Understanding Network Structure of an ACI Fabric

By following the steps below, you can view the detailed information about a tenant (or VRF) in the ACI fabric:

Tenants, VRFs, EPGs, and Endpoints.

Overlay topology of a tenant (or VRF) in the fabric.

Underlay topology of a tenant (or VRF) in the fabric.


1.Click Network on the taskbar.

2.In the Network pane, select Network Centric View > Tenant View. The ACI data model (Multi Site) is organized in this order: Multi Site Folder > Multi Site Orchestrator > APIC Domain > Tenant > VRF > EPG (Endpoint Group) > Endpoint

2.Expand a tenant node to view the relationship between child nodes.

3.Click a VRF node, and then select a context map to view the corresponding structure of this VRF.

Overlay Topology

The overlay topology represents the logical relationship among VRF > Subnet > Endpoint, including:

The connection of this VRF to an external network as well as the relevant external nodes.

The mapping of Bridge Domain (in this VRF) to VLAN and subnet.

Endpoints in an EPG.

The following figure displays the overlay topology of a VRF node.

Underlay Topology

The underlay topology represents the physical resources occupied by a tenant, including:

All IPN nodes in the VRF.

Spine and leaf switches that belong to this VRF.

L3 Out and L2 Out switches in the VRF.

Connectivity of these nodes.

NetBrain currently provides two different underlay structures of a VRF node:

Multi-Pod deployed in a single Data Center (direct IPN connection between multiple Spines)

Multi-Pod deployed across different Data Centers (indirect IPN connection between multiple Spines)

Note: Indirect IPN connection can refer to an L3 Network or MPLS Network.

The following figure shows the underlay structure of direct IPN connection between two Spines.