput under specific conditions. The analysis revealed that transaction loss occurred in some scenarios due to memory pool rule formulations in the simulator, leading to important insights for protocol hardening and implementation requirements.

Cross-simulation validation​

Haskell versus Rust comparison​

The team completed another comprehensive comparison between Haskell and Rust simulation implementations at analysis/sims/202532b. Results indicate successful resolution of previous discrepancies in vote diffusion behavior between the two simulation environments. This validation ensures both implementations produce consistent results for protocol analysis and strengthens confidence in the simulation-based evidence supporting the CIP.

CIP figure preparation​

The experiment for draft figures for CIP progressed with updated simulation runs designed to generate publication-quality performance charts and protocol behavior visualizations for inclusion in the formal CIP documentation.

Next steps​

• Complete the remaining network and incentives sections of the CIP specification
• Conduct follow-up analysis on attack experiment findings to refine protocol parameters
• Continue refinement of memory pool rules based on adversarial scenario insights
• Finalize CIP figures and supporting analysis for submission preparation.