Understanding Data Center Interconnect (DCI) and Its VXLAN/EVPN Solutions

What is a Data Center?

A data center is a critical digital infrastructure that provides computing, storage, and forwarding of data, forming the backbone of digital transformation. Its core components include computing systems (general‑purpose and high‑performance modules), storage systems (massive storage, data management engines, dedicated storage networks), energy systems (power, cooling, IT management), and the data center network that connects all these resources.

The general‑purpose compute module directly serves user workloads and relies on a large pool of servers; the network is the "soul" of the data center.

Why Do We Need Data Center Interconnect?

Single data centers can no longer meet the rapid growth of cloud, AI, and big‑data services. Organizations deploy multiple data centers across regions to handle increasing business scale, provide low‑latency access for geographically dispersed users, and ensure disaster‑recovery and backup capabilities.

Rapid business growth – Cloud and intelligent services expand quickly, exhausting the resources of a single data center and requiring additional sites that must be interconnected.

Cross‑region user access – Users expect seamless service regardless of location, prompting enterprises to place data centers near users and interconnect them.

Backup and disaster recovery – To achieve high availability and data reliability, enterprises replicate data and services across distant data centers, which necessitates interconnection.

Virtualization and resource pooling trends – As workloads move to cloud, virtualization and resource pooling become essential; inter‑data‑center connectivity enables VM migration across sites.

Available Data Center Interconnect Solutions

Huawei offers two recommended DCI architectures based on its data‑center networking portfolio (CloudEngine switches, iMaster NCE‑Fabric, and NCE‑FabricInsight).

End‑to‑End VXLAN Solution

This approach creates a unified VXLAN domain across multiple data centers, managed by a single cloud platform and iMaster NCE‑Fabric. VPCs and subnets can span data centers, enabling direct business communication. The architecture requires underlay routing between sites and EVPN on leaf devices to discover each other and exchange VXLAN encapsulation information, establishing end‑to‑end VXLAN tunnels. It is suited for Multi‑PoD scenarios—multiple data centers in the same city or region with moderate scale.

Leaf devices use EVPN to discover peers and trigger VXLAN tunnel establishment.

Segment VXLAN Solution

In this model each data center operates as an independent VXLAN domain managed by its own cloud platform and iMaster NCE‑Fabric. A separate DCI VXLAN domain is created to interconnect the sites. Both intra‑data‑center leaf devices and DCI gateways use EVPN to exchange VXLAN information, forming Segment VXLAN tunnels. This solution fits Multi‑Site scenarios where data centers are geographically dispersed or cannot be managed by a single fabric.

Key Technologies for Data Center Interconnect

VXLAN is a tunneling technology that overlays a Layer‑2 network on any IP‑routable substrate, using MAC‑in‑UDP encapsulation to extend Ethernet domains across IP networks. It enables large‑scale expansion and VM mobility without requiring the underlying network to understand MAC addresses.

EVPN (Ethernet VPN) provides a control plane for VXLAN, using BGP extensions to distribute MAC/IP reachability information, separating control and forwarding planes. The combination of VXLAN and EVPN is now the de‑facto standard for modern DCI deployments.

For deeper technical details, refer to the linked articles on VXLAN and EVPN.