  Consensus protocols can be an effective tool for synchronizing small amounts
of data over small regions. We describe the concept and implementation of
entangled links, applied to data transmission, using the framework of Promise
Theory as a tool to help bring certainty to distributed consensus. Entanglement
describes co-dependent evolution of state. Networks formed by entanglement of
agents keep certain promises: they deliver sequential messages, end-to-end, in
order, and with atomic confirmation of delivery to both ends of the link. These
properties can be used recursively to assure a hierarchy of conditional
promises at any scale. This is a useful property where a consensus of state or
`common knowledge' is required. We intentionally straddle theory and
implementation in this discussion.
