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Difficulty: EasySoftware-Defined Architectures: Overlay, Underlay, and Fabric

Match each Software-Defined Networking (SDN) architectural component or layer on the left with its primary function on the right.

  • Underlay NetworkProvides physical Layer 3 IP reachability and transport using routed protocols.
  • Overlay NetworkCreates virtual logical tunnels (such as VXLAN) to encapsulate host traffic.
  • Fabric Control PlaneTracks location mappings between Endpoint Identifiers (EIDs) and Routing Locators (RLOCs).
  • Network FabricIntegrates underlay, overlay, and control plane protocols into a unified automated network system.

Answer

Underlay Network matches with providing physical Layer 3 IP reachability; Overlay Network matches with creating virtual logical tunnels to encapsulate host traffic; Fabric Control Plane matches with tracking location mappings between EIDs and RLOCs; Network Fabric matches with integrating underlay, overlay, and control plane protocols into a unified network system.
Each architectural layer serves a specific distinct function: the underlay delivers physical Layer 3 IP reachability, the overlay handles logical encapsulation tunnels (such as VXLAN), the fabric control plane manages host location mapping (EID to RLOC via LISP), and the fabric refers to the integrated end-to-end software-defined solution.

Step-by-Step Solution

1
Identify the role of physical IP infrastructure in software-defined architectures.
The underlay network provides basic Layer 3 unicast routing and physical IP reachability across all fabric nodes.
Overlay encapsulation protocols rely on underlying IP reachability between tunnel endpoints.
2
Determine the encapsulation and virtualization layer.
The overlay network uses tunneling protocols such as VXLAN to create logical topologies over the physical underlay.
Overlays abstract tenant network services from the underlying physical cabling and routing topology.
3
Associate control plane functions with endpoint location tracking.
The control plane protocol (e.g., LISP) maps Endpoint Identifiers (EIDs) to Routing Locators (RLOCs).
Decoupling endpoint identity from physical location enables mobility and simplified policy enforcement within the fabric.
4
Define the overarching fabric structure.
The network fabric is the combined system encompassing underlay, overlay, and control plane elements.
Together, these elements form the unified software-defined architectural ecosystem.

Key Concept

Software-Defined Architecture Components: Underlay, Overlay, Control Plane, and Fabric
Estimated Time:45s
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Topics

Software-Defined Architectures: Overlay, Underlay, and Fabric

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