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Zorluk: OrtaSoftware-Defined Architectures: Overlay, Underlay, and Fabric

A network administrator is implementing a Cisco Software-Defined Access (SD-Access) architecture across an enterprise network campus. Which two operational characteristics are specific functions of the fabric overlay network rather than the underlay network? (Select two.)

  1. Encapsulating user data traffic into VXLAN packets to maintain logical Layer 2 and Layer 3 virtual network boundaries across the fabric.Cevap
  2. Maintaining a control plane mapping database using LISP to map endpoint identifiers to their current routing locator addresses.Cevap
  3. C
    Establishing IP connectivity and IGP routing reachability between intermediate fabric switch interfaces using OSPF or IS-IS.
  4. D
    Executing agentless configuration playbooks over SSH to automate initial physical switch hardware provisioning.
  5. E
    Sending HTTP POST requests via REST APIs to retrieve operational status and interface state from network devices.

Cevap

The two correct overlay functions are encapsulating user data traffic into VXLAN packets to maintain logical network boundaries, and using LISP to map endpoint identifiers (EIDs) to routing locators (RLOCs).
In software-defined architectures (such as Cisco SD-Access), the overlay network creates logical virtual networks over the physical topology. The data plane uses VXLAN encapsulation to carry Layer 2 Ethernet frames and Layer 3 IP packets wrapped in UDP headers between fabric nodes. The control plane uses LISP (Locator/ID Separation Protocol) to manage the mapping database connecting Endpoint Identifiers (EIDs) to Routing Locators (RLOCs).

Adım Adım Çözüm

1
Differentiate between the roles of underlay and overlay networks in an SDN fabric architecture.
The underlay provides physical interconnectivity and routing reachability between fabric nodes (RLOCs), while the overlay builds virtual networks on top of the underlay.
Clear layer separation is required to identify which protocols and mechanisms belong to the overlay layer.
2
Identify the data plane and control plane encapsulation mechanisms used by the SD-Access overlay.
VXLAN provides Layer 2 and Layer 3 overlay data plane encapsulation, and LISP provides overlay control plane location/identity separation mapping.
VXLAN and LISP are the defining overlay protocols in Cisco SD-Access.

Anahtar Kavram

Overlay vs. Underlay Roles in SDN Fabrics
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Konular

Software-Defined Architectures: Overlay, Underlay, and Fabric

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