Quote from esmjb:
orders are timestamped at the hub you connect to. from there all the orders are put into a "holding bin" in germany and sorted out by their server. the exchange utilizes a throttle type mechanism to ensure a level playing field for all users located in cities with hubs. so actually a person who enters an order in frankfurt has his order timestamped and then delayed in order for eurex to collect the orders from all the other hubs and then trades are matched up according to the timestamp from the regional hub.