| CIP | Title | Authors | Status | Type | Created | License |
|---|---|---|---|---|---|---|
79 |
Implement Ouroboros Leios to increase Cardano throughput |
Duncan Coutts <duncan.coutts@iohk.io> |
Draft |
Core |
2022-11-18 |
CC-BY-4.0 |
Included documents: Ouroboros Leios: design goals and concepts
As Cardano evolves, there will be increasing demand for greater network capacity to support new and existing users and applications. The long term solution is to rebase Cardano on the new Ouroboros Leios protocol. Ouroboros Leios is a new member of the Ouroboros family that is designed specifically for high throughput, without compromising security. This will meet expected future demands, providing a basis for continuing Cardano growth and scalability.
Cardano's current throughput (measured both in data rate and available script execution time) is adequate for the current demand. There is also some opportunity to increase the block sizes and script execution limits to meet emerging future demands for increased network capacity. There are however fundamental limits to how far the block size and the script execution budget can be pushed, while maintaining system security.
Under Ouroboros Praos, in order to ensure the security of the overall system, blocks must be distributed across the network reliably in "$\Delta$" time slots. This is set to be 5 seconds on the Cardano mainnet. The block relaying process is an essentially serial process: blocks must be relayed between consecutive block producer nodes through a series of intermediate relay nodes. The overall time that this takes is proportional to the number of network hops between one block producer and the next, and the network latency of each of those hops (which must in general span the whole globe). Given that this must always happen within 5 seconds, this puts a hard upper limit on how large each block can be and also on how much time can be spent validating transactions and scripts.
In order to substantially scale beyond this requires changes to the underlying blockchain algorithm. There are significant opportunities to scale: the network and CPU resources on most nodes are almost idle much of the time. With a different algorithm, these resources can be used to increase the total chain bandwidth.
Ouroboros Leios is a substantial new design. To do it justice, we do not include it in full in this README. Instead, as part of this CIP we include a larger document that describes Ouroboros Leios in much more detail:
Ouroboros Leios: design goals and concepts
There may be further updates to this design document over time. The latest published version will be available in the IOG research library.
The included document sets out in more detail the limitations of the existing design, the goals for the new design, and a design strategy that lead to the proposed Ouroboros Leios design. It explains how the new design relates to existing features. It sets out a very high level development strategy for how Ouroboros Leios can be developed and integrated into Cardano.
The path to the implementation of Ouroboros Leios within Cardano will be a long one, as it will require substantial research, development and integration effort. The proposed high level development strategy is set out in the linked document.
This CIP is licensed under CC-BY-4.0.