Consider the following PLAN program :
fun ping_pong(pingHost:host, pongHost:host) : unit =
OnRemote (ping_pong (pongHost, pingHost),
pongHost, getRB (), defaultRoute)
A very simple program to write and run, but if this program were to be left loose on the network (without any resource bound control), it would keep shuttling between two hosts and eat up costly bandwidth.