The amount of bandwidth required will be a function of two details. 1) what is the timeframe that the change takes place over? ie. does the 1gb change happen in 1 hr, 1 day, or 1 week? and 2) Since this remote mirroring will be async, how much delta between the databases are you willing to allow? ie. can the remote be 1 min out of sync, 10 min out of sync, or more? Since most db work is bursty, if we are given longer periods to sync the data, we can use a lower bw link.
These two questions need to be thought about and answered before a good answer can be given. You need to balance the cost of lost data vs. the cost of higher throughput circuits.
