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 focused on comparative analysis between simulation implementations and conducted experiments examining the impact of protocol parameters and network topology on Linear Leios performance. The team made progress in cross-validation between Haskell and Rust simulations while investigating protocol behavior under different network conditions.

Cross-simulation analysis​

Haskell vs Rust Linear Leios comparison​

The team completed a comprehensive comparison between the early draft Haskell simulator and the more mature Rust simulator for Linear Leios. Key findings from the analysis documented in analysis/sims/2025w31b/analysis.ipynb revealed several discrepancies requiring investigation:

• CPU usage patterns differed between implementations
• Network usage showed variations across simulators
• Vote diffusion behavior exhibited inconsistencies
• Active investigation underway to resolve implementation differences.

Protocol parameter experiments​

Stage length analysis for "No IBs" Leios​

The team conducted experiments varying the stage-length protocol parameter from 5 to 12 slots per stage in "No IBs" Leios. Results documented in analysis/sims/2025w31/analysis.ipynb showed:

• Settlement time remains relatively stable across the tested parameter range
• Stage length has minimal impact on transaction processing times within 5-12 slot range
• Larger stage lengths result in less frequent voting periods
• Protocol performance appears robust to moderate stage length variations.

Network topology validation​

Mini-mainnet vs pseudo-mainnet comparison​

The team completed a comparative analysis of Linear Leios performance across different network topologies using the Rust simulator. Key findings from analysis/sims/2025w30b/analysis.ipynb include:

• The 750-node mini-mainnet network proved slightly more stressful to the protocol than the 10,000-node pseudo-mainnet
• No substantial differences in simulation results between the two network configurations
• Both networks produce equivalent findings and conclusions for protocol analysis
• Validation confirms the mini-mainnet topology as a suitable proxy for larger-scale analysis.

Rust simulation enhancements​

Linear Leios attack modeling​

• Added equivocation voting delay functionality to Linear Leios implementation
• Implemented attack scenario modeling where endorser block (EB) diffusion is deliberately delayed until the last moment
• Enhanced simulation capabilities for security analysis and adversarial behavior testing.

Next steps​

• Continue investigation of discrepancies between Haskell and Rust Linear Leios implementations
• Expand parameter sensitivity analysis for additional protocol variants
• Refine attack modeling capabilities for comprehensive security assessment
• Apply lessons from network topology comparison to future experimental design.

This week, the Leios team made significant progress on CIP development, refined validation timing analysis with improved methodologies, and achieved high-throughput validation milestones. The team completed major components of the CIP specification, proposed improved throughput metrics for better comparability, and demonstrated a 1,000 TPS capability with specific protocol variants.

CIP development progress​

Protocol specification completion​

• Completed a comprehensive review of the protocol overview, component flow, and parameters
• Integrated vote and certificate specifications into the CIP documentation
• Drafted node behavior and network specifications, including mini-protocol definitions
• Progressed the CIP towards completion, with all core protocol components now fully specified.

Throughput metrics standardization​

Improved measurement methodology​

• Proposed transition from transaction-per-second (Tx/s) to transaction-bytes-per-second (TxB/s) metrics for enhanced comparability
• Recommended using Tx/s only in introductory statements with transaction size context (eg, '100 Tx/s with 1,400 B transactions')
• Established TxkB/s and TxMB/s as primary throughput metrics for analysis
• Benefits include:
  • Direct comparability across different transaction sizes
  • Clear nominal storage and network demand calculations
  • Example: 100 Tx/s with 1,400 B transactions = 140 TxkB/s = ~12 GB/day storage
  • Network overhead calculation: 140 TxkB/s × 10 peers = 11.2 Mb/s.

Enhanced validation analysis​

Revised Cardano validation timing study​

• Completed a refined analysis of Cardano mainnet validation times using a clean dataset on an idle machine
• Significantly improved accuracy over preliminary results by eliminating CPU contention effects
• Updated findings for transaction signature verification and Plutus script execution:
  • Median times: 428.4 μs/tx and 211.5 μs/kB
  • Linear model: 148.1 μs/tx plus 114.1 μs/kB
  • Enhanced model: 137.5 μs/tx plus 60.2 μs/kB plus 585.2 μs/Gstep with Laplace error distribution
• Results are suitable for bulk block estimates despite individual transaction prediction limitations
• Findings support reducing CPU-timing parameters in default Leios simulation configurations
• A comprehensive analysis is available in the validation timing documentation.

High-throughput protocol validation​

1,000 TPS Linear Leios demonstration​

• Successfully demonstrated Linear Leios with transaction references supporting 1,000 tx/s at 300 B/tx
• Validated Stracciatella variant capability at 1,000 TPS throughput levels
• Confirmed that Linear Leios with embedded transactions cannot sustain such throughput
• Results provide clear protocol variant performance boundaries for high-throughput scenarios
• Detailed evidence and analysis are available in the 1,000 TPS study notebook.

Simulation infrastructure improvements​

Rust simulation documentation​

• Enhanced the documentation of the current Rust simulation implementation
• Documented available protocol variants and their implementation status
• Improved accessibility and usability of the simulation framework for protocol development.

Next steps​

• Finalize CIP documentation for community review and feedback
• Implement standardized throughput metrics across analysis frameworks
• Apply revised validation timing parameters to simulation configurations
• Expand high-throughput testing to additional protocol variants and scenarios.

This week, the Leios team focused on improving simulation analysis, conducting validation time studies, and working on comprehensive protocol variant experiments. The team developed new analysis tools, conducted fundamental performance studies of Cardano validation times, and completed extensive mapping of Linear Leios protocol performance under various conditions.

Analysis tools and infrastructure​

Generic trace analysis framework​

• Developed a generic analysis script for processing Leios simulator output
• Created a comprehensive R-based analysis pipeline generating diagnostic plots from leios-simulation-trace-processor output
• Enhanced analysis capabilities for systematic evaluation of simulation results
• Documentation and usage instructions are available in the trace processor README.

Validation performance analysis​

Cardano mainnet validation timing study​

• Completed a preliminary analysis of block and transaction validation times for Cardano mainnet since epoch 350
• Key findings using the db-analyser tool include:
  • Median transaction signature verification: 0.53 ms/tx
  • Median validation time per kilobyte: 0.29 ms/kB
  • Joint linear model estimate: 0.066 ms/tx plus 0.221 ms/kB
  • Data suitable for bulk estimates but too noisy for individual transaction predictions
• Identified missing explanatory variables (UTXO set size, input/output counts) extractable from the ledger or cardano-db-sync
• Results provide a foundation for more accurate simulator validation time modeling
• Detailed analysis is available in the validation timing notebook.

Simulation optimization studies​

Timestep resolution analysis​

• Conducted a comparative study of simulation timestep effects at 1,000 TPS Full Leios scenarios
• Compared 0.100 ms and 0.025 ms time resolutions with no significant differences in results
• Validated the use of coarser timesteps for improved parallelism and reduced simulation runtime
• Supporting analysis and evidence are available in the timestep study notebook.

Protocol variant experiments​

Mid-throughput protocol validation​

• Completed 100 TPS experiments for Stracciatella and Linear Leios variants using 1,400 B/tx over 900 seconds
• Key findings include:
  • 5 slots/stages are insufficient for Linear Leios at 100 tx/s
  • Including transactions in EBs causes congestion compared to transaction references
  • 10 MB/EB is required for 100 tx/s performance (5 MB/EB is insufficient)
  • EB-sortition unluckiness in Stracciatella extends the transaction lifecycle but can be mitigated
  • CPU and network peaks occur when transactions are embedded in EBs
• Analysis artifacts are available in 100 TPS experiment documentation and the analysis notebook.

Comprehensive Linear Leios performance mapping​

• Completed an extensive simulation study mapping Linear Leios performance under various loads and configurations
• Compared multiple Linear Leios variants against the Stracciatella baseline
• Generated comprehensive performance characterizations across different throughput scenarios
• Results are documented in the Linear Leios summary with variant-specific analysis:
  • Linear Leios with embedded transactions
  • Linear Leios with transaction references
  • Linear Leios without transactions
  • Stracciatella baseline comparison.

Simulation model refinements​

• Revised the Linear Leios model based on analysis findings, particularly regarding partial EB validation before peer propagation
• Reimplemented Stracciatella as a separate simulation to identify specification deviations
• Identified and resolved multiple implementation inconsistencies during the specification verification process.

Next steps​

• Continue developing analysis infrastructure for systematic protocol evaluation
• Integrate improved validation timing models into simulation configurations
• Expand protocol variant testing based on performance mapping results
• Refine simulation models for enhanced accuracy and specification compliance.

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 achieved a significant milestone by successfully demonstrating protocol viability at 1,000 TPS. They also completed a comprehensive attack surface analysis and made substantial improvements to simulation and verification tools.

High-throughput demonstration​

• Successfully completed a 1,000 TPS experiment using basic 300-byte non-Plutus transactions
• Demonstrated the viability of Leios protocol operation at extremely high throughput levels
• Validated protocol performance under stress conditions significantly beyond current Cardano capacity
• Documented detailed findings in the 1,000 TPS analysis.

Security analysis​

• Completed a comprehensive attack surface analysis for the second technical report
• Defined terminology and taxonomy for potential Leios attack vectors
• Categorized major attack types and their potential impacts on protocol security
• Enhanced understanding of protocol vulnerabilities and mitigation strategies.

Rust simulation enhancements​

• Finished implementing support for input block (IB) equivocations in the simulation
• Added capability to model and analyze protocol behavior under adversarial conditions
• Enhanced simulation fidelity for security-related protocol testing.

Trace verifier performance optimization​

• Achieved 3x performance improvement by configuring minimum heap size to 1GB
• Reduced garbage collection overhead from 75% to 2% of execution time
• Enhanced profiling capabilities with detailed performance analysis tools
• Improved verification efficiency for large-scale simulation trace analysis.

Protocol convergence for CIP​

• Intensified efforts to converge on a specific Leios variant for the Cardano Improvement Proposal (CIP)
• Applied systematic evaluation methodology to rank protocol candidates from multiple angles
• Evaluated efficiency metrics, including temporal efficiency versus storage optimization trade-offs
• Assessed attack surface and security vectors across different protocol variants
• Analyzed utility factors, including quality of service, developer friendliness, user experience, and downstream ecosystem impacts
• Focused on eliminating candidates through evidence-based assessment of valuable protocol characteristics.

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 Leios team conducted extensive experiments using the previously developed network topologies to study transaction and input block throughput limits under realistic conditions. The team also conducted empirical bandwidth measurements between data centers, advanced formal methods capabilities, and created initial CDDL specifications for core Leios components.

CDDL specification draft​

• Created initial CDDL specifications for core Leios components:
  • Input blocks with VRF lottery and single IB/slot limits
  • Endorser blocks as a new aggregation block type
  • Ranking blocks as Conway extension with optional certificates
  • BLS voting system with persistent/non-persistent voters and key registration
• Followed crypto-benchmarks implementation approach while maintaining Conway CDDL compatibility
• Established foundational structures in the first draft covering common base components
• Future iterations will add detailed specifications for design variants, including full sharding, overcollateralization, and protocol extensions.

Formal methods​

• Added support for Late IB inclusion to the formal specification of Full-Short Leios
• Profiled leios-trace-verifier performance, identifying that approximately 60% of execution time is spent in garbage collection
• Improved performance significantly by switching to --nonmoving-gc garbage collection strategy.

Bandwidth measurements​

• Conducted empirical bandwidth measurements using iperf3 between data centers in North America and Europe
• Measured bidirectional connections across multiple cloud providers (OVH, AWS, CenturyLink)
• Results ranged from 95 Mbps to 973 Mbps, depending on geographic distance and the provider
• Identified 100 Mbps as a conservative lower bound for inter-datacenter connections
• Observed 5-20% reduction in individual link speeds when multiple simultaneous connections are active.

Large-scale network experiments​

• Conducted comprehensive experiments using both the 750-node and 10,000-node network topologies with Haskell and Rust simulations
• Studied transaction and IB throughput limits for realistic scenarios up to 300 TPS and 32 IB/s
• Key findings from the 750-node mini-mainnet experiments are documented in analysis results and summary slides:
  • The 750-node mini-mainnet serves as a suitable replacement for the 10,000-node pseudo mainnet for performance measurements
  • Substantial agreement between Haskell and Rust simulations for mini-mainnet scenarios
  • Block propagation times under one second, consistent with empirical observations from pooltool.io
  • Protocol can support 25 MB/s throughput with 1 Gb/s links before degradation
  • Mean transaction time from mempool to ledger is approximately 150 seconds
  • Achieved 80% disk-space efficiency with ~20% network traffic overhead
  • Six-core VM is sufficient for peak demand at 300 TPS, with average demand under two cores
• Results from 10,000-node pseudo-mainnet experiments are available in analysis documentation and presentation slides:
  • Average transaction lifecycle of 100 seconds from mempool to ledger
  • Approximately 80% efficiency for both disk and network usage
  • Six CPU cores are sufficient for peak load handling even at high TPS rates
  • Block propagation time averaged under one second across the large network.

This week, the Leios team focused on improving simulation analysis tools and creating more practical network topologies. Key achievements include enhancing the trace processor with additional data extraction capabilities and developing a smaller, more efficient 'miniature mainnet' topology for repeated experimentation.

Trace processor enhancements​

• Enhanced the leios-trace-processor to extract CPU, resource, and message-receipt data from simulation trace files
• Eliminated the need for using older, lower-performance scripts for analyzing simulation results
• Added comprehensive data output options:
  • Transaction lifecycle data
  • CPU utilization metrics
  • Resource consumption data
  • Message receipt tracking
• Improved analysis efficiency for large simulation datasets.

Miniature mainnet topology​

• Created a more practical 750-node topology that faithfully mimics mainnet characteristics while addressing performance limitations of the 10,000-node pseudo-mainnet
• Achieved a network diameter, stake distribution, and edge degree closely matching those of the mainnet
• Key network metrics:
  • 216 block producers and 534 relay nodes
  • 19,314 total connections with 5-hop network diameter
  • Average of 25.75 connections per node
  • Clustering coefficient of 0.332
  • Average latency of 64.8ms with maximum of 578.3ms
  • 84.85% asymmetry ratio
• Documented the methodology and results in topology-v2.ipynb
• Deployed the network configuration in topology-v2.yaml
• Enabled more practical, repeatable experimentation with realistic network characteristics.

This week, the Leios team focused on infrastructure improvements, formal methods advancement, and large-scale network simulation. The team successfully resolved outstanding CI issues, enhanced the formal specification with Full-Short Leios support, and began simulating a realistic 10,000-node pseudo-mainnet topology.

Infrastructure improvements​

• Fixed outstanding CI bugs #368 and #379, enabling all CI checks to pass.

Formal methods advancement​

• Added Full-Short Leios as a special case of Short Leios to the formal specification
• Implemented trace verification capabilities for Full-Short Leios.

Pseudo-mainnet topology simulation​

• Designed and initiated comprehensive simulations from 1 to 300 TPS using the new pseudo-mainnet topology
• Created a realistic 10,000-node network with:
  • 2,657 block producers and 7,343 relay nodes
  • Realistic stake distribution and geographic distribution
  • Two relays per block producer with realistic latencies
  • 298,756 total connections with 6-hop network diameter
• Observed significant performance challenges within the large-scale simulation:
  • Rust simulation: six minutes of network time in 10 hours at one TPS
  • Performance degradation at higher TPS rates (one minute network time in 10 hours at 300 TPS)
  • Haskell simulation requires optimization for practical large-network analysis.

Rust simulation enhancements​

• Implemented random sampling of transactions from the Leios memory pool to ensure different IBs contain different transactions when possible
• Added simulation support for the Leios variant, where IBs contain transaction references rather than full transaction bodies
• Enhanced transaction handling for high-traffic scenarios.

Analysis of conflicts and incentives​

• Completed comprehensive analysis of transaction conflicts, ledger design, and fee incentives
• Key findings on conflict management:
  • Honest duplicates and conflicts are unavoidable with local sortition
  • Memory pool rules can minimize conflicts through prompt transaction removal
  • Collateral requirements for failed transactions conflict with Cardano's guarantees
• Identified block producer compensation strategies for handling conflicting transactions
• Proposed EB-level optimization through bitmap-based transaction validation to reduce persistent storage of duplicates and conflicts.