How to go about testing your network for an AlwaysOn implementation
The easiest way to test AG network throughput is to rebuild one of your largest indexes.

While the index rebuild is running (and afterwards), measure the latency for each replica using any of these scripts:


Measuring Availability Group synchronization lag - Derik Hammer
Monitoring Availability Group Replica Synchronization - Jonathan Kehayias


This will give you a rough idea of how far behind each replica gets. If performance doesn't meet your goals, then you can drill into more granular measurements.

Keep in mind that network latency &amp; bandwidth isn't the only issue that can affect replica latency. There's also log file write latency and redo thread throughput on the replicas. Starting at the high level of just checking synchronization lag will tell you whether or not there's a problem at all first, and then you might be able to just avoid drilling down into details altogether - especially since you wrote that this is a DR-only setup, not for HA.