I believe you are referring to the DGB internal cross-chain communications, or what we call “leader-to-leader” communications. This is a modified RAFT BFT protocol, that simulates a collision domain like an Ethernet LAN channel to avoid needing to designate a leader for the communications (as would be expected for RAFT or similar BFT). In so doing, one DGB parallel chain can send to another DGB parallel chain atomically. This is critical in eliminating the need for a central “beacon” type chain to manage the parallel chains. In turn by eliminating a central beacon type chain, we avoid the problem of “altruistic” nodes that would be needed to run the beacon chain.