Multipath/Reordering

Reordering is caused by the existence of multiple paths between source and destination.
So we implement multiple paths, and route packets to either one basing on some criteria (currently: random decision)

ipfw pipe 1 config bw 2Mbit/s delay 80ms
ipfw pipe 2 config bw 3Mbit/s delay 30ms
ipfw pipe 3 config bw 1Mbit/s delay 100ms
ipfw add 100 prob 0.33 pipe 1 tcp from me to any
ipfw add 100 prob 0.5  pipe 2 tcp from me to any
ipfw add 100 prob 1    pipe 3 tcp from me to any

Each ipfw rule above matches with a given probability. If not match, go to the next rule.

Very simple to implement, very simple to use, very close to reality.