CCNP ENCOR level SD-WAN interview questions

  1. What is SD-WAN and how does it differ from traditional WAN?
  • SD-WAN stands for Software-Defined Wide Area Network. It is a technology that simplifies the management and operation of a wide area network by separating the control plane from the data plane. Unlike traditional WAN, SD-WAN allows for centralized management, dynamic traffic routing, and improved application performance.
  1. What are the key benefits of implementing SD-WAN in an enterprise network?
  • Some key benefits of implementing SD-WAN include:
    • Enhanced application performance through dynamic traffic routing and optimization.
    • Cost savings by utilizing multiple transport options, such as MPLS, internet, or 4G/5G.
    • Improved network agility and scalability.
    • Simplified network management through centralized control and automation.
    • Enhanced security with built-in encryption and segmentation.
  1. Explain the concept of control plane and data plane separation in SD-WAN.
  • In SD-WAN, control plane and data plane are separated to enable centralized control and dynamic traffic routing. The control plane is responsible for making intelligent routing decisions based on policies defined by the network administrator. It communicates with the data plane, which handles the actual forwarding of traffic based on the routing decisions made by the control plane.
  1. What are the different components of an SD-WAN architecture?
  • The key components of an SD-WAN architecture are:
    • vManage: The network management platform for configuration, monitoring, and troubleshooting.
    • vEdge: The edge router that connects the enterprise network to the SD-WAN overlay network.
    • vSmart: The centralized brain of the network that makes routing decisions based on policies.
    • vBond: The orchestrator responsible for authenticating and authorizing vEdge routers to join the overlay network.
  1. How does SD-WAN provide improved application performance and user experience?
  • SD-WAN improves application performance and user experience through various techniques such as:
    • Dynamic path selection: It selects the optimal path for each application based on real-time network conditions.
    • Traffic prioritization: It prioritizes critical applications over less important ones to ensure better performance.
    • Traffic optimization: It optimizes traffic by deduplicating, compressing, and caching data to reduce latency and bandwidth consumption.
    • Seamless failover: It provides automatic failover to alternate paths in case of link failures to minimize disruption.
  1. What are the different deployment options for SD-WAN?
  • SD-WAN can be deployed in different ways:
    • Hybrid deployment: Combining multiple transport options such as MPLS, internet, or 4G/5G connectivity.
    • Internet-only deployment: Using public internet connections as the primary transport mechanism.
    • On-premises or cloud-based deployment: Deploying SD-WAN appliances either on-premises or in a cloud environment.
  1. Explain the role of vManage in an SD-WAN deployment.
  • vManage is the network management platform in an SD-WAN deployment. Its role includes:
    • Configuration management of SD-WAN devices.
    • Monitoring network health and performance.
    • Troubleshooting network issues.
    • Defining policies for traffic routing, application prioritization, and security.
  1. How does vEdge router establish secure connectivity with the SD-WAN overlay network?
  • vEdge routers establish secure connectivity with the SD-WAN overlay network through secure DTLS (Datagram Transport Layer Security) tunnels. These tunnels provide encryption and authentication to ensure secure communication between vEdge routers and other components of the SD-WAN architecture.
  1. What is the purpose of vSmart router in SD-WAN architecture?
  • vSmart router acts as the central brain of the SD-WAN architecture. Its purpose is to make intelligent routing decisions based on policies defined in vManage. vSmart routers communicate with vEdge routers to exchange routing information and enforce policies throughout the SD-WAN deployment.
  1. How does vBond play a role in authentication and authorization of vEdge routers?
  • vBond acts as the orchestrator in SD-WAN deployments. Its role is to authenticate and authorize vEdge routers to join the SD-WAN overlay network. It provides a secure control plane for establishing trust between vEdge routers and other components of the SD-WAN architecture.
  1. Explain the concept of overlay and underlay network in SD-WAN.
  • In SD-WAN, the overlay network refers to the virtual network created on top of the underlying physical network infrastructure (underlay network). The overlay network is responsible for encapsulating and transporting data packets between different locations in a secure and optimized manner, while the underlay network provides the physical connectivity between devices.
  1. What are the various types of traffic steering techniques used in SD-WAN?
  • Some common traffic steering techniques used in SD-WAN include:
    • Dynamic path selection: Selecting the best path based on real-time network conditions.
    • Application-based steering: Directing specific applications or traffic types over specific paths based on policies.
    • Performance-based steering: Routing traffic based on performance metrics such as latency, packet loss, or jitter.
    • Policy-based steering: Applying user-defined policies to determine how traffic should be routed.
  1. What is Zero Touch Provisioning (ZTP) and how does it simplify the deployment of SD-WAN?
  • Zero Touch Provisioning (ZTP) is a deployment method that allows for automatic provisioning and configuration of SD-WAN devices without manual intervention. ZTP simplifies the deployment process by reducing human errors, saving time, and ensuring consistency across devices.
  1. How does SD-WAN handle link failures and provide seamless failover?
  • SD-WAN handles link failures by continuously monitoring link health and automatically rerouting traffic in case of failures. It uses techniques like dynamic path selection and link monitoring to detect failures and provide seamless failover to alternate paths, ensuring uninterrupted connectivity.
  1. Explain the concept of dynamic path selection and how it optimizes traffic routing in SD-WAN.
  • Dynamic path selection is a key feature of SD-WAN that selects the optimal path for each application or traffic flow based on real-time network conditions. It considers factors such as link quality, latency, jitter, and congestion to determine the best path to ensure optimal performance and user experience.

These answers should provide a good understanding of CCNP ENCOR level SD-WAN concepts. Remember to elaborate on each answer using relevant examples or real-world scenarios during your interview.