Add the design report: Ouroboros Leios: design goals and concepts

And also the initial revision of the CIP

Author: dcoutts

CIP/README.md

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+---
+CIP: TBD
+Title: Implement Ouroboros Leios to increase Cardano throughput
+Authors: Duncan Coutts <[email protected]>
+Status: Draft
+Type: Core
+Created: 2022-11-18
+License: CC-BY-4.0
+---
+
+Included documents: [*Ouroboros Leios: design goals and concepts*](leios-design.pdf)
+
+## Abstract
+
+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.
+
+## Motivation
+
+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.
+
+## Specification
+
+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*](leios-design.pdf)
+
+There may be further updates to this design document over time. The latest
+published version will be available in the
+[IOG research library](https://iohk.io/en/research/library/papers/ouroboros-leios-design-goals-and-concepts/).
+
+## Rationale
+
+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.
+
+## Path to Active
+
+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.
+
+## Copyright
+
+This CIP is licensed under [CC-BY-4.0][].
+
+[CC-BY-4.0]: https://creativecommons.org/licenses/by/4.0/legalcode
+[Apache-2.0]: http://www.apache.org/licenses/LICENSE-2.0
+