The Concept of Cisco ACI Remote Leaf

Cisco comes up with the concept called Cisco ACI Remote Leaf. As we discussed about Cisco ACI in our earlier articles like Cisco Pod, Cisco Stretched Fabric, Cisco ACI Multipod and Cisco ACI Multisite.

Cisco ACI Release 1.0
Starting with Cisco ACI concept, Cisco comes up with Cisco ACI Release 1.0 which defines a classic leaf-and-spine two-tier fabric (a single Pod) in which all the deployed leaf nodes are fully meshed with all the deployed spine nodes.

Cisco ACI Release 2.0
Well now the issue is to extend the network to the other datacenter. Cisco ACI Release 2.0 introduced the Cisco ACI Multipod architecture. This model calls for the deployment of separate Cisco ACI Pods, each running separate instances of control-plane protocols and interconnected through an external IP routed network via interpod network.

Cisco ACI Release 3.0
Cisco Multipod is a success story for various customers but now the demand is the need for complete isolation across separate Cisco ACI networks by which Cisco comes up with the Cisco Multisite design which is basically a Cisco ACI Release 3.0.

Cisco ACI Multi-Site offers connectivity between the two completely separate ACI fabrics (Sites) that are managed by a Multisite Orchestrator (MSO). Each ACI fabric has an independent APIC cluster, and control plane to provide complete fault isolation.
BGP EVPN is used to exchange control plane information and VXLAN is used for data-plane communication between ACI Sites and to extend the policy domain by carrying to policy information in the VXLAN header

 If you want to understand about the above terminology first, then go with the below link to understand more about that

Cisco ACI Remote Leaf
With the high cost of the Cisco Multisite and Multipod environments and the demand of the customers for the new innovation in the Cisco ACI environment, Cisco comes up with the concept of ACI remote leaf. With the help of remote leaf, Cisco delivers multiple business values since it can manage remote DCs without investing into APIC controllers and Spine switches at remote Locations. This means for the remote location where you have the servers (Bare metals or virtual) can only take leaf switches and will be connected to the spine via IP WAN network which is physically on the other location.

Fig 1.1- Cisco ACI Remote Leaf design

So simply it means you have a site A and the Datacenter 1. So site Datacenter 1 has full architecture of Cisco ACI which consists of Cisco Spine and Leaf and for outside connectivity there is a WAN router. While on the other hand Site A has two servers and we can connect the servers with the Leaf switches and then to the WAN router at the Site A which further connects to the WAN router of the datacenter 1 and can be controlled via same APIC which is used in the Datacenter 1.

Purpose it solves
Extension of the ACI policy model outside the main datacenter to remote sites distributed over IP backbone and extension of ACI fabric to a small DC without investing in full-blown ACI Fabric.
Centralized policy management and control plane for remote locations and small form factor solution at locations with space constraints

In the next article, we will going to discuss about the Cisco ACI 4.0 vPod concept and Cisco ACI over the cloud.