Clos Overview

Extreme Fabric Automation (EFA) manages the life cycle of IP Fabric Clos networks.

EFA offers unique flexibility in supporting 3- and 5-stage Fabric Clos topologies based on a BGP underlay with a BGP or EVPN overlay.

Tenant Network onboarding services are supported on both topologies, allowing you to create connectivity for devices connected to the fabric, such as compute (servers), storage, and connectivity to external routers or gateways.

3-Stage Clos

3-stage Clos consists of an ingress leaf layer, a middle spine layer, and an egress leaf layer. Servers are connected to leaf devices and leaf devices are connected to all spines. No leaf devices are connected to other leaf devices, nor are spines connected to spines. Data enters at an ingress leaf, is routed through a spine to an egress leaf, and then out of the network to the next server in the path. In this topology, servers are always 3 hops (leaf, spine, leaf) away from another server.

A three-stage fabric where Spine 1 and Spine 2 are each configured to Leaf 1, Leaf 2, and Leaf 3

5-Stage Clos

5-stage Clos is a 3-stage topology that is divided into clusters and on which a Super-spine layer is added. All links between leaf and spine must be connected. Spine are not be interconnected. Similarly, all the links between the spine and Super-spine must be connected.

Three device layers from top to bottom: Super-spine, spine, and leaf. All device layers are linked, but individual nodes are not interconnected