Hub Bandwidth management

Balancing hub bandwidth between users requires triage of messages such that no individual user can monopolize hub bandwidth. Repeatedly I have observed a temptation to implement such an idea by limiting different messages differently. Whilst such an idea fails somewhat for NMDC, ADC is an open-ended protocol which separates message types from message contents, leading to more significant design failure. This post addresses hubs for which the limiting resource is upload bandwidth. Those hubs limited by CPU or RAM have separate issues and those limited by their own download bandwidth are effectively under DoS attack. Within this constraint, the cost to a hub of a user’s message is the uploaded data triggered for the hub by that message. Therefore, broadcast-type messages should generally dominate hub bandwidth; empirical data bears this out. To a first approximation, then, one can ignore non-broadcast messages, as well as INF, which must be specially handled by a hub regardless. Both merely large number ...