Cardano has moved a step closer to a planned 15-fold increase in transaction capacity after developers merged core components of its Leios scaling system.
The network’s consensus team integrated Praos2 – a combination of Cardano’s existing consensus protocol and Leios – into its main development branch, according to a development report.
LeiosNotify and LeiosFetch were also merged. They allow network nodes to share information needed to process additional transaction batches, although the systems for selecting and retrieving those batches, known as endorser blocks, are still being developed.
Input Output (IOG) plans to introduce Leios through the forthcoming Dijkstra hard fork. Its initial target is to increase processing capacity by three to five times, with at least two further adjustments intended to take the network to between 10 and 15 times its current limit.
Those later increases will depend on performance testing and separate governance votes, meaning the timetable for reaching Cardano’s full scaling target remains uncertain.
Dijkstra testnet transition still to come
Cardano has not yet begun testing Dijkstra’s new protocol rules on its public testnet.
Intersect, the member-based organisation responsible for maintaining the network’s continuity, said on 24 October that the testnet – restarted three days earlier – was still running Cardano’s existing Conway rules on node version 11.1.3.
Moving to Dijkstra’s protocol version 12 will require the forthcoming node 11.2 prerelease and a hard-fork initiation action.
Developers have also revised the Leios prototype to improve checks on endorser-block announcements and cryptographic certificates. The new Leios header format is now restricted to Dijkstra and later protocol versions.
Those changes require the prototype testnet to restart from its initial state and participating nodes to be updated. The restart will not affect Cardano’s existing mainnet.
Cardano’s current Ouroboros Praos system has an estimated throughput ceiling of about 4.5 kilobytes of transaction data per second. IOG says that limit is partly linked to the need for blocks to spread quickly enough to maintain consensus.
Leios will use endorser blocks to allow extra transactions to be validated and certified separately from normal block production. The first stage is expected to deliver about 13.5 to 22.5 kilobytes per second, while later increases could take capacity to between 45 and 67.5 kilobytes. The number of transactions processed will vary according to their size and computational demands.
Governance approvals required
Before the higher limits can be introduced, Cardano must complete the governance framework for Dijkstra’s operating parameters.
The process begins with a constitutional amendment setting permitted parameter ranges. It needs backing from delegated representatives controlling at least 75% of the relevant voting stake and two-thirds of the Constitutional Committee.
Intersect said the proposal, known as CAP-12, reached its fourth draft in October, with numerical limits, pledge leverage settings and procedures for disabling Leios still unresolved.
The hard fork requires separate support from representatives of 60% of stake, stake-pool operators representing 51%, and two-thirds of the committee.
After Dijkstra goes live, operators must register BLS cryptographic keys to certify Leios endorser blocks. IOG estimates that keys representing 90% to 95% of delegated stake should be registered before activation.
Leios requires signatures from at least 75% of active stake. Pools without BLS keys will still be able to produce ordinary blocks but cannot vote on endorser blocks.
Controlled high-load tests on Cardano’s mainnet will then assess transaction-batch propagation, certification reliability and spare processing capacity. The results will inform proposals for higher limits.
Each subsequent adjustment requires 67% support from delegated representatives, 51% from stake-pool operators and two-thirds approval from the Constitutional Committee, but no further hard fork will be needed if the changes remain within the approved constitutional limits.
