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Zorluk: Çok zorSoftware-Defined Architectures: Overlay, Underlay, and Fabric

In Cisco Software-Defined Access (SD-Access) architectures, clear functional boundary separation exists between the underlay, overlay, control plane, and data plane components. Match each SDN fabric component or protocol on the left with its correct primary architectural role or operational mechanism on the right.

  • Locator/ID Separation Protocol (LISP)Functions as the overlay control plane by tracking Endpoint Identifier (EID) to Routing Locator (RLOC) mappings.
  • Virtual Extensible LAN (VXLAN)Functions as the overlay data plane by encapsulating original Layer 2 frames into UDP packets destined for remote VTEP IP addresses.
  • Underlay Routing InfrastructureEstablishes physical topology connectivity and IP reachability between fabric switches using an Interior Gateway Protocol (IGP).
  • Fabric Edge NodeAuthenticates host endpoints, attaches them to the fabric, and updates the control plane database with endpoint location information.

Cevap

Locator/ID Separation Protocol (LISP) matches with tracking EID-to-RLOC mappings in the overlay control plane. Virtual Extensible LAN (VXLAN) matches with encapsulating original Layer 2 frames in UDP headers for data plane transport. Underlay Routing Infrastructure matches with establishing physical topology connectivity and IP reachability using an IGP. Fabric Edge Node matches with authenticating endpoints and updating the control plane mapping database.
Each component is mapped accurately according to Cisco SD-Access fabric architecture definitions: LISP manages EID-to-RLOC control plane resolution; VXLAN handles data plane encapsulation; the underlay IGP ensures physical node reachability; and the Fabric Edge Node authenticates end hosts and connects them to the fabric.

Adım Adım Çözüm

1
Identify the primary function of Locator/ID Separation Protocol (LISP) within SDN fabric architecture.
LISP separates an endpoint's identity (EID) from its network location (RLOC) and operates as the control plane to map host locations.
Control plane operations track where endpoints reside without broadcasting MAC addresses throughout the physical core.
2
Determine the role of Virtual Extensible LAN (VXLAN).
VXLAN encapsulates Layer 2 ethernet frames inside UDP packets (destination port 4789) for overlay data plane transport.
VXLAN provides virtualized Layer 2 and Layer 3 overlay transport across an IP underlay without requiring Layer 2 stretching in the physical infrastructure.
3
Analyze the responsibility of the Underlay Routing Infrastructure.
The underlay provides hop-by-hop physical IP transport using IGP protocols like IS-IS or OSPF.
Overlay tunnel endpoints (VTEPs / RLOCs) rely strictly on underlay IP reachability to exchange encapsulated traffic.
4
Evaluate the operational scope of the Fabric Edge Node.
The Fabric Edge Node connects end devices, handles client onboarding/security, and registers host EIDs with the LISP Control Plane Node.
Edge nodes function as the entry point into the SD-Access fabric for user traffic and telemetry.

Anahtar Kavram

Software-Defined Architecture Roles: Overlay, Underlay, Control Plane (LISP), and Data Plane (VXLAN)
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Software-Defined Architectures: Overlay, Underlay, and Fabric

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