Unlike traditional sharding designs, based on the explicit partitioning of the network’s state, our solution centres on the concept of subnets that can be spawned on-demand to manage new state. Subnets are organised in a hierarchy, in which parent subnets are firewalled from child subnets, have their own policies, and run a different consensus algorithm, increasing the network’s capacity and enabling new applications. Subnets leverage the security of parent subnets by periodically checkpointing state and include mechanisms to interact with other subnets in the system. IPC subnets can be configured to resemble different L2 platforms: from an optimistic or ZK-rollup, to a side-chain with a native communication bridge.

Fendermint is an effort to implement IPC with Tendermint. It combines FVM, IPLD, and CometBFT to provide a robust subnet node implementation, which retains compatibility with the Ethereum API and with the IPC actors.

Mir is a framework for implementing, debugging, and analyzing distributed protocols. We use Mir to implement Trantor, a state machine replication system that establishes a total order of client requests with typical liveness and safety properties. Trantor achieves scalability without requiring a primary node to periodically decide on the protocol configuration. It multiplexes multiple instances of a leader-driven consensus protocol which operate concurrently and almost independently.