Building a VirtualWire™ Fabric

Multiple VirtualWire switches can be interconnected to form a single VirtualWire fabric. A VirtualWire fabric is like a highly scalable and distributed patch panel that can be dynamically and remotely provisioned to implement single dedicated wire speed links between any two device ports in the network.

When all of the switches in the VirtualWire fabric are part of the same Management Fabric, they can be provisioned and controlled as a single logical VirtualWire switch.

The most efficient design for a VirtualWire fabric is based on the classic leaf-spine architecture, or Clos, a non-blocking, multistage switching topology, as in the figure below.

Figure 1-7 - Leaf and Spine Topology for Virtual Wire Fabric

Note: In CLOS architecture, there is no limit to the number of VirtualWire links between device ports that are physically connected to the same leaf. Instead, the number of VirtualWire links between device ports that are connected to different leafs depend on the over-subscription ratio between leaf and spine.

With this approach, you can select the desired over-subscription ratio and build a modular and scalable architecture to scale up to thousands of device ports.

For example, using the Dell or Freedom series switches as building blocks, a possible leaf switch configuration uses 48 X 10 Gigabit Ethernet ports to connect to device ports and 6 x 40 Gigabit Ethernet ports to connect to the spine layer, resulting in a 1.8:1 over-subscription ratio.

Based on the desired maximum number of device ports, you can select from different scale options:

17 leaf 6 spine at 1.8:1 over-subscription ratio for a total of 748 device 10 Gbps/1Gbps ports

Figure 1-8:  17 Leafs and 6 Spines

34 leaf 12 spine at 1.8:1 over-subscription ratio for a total of 1496 device 10Gbps/1Gbps ports

Figure 1-9: 34  Leafs and 12 Spines

68 leaf 24 spine at 1.8:1 over-subscription ratio for a total of 2992 device 10Gbps/1Gbps ports

Figure 1-10 -  68 Leafs and 24 Spines