As you get more and more into Cisco Data Center terminology you come across the term DCI. DCI is a Data Center Interconnect. DCI’s typically come in 3 categories.
Dark Fiber (CWDM/DWDM)
MPLS Layer 2 VPN (VPWS/VPLS)
MPLS Layer 3 VPN
A DCI is basically a LAN extension over one of the above methods.