When is it advisable to provide dedicated control plane nodes within a Cisco SD-Access design?

In small deployments, control plane functionality can often be collapsed onto border nodes, making dedicated control plane nodes unnecessary.

Dedicated control plane nodes, such as a Cisco Catalyst 9000 Series switch or a Cisco ISR 4000 Series router, are recommended in larger Cisco SD-Access deployments, especially when there's a requirement for frequent roaming of endpoints across different fabric edge nodes. This is because the control plane node maintains the Host Tracking Database (HTDB) and handles endpoint registration and lookup requests, providing efficient mobility for users as they move within the fabric.

Cisco DNA Center is the management and automation platform for SD-Access; its presence or absence does not dictate the need for dedicated control plane nodes, which are a data plane/control plane function.

Fabric edge nodes are designed to provide control plane functionality in a collapsed role for smaller deployments; the inability to provide this functionality is not a standard design consideration but rather a misconfiguration or a specific hardware limitation not generally assumed.