Data Center Interconnect (DCI): Concepts, Drivers, and VXLAN‑Based Solutions
The article explains what a data center is, why interconnecting multiple data centers has become essential for scale, cross‑region access, disaster recovery, and cloud‑native virtualization, and compares two VXLAN‑based DCI architectures—end‑to‑end VXLAN and segment VXLAN—along with the key underlying technologies.
Data Center Interconnect (DCI) is a networking solution that enables multiple data centers to communicate with each other, a need driven by the rapid growth of cloud computing, big data, and artificial intelligence, as well as requirements for cross‑region user access, disaster recovery, and resource pooling.
What is a data center? A modern data center consists of compute systems, storage systems, power/thermal management, and a data center network that links all components and handles all data traffic.
Why DCI is needed? Business scale is expanding quickly, making a single data center insufficient; cross‑region user access demands nearby points of presence; backup and disaster‑recovery require geographically separated sites; and virtualization/resource pooling for cloud‑native environments need seamless inter‑data‑center migration.
Key technology trends include the shift toward cloud‑native data centers where virtual machines (VMs) become the basic unit, requiring network support for VM migration across sites.
DCI solution options
End‑to‑End VXLAN
Multiple data centers share a single VXLAN overlay domain managed by a unified cloud platform and iMaster NCE‑Fabric. Underlay routing must be reachable, and leaf devices in each site run EVPN to discover each other and establish VXLAN tunnels, suitable for Multi‑PoD (same‑city, moderate scale) scenarios.
End‑to‑End VXLAN architecture diagram
Leaf devices exchange VXLAN encapsulation information via EVPN, triggering tunnel creation.
End‑to‑End VXLAN tunnel illustration
Segment VXLAN
Each data center operates as an independent VXLAN domain; a separate DCI VXLAN domain is created to interconnect them. Both intra‑site and inter‑site leaf devices connect to DCI gateways and run EVPN, making this approach suitable for Multi‑Site (different regions or far‑distance) deployments.
Segment VXLAN architecture diagram
Segment VXLAN tunnel illustration
Key DCI technologies include VXLAN (a MAC‑in‑UDP tunnel that extends Layer‑2 over IP), EVPN (a BGP‑based control plane that provides MAC/IP reachability for VXLAN), and optionally RDMA for high‑performance transport.
For further details, see the linked articles on VXLAN fundamentals and RDMA technology.
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