**AMQP**

Use an AMQP implementation to guarantee node updates go to *all* masters. This will take care of having the data on all master sync'd. There are free AMPQ implementations (as well as non-free). You would probably want to run some test to figure out the appropriate tolerances, etc. Gigabit interconnects will support quite a bit of queued communication, assuming the update rate is not extremely high, and the average update is not huge. YYMV, so you'll definitely want to run some numbers, and do some testing to back it up.