Control Plane – vSmart is the Controller in Viptela solution and manages the Control Plane.

vSmart does all the complex work of path calculation, route advertisement etc. there by offloading the Data Plane to do only packet forwarding.

B is correct. Within a Cisco SD-Access fabric, authentication is NOT simply Radius but uses ISE to grant or deny full access.

Identity services: Cisco Identity Services Engine (ISE) identifies users and devices connecting to the network and provides the contextual information required for users and devices to implement security policies for network access control and network segmentation.

Cloud can be scaled up or down and in and out if the load requires it.

vSmart functions:

1. vSmart is the brain of the entire system.

2. Works with vBond to authenticate Viptela devices as they join the network.

3. Builds Control Plane connections with vEdge using TLS.

4. Orchestrate connectivity between vEdges via the policies there by creating the network topology.

5. Acts as a Route reflector by advertising the branches prefixes based on the policy.

6. Shares the data plane keys of a vEdge with other vEdges based on the policy to allow them to build the tunnels – IKEless IPSEC.

7. Policies are configured on vSmart.

Fabric wireless controllers manage and control the fabric-mode APs using the same general model as the traditional local-mode controllers which offers the same operational advantages such as mobility control and radio resource management.

A significant difference is that client traffic from wireless endpoints is not tunneled from the APs to the wireless controller. Instead, communication from wireless clients is encapsulated in VXLAN by the fabric APs which build a tunnel to their first-hop fabric edge node.

Wireless traffic it tunneled to the edge nodes as the edge nodes provide fabric services such as the Layer 3 Anycast Gateway, policy, and traffic enforcement.

https://www.cisco.com/c/en/us/td/docs/solutions/CVD/Campus/cisco-sda-design-guide.html

D - FIB is NOT a list of routes to a particular network, it has a list of all the best routes to get to all reachable networks.

RIB --> All the routing entry should be present in Routing Information Base(RIB) best path and second path ...

FIB --> only best path should be present in the Forwarding Information Base(FIB).

An overlay network creates a LOGICAL topology used to virtually connect devices that are built over an arbitrary physical underlay topology.

An overlay network is created on top of the underlay network through virtualization (virtual networks). The data plane traffic and control plane signaling are contained within each virtualized network, maintaining isolation among the networks and an independence from the underlay network.

SD-Access allows for the extension of Layer 2 and Layer 3 connectivity across the overlay through the services provided by through LISP.

=> D is correct.

-Punted packets are packets that can't be CEF switched and has to be process-switched by the CPU.

-CEF switching (or Cisco Express Forwarding) is a proactive, deterministic IP forwarding mechanism.

Routing table (RIB) as computed by routing protocols is copied into forwarding table (FIB), where it’s combined with adjacency information (ARP or ND table) to form a deterministic lookup table.

Against failure due to the Supervisor or loss of service because of software problems. The access layer typically provides Layer 2 services with redundant switches making up the distribution layer. The Layer 2 access layer can benefit from SSO deployed without NSF. Some Enterprises have deployed Layer 3 routing at the access layer. In that case, NSF/SSO can be used.

=> A,C is correct.