The physical network underlay serves as the transport medium for the software-defined network. Its design and architectural integrity are fundamental to the overall performance of the SDN stack. A problem at this layer can have a disruptive impact on performance. Thankfully, this is where the engineered excellence of the VxBlock 1000 comes into play. Each subcomponent of the physical network layer is highly redundant and is engineered for throughput, scale, and low latency. VxBlock components participating in the NSX-T underlay include the following:
The Physical Underlay has been designed to scale. From the beginning, the modular architecture of the VxBlock platform means that the customer is not assuming the technical debt associated with a monolithic architecture. Given its ‘persistent architecture,’ as the platform evolves, new VxBlock 1000 components can be gracefully integrated into the underlay. These may include physical servers but also network interface cards and Virtual Interface Cards (VICs) that add new hardware offload and security features to the underlay.
The Underlay performs three primary functions. All other use cases depend on a well-designed and scalable underlay:
Clearly this relationship between the technical system and business process did not meet the requirements of the digital revolution in an era in which applications and networks are required ‘on the fly’ for businesses to remain relevant, competitive, and successful.
Figure 8. Scalable architecture
The VxBlock 1000 with NSX-T is designed specifically with scalability in mind. The figure above shows how NSX-T, in combination with the Overlay, can scale in the Data Center by minimizing the failure domain footprint -- in this instance -- per Fabric-Interconnect pair. However, VxBlock 1000 in conjunction with Vscale can scale the NSX-T Data Plane almost infinitely at the ToR layer.
It can scale in this way by introducing a network architecture based upon ‘Spine/Leaf’ versus the traditional 3-Tier Core/Aggregation/Access Architecture. The Spanning Tree Protocol (STP) is eliminated as a Data Plane reachability protocol between failure domains and replaced by Layer 3 protocols such as BGP, BGP-EVPN, and IS-IS. These Layer 3 protocols are much more efficient for managing control and data plane reachability information and eliminate the use of STP between failure domains. For a deeper overview of the VxBlock architecture see Dell EMC VxBlock™ System 1000 Architecture Overview.