Weekly Update 2025-03-17 (#268)

* site: weekly update

Author: will-break-it

site/news/2025-03-17-weekly-progress-summary.md

@@ -0,0 +1,42 @@
+---
+title: Weekly Summary – March 17, 2025
+authors:
+- will
+tags: [progress, update, weekly]
+---
+
+This week, the team made great progress in the Leios protocol development, focusing on improving simulation capabilities and understanding the behavior of the protocol in different network conditions. A comparison of Haskell and Rust simulations across [**18 scenarios**](https://github.com/input-output-hk/ouroboros-leios/blob/main/analysis/sims/2025w12/analysis.ipynb) revealed that Leios protocol scales well to mainnet-size networks. However, the protocol tends to experience congestion once the input-block rate reaches 30 IB/s.
+
+## Simulation comparison
+
+- Compared [**18 scenarios**](https://github.com/input-output-hk/ouroboros-leios/blob/main/analysis/sims/2025w12/analysis.ipynb) between Haskell and Rust simulations at tag [`leios-2025w12`](https://github.com/input-output-hk/ouroboros-leios/releases/tag/leios-2025w12)
+- Recent fixes and adjustments enabled meaningful comparison between simulations
+- Identified differences when comparing the Haskell and Rust results, which are under active investigation.
+
+### Analysis of simulations
+
+- Completed the first simulation of Short Leios for varied IB production rate, IB size, and network topology
+- In the simulations, the Leios protocol scales well to mainnet-size networks
+- Identified congestion in the protocol once the input-block rate reaches 30 IB/s
+- Suggested that allowing IBs larger than current Praos RBs may have advantages in TCP efficiency, network usage, and adapting to fluctuating transaction loads.
+
+| Peak CPU                                                                                                               | Mean CPU                                                                                                               |
+|------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------|
+| ![analysis/sims/2025w12xl/plots/cpu-peak-histogram-rust.png](https://github.com/input-output-hk/ouroboros-leios/raw/main/analysis/sims/2025w12xl/plots/cpu-peak-histogram-rust.png) | ![analysis/sims/2025w12xl/plots/cpu-mean-histogram-rust.png](https://github.com/input-output-hk/ouroboros-leios/raw/main/analysis/sims/2025w12xl/plots/cpu-mean-histogram-rust.png) |
+
+### HasKell simulation
+
+- Implemented expiration of blocks
+  - Blocks are cleared from relay buffer as soon as they should stop diffusing, then cleared from other state as specified
+- Implemented first stab at Full Leios implementation
+  - Only lightly tested so far
+  - Added `praos-chain-quality` configuration parameter for the `\eta` parameter from the spec.
+
+### Rust simulation
+
+- Implemented first pass at Full Leios, with guesses for some parameters.
+
+### Formal methods
+
+- Short Leios trace verification: For Short Leios, we are modelling the local state evolution of a node
+- Developed the initial trace verifier for Short Leios simulation traces in `leios-trace-verifier`.