Datacenter connection via dark fiber

Hello Everyone,

I just want to understand what does it take to connect two datacenters about a couple miles apart using dark fiber. In other words, The brocade DCX SAN switches in each datacenter needs to be connected so that hosts can access storage from either datacenter, so what networking equipment is needed apart from the SAN switches and the dark fiber?. In yet other words, what networking equipment usually exists in between the dark fiber ports of the SAN switches in such datacenters?. Please assist. Thank you.