We have a client expanding from 2 to 3 locations, with the newest location designated to be the HQ. We have the added benefit of supporting all 3 locations, and upgrading each location with new Meraki equipment. We have an MX100 at the HQ, and MX68 at each of the other 2 locations. HQ has 50 users, but planning to increase up to 250 soon. The other two locations have fewer than 50 users, with no plans to increase. HQ will be running a Windows server application, all sites need to access.
My question, since we have the ability to dictate local subnets, what is the best practice and/or common configuration for this site to site vpn, knowing the number of users and equipment in play?