Cisco APIC Layer 3 Networking Configuration Guide, Release 6.2(x)

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Cisco APIC Layer 3 Networking Configuration Guide, Release 6.2(x)

ACI border gateway deployment

Updated: April 17, 2026

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ACI border gateways provide VXLAN connectivity between Cisco ACI and remote VXLAN EVPN domains.

An ACI border gateway deployment provides the following functions:

  • Uses VXLAN as the overlay technology to encapsulate packets and tunnel traffic across the Layer 3 intersite network (ISN).

  • Uses border gateway nodes to provide the VXLAN handoff by stitching VXLAN tunnels between Cisco ACI and VXLAN EVPN domains.

  • Requires border gateways in each pod to enable communication between local endpoints and remote VXLAN EVPN domains.

Deployment architecture

The following figure shows the deployment of ACI border gateways in Cisco ACI:

Figure 1. ACI border gateway deployment in Cisco ACI
Diagram showing the placement of ACI border gateways and the VXLAN connectivity between Cisco ACI and VXLAN EVPN domains.

The deployment architecture has the following characteristics:

  • Layer 2 and Layer 3 VXLAN connectivity between Cisco ACI pods in the same fabric continues to use the spine-to-spine data path through the inter-pod network (IPN).

  • For each bridge domain extended across domains, Cisco ACI elects one border gateway as the designated forwarder from all border gateways in all pods. The designated forwarder sends and receives flood traffic for the bridge domain to and from the remote VXLAN EVPN domain.

ACI border gateways must be present locally in each pod. Without a local ACI border gateway, endpoints in a pod cannot communicate with a remote VXLAN EVPN domain through ACI border gateways deployed in another pod.

Figure 2. ACI border gateway in a pod
Diagram showing an ACI border gateway in a pod and its role as the designated forwarder for bridge domain traffic.

In releases earlier than Cisco ACI Release 6.1(5), you cannot use border gateway nodes deployed in each fabric to establish Layer 2 or Layer 3 connectivity between ACI fabrics. In these releases, ACI border gateways can extend connectivity and policy only to a remote VXLAN EVPN domain.

To extend connectivity and policy between ACI fabrics in releases earlier than Cisco ACI Release 6.1(5), use the ACI Multi-Site architecture. ACI Multi-Site provides intersite connectivity through the spine nodes, as shown in the following figure.

Beginning with Cisco ACI Release 6.1(5), you can establish Layer 2 and Layer 3 connectivity between ACI fabrics by using the border gateway nodes deployed in each fabric.

Figure 3. Layer 2 and Layer 3 connectivity between ACI fabrics before Cisco ACI Release 6.1(5)
Diagram showing Layer 2 and Layer 3 connectivity between ACI fabrics through the spine nodes before Cisco ACI Release 6.1(5).