Thanks for all the wonderful suggestions. The RB760iGS arrived, I will start testing in-house with copper first, then a manufactured mikrotik sfp optical cable.
AlainCasault:I'm assuming that the /16s are just to summarize local subnets and you don't have such a big network. Otherwise, break the subnet down to smaller ones (like /24).
Indeed, there are multiple vlans in both networks. Only two specific vlans would be "bridged".
AlainCasault:The best example I see of this here is that nobody suggested static routes for ISP redundancy. If one fails, then that building is out of Internet, even though you have a perfectly good (and reachable) one next door.
Great idea. Could you give me pointers on how to configure this? Both buildings have dynamic external IP with PPPoE internet connections.
mkx:I'd use "the other end's" IP address as gateway:
Alright, thanks for the corrections!
Steveocee:You don't want copper between 2 different buildings, add your distance and fibre is the only option.
Yeah, I'll go with fiber. We used to have lightning-related problems.