Cisco SDA and Cisco DNA Center
Software-Defined Access (SDA) Architecture
SDA uses a controller and application programming interfaces (APIs) to communicate via southbound interfaces (SBIs) with the network infrastructure.
Cisco Digital Network Architecture (DNA) Center is an example of a controller.
SDA Architecture with DNA Center
Fabric:
The network infrastructure, called the fabric, and divided into two parts underlay and overlay .
Switch1 and Switch2, dynamically create a Virtual Extensible LAN (VXLAN) tunnel between the endpoints in the overlay. The exact path the data takes between the two switches is determined by the underlay's Layer 2 and Layer 3 process.
Underlay: The underlay includes the switches, routers, cables, and wireless links used to create the physical network. It also includes the configuration and operation of the underlay to support the work of the overlay network.
The SDA underlay configuration includes different SDA roles filled by each device. These roles include:
- Fabric edge node: A switch that connects to endpoint devices.
- Fabric border node: A switch that connects to devices outside SDA's control, such as switches that connect to the WAN routers.
- Fabric control node: A switch that performs special control plane functions for the underlay, requiring more CPU and memory.
Overlay: Cisco chose the VXLAN protocol to create the tunnels used by SDA. When an SDA endpoint (for example, an end-user computer) sends a data link frame to an SDA edge node, the ingress edge node encapsulates the frame and sends it across a VXLAN tunnel to the egress edge node.
VXLAN Tunneling Protocol Operation:
The VXLAN tunnel in the overlay works like this:
- An endpoint sends a frame.
- The frame is encapsulated in the VXLAN tunneling specification.
- The frame is forwarded to the underlay fabric.
-
The other nodes in the underlay forward the frame based on the VXLAN tunnel
details.
- The last SDA node removes the VXLAN details.
- The frame is forwarded to the destination endpoint.
Cisco DNA Center:
Cisco DNA Center has two roles:
1- A controller in a network that uses Cisco SDA.
2- A network management platform for traditional (non-SDA) network devices.
Cisco DNA Center supports several southbound APIs so that the controller
can communicate with the devices it manages:
- Telnet, SSH, and SNMP to support traditional networking devices
-
NETCONF and RESTCONF to support newer devices
Cisco DNA Center Network Management Platform:
Cisco DNA Center supports basic automation capabilities, fabric provisioning, and policy-based segmentation (SGTs) in the enterprise network.
Cisco DNA Center is a network management and command center for provisioning and configuring network devices.
Cisco DNA Center is a hardware and software platform that provides a “single pane of glass” (also called a dashboard) that focuses on assurance, analytics, and automation.
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