Data Center Interconnect (DCI) extends networks between sites. You need DCI for disaster recovery, workload distribution, and live migration.
DCI requirements:
- High bandwidth between sites
- Low latency for synchronous replication
- Layer extension for VM migration
- Redundant paths for failover
DCI technologies:
Dark fiber: Your own fiber. Lowest latency. Highest cost.
DWDM: Multiple signals on one fiber.
MPLS VPN: Carrier connectivity.
VXLAN over WAN: Extend VXLAN between sites with BGP EVPN.