The Purpose of a Cisco SD-Access Underlay Network

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Sure, I'd be happy to provide a detailed explanation of the purpose of a Cisco SD-Access underlay network.

In Cisco's Software-Defined Access (SD-Access) architecture, the underlay network provides the physical infrastructure and connectivity between network devices, such as switches and routers. The underlay network forms the foundation of the network and provides the necessary transport to support the overlay network.

The purpose of the underlay network in SD-Access is to abstract IP-based connectivity from physical connectivity, which means that the physical network topology is no longer visible or relevant to network applications and services. This abstraction allows network administrators to manage the network based on logical constructs, such as virtual networks or policies, rather than physical locations or devices.

In addition to abstracting physical connectivity, the underlay network also establishes physical connectivity between switches and routers. This connectivity is essential for the efficient and reliable transport of network traffic between devices, as well as for the creation of virtual networks and policies that are built on top of the underlay.

The underlay network is also responsible for providing virtualization by encapsulating network traffic over IP tunnels. This encapsulation enables the creation of virtual networks, or overlays, that can be used to isolate network traffic and enforce policies that are specific to different types of network traffic. By encapsulating network traffic over IP tunnels, the underlay network also provides additional security and scalability features.

In summary, the purpose of the Cisco SD-Access underlay network is to provide the physical infrastructure and connectivity for the network, abstract IP-based connectivity from physical connectivity, establish physical connectivity between switches and routers, and provide virtualization by encapsulating network traffic over IP tunnels.