The question asks which switch type is discovered first in the Cisco ACI fabric discovery process. The ACI fabric consists of spine and leaf switches, and the discovery process is a critical initial step to establish the fabric topology. Let’s analyze this based on Cisco ACI documentation.
Requirement Analysis
The ACI fabric discovery process involves the Application Policy Infrastructure Controller (APIC) identifying and registering switches to form the network topology.
The process relies on protocols like Link Layer Discovery Protocol (LLDP) and Cisco Discovery Protocol (CDP) to detect connected devices.
The sequence of discovery is determined by the physical connectivity and the role of switches in the fabric.
Option Evaluation
A. leaf:
In the Cisco ACI fabric, the discovery process begins with the leaf switches. When the APIC is powered on and connected to the fabric, it first discovers the leaf switches directly attached to it or other initial points of connectivity. Leaf switches are the access layer devices that connect endpoints and are the starting point for fabric topology discovery. Once leaf switches are identified, they assist in discovering the spine switches.
[: Cisco APIC Installation and Setup Guide, "Fabric Discovery Process" and Cisco ACI Fabric Fundamentals, "Switch Discovery.", B. access: , "Access" is not a specific switch type in the ACI fabric context. It may refer to external access switches, but these are not part of the initial fabric discovery process, which focuses on spine and leaf switches., Reference: Not applicable to ACI fabric discovery., C. distribution: , "Distribution" is a traditional network layer, but it does not apply to the ACI fabric, which uses a spine-leaf architecture. This option is irrelevant., Reference: Not applicable to ACI., D. spine: , Spine switches are discovered after the leaf switches because the leaf switches provide the connectivity path to the spines. The APIC uses the leaf switches to map the spine layer in the fabric topology., Reference: Cisco ACI Architecture White Paper, "Spine-Leaf Discovery Sequence.", Final Answer Justification, A is correct because the ACI fabric discovery process starts with the leaf switches. The APIC initially detects leaf switches connected to it or other initial points, and then uses this information to discover the spine switches, establishing the full fabric topology., Primary Cisco References: , Cisco APIC Getting Started Guide, "Fabric Bring-Up and Discovery.", Cisco ACI Design Guide, "Fabric Discovery Process.", ]
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