EPaxos Egalitarian Paxos
A consensus protocol with no leader, where any node may propose directly and the ordering between operations is only pinned down when they actually affect each other.
Raft and multi-Paxos pay two prices for their leader: every client has to reach that particular node no matter where in the world it sits, and a leader failure halts the system through an election. Moraru et al. presented an alternative in 2013 where a node sends its proposal straight to a quorum and simultaneously asks which earlier operations it needs to come after. If two operations touch different key spaces they are independent and may hold in any order, which is the common case — then one round trip suffices. On a real conflict, one more is needed. The downside is the execution step: nodes build a dependency graph that must be de-cycled and topologically ordered locally, which is hard to get right and hard to make fast. The ideas live on, notably in Cassandra's Accord protocol.