We only transmit what can't be predicted. In some cases we may be able to communicate corrections to predictions if we know the predictions that others will be making. Keep network distance small If latency tends to be worse the further apart computers are on the network, then we should prefer communication with neighbors. Of course, this means we need to measure latency to some extent and use that to determine how much of a neighbor they are. There's no such thing as a free guarantee.
Guarantees always cost something.
We just require that best effort is used. If we need anything further than that then we'll provide it ourselves. So we don't need guarantees for message delivery, message ordering, or message integrity. However, it would be nice to know if a received message is corrupt or not, and what its serial number is, if only to be able to collect some statistics that will give us an idea of how good communication is with a particular party. Bandwidth is precious Bandwidth is precious, so let's not waste it or cause bottlenecks in the system.