The Layer 3 Leaf and Spine design is becoming the more adopted design for newer, more modern data center fabrics depicted in figure 30.

Figure 30.          Leaf and Spine Layer 3 Design

It has the following characteristics:

• L3 is terminated at the leaf, thus all the VLANs originating from ESXi hosts terminate on leaf.
• The same VLANs can be reused for each rack.
• The leaf switches provide default gateway functionality.
• The NSX-V ESGs or NSX-T T0 Gateway for the WLD will peer with the leaf switches in each rack.

Advantages:

• Vendor agnostic - Multiple network hardware vendors can be used in the design.
• Reduced VLAN span across racks, thus smaller broadcast domains.
• EastWest for an NSX domain can be confined within a rack with intra-rack routing at the leaf.
• EastWest across NSX domains or Cross-Rack are routed through the Spine.
• ESG peering is simplified by peering the WLDs with the leaf switches in the rack.

Disadvantages:

• The Layer 2 VLANs cannot span racks. Clusters that span racks will require a solution to allow VxRail system traffic to span racks using hardware VTEPs.
• The Layer 3 configuration might be more complex to implement.