InJuniper Networks Mist AI Wireless, access points discover upstream switch and port information using Link Layer Discovery Protocol (LLDP). LLDP is an IEEE-standard, vendor-neutral Layer 2 discovery protocol designed specifically to allow network devices to advertise and learn information about directly connected neighbors.
When a Juniper Mist AP connects to a wired switch, it uses LLDP to exchange information such as:
* Switch hostname and chassis ID
* Switch port identifier
* VLAN details
* Power over Ethernet (PoE) capabilities and power allocation
This information is critical for Mist operations and visibility. It enables the Mist cloud to accurately display AP-to-switch mappings, identify theexact switch portan AP is connected to, validate PoE delivery, and assist with troubleshooting wired-side issues that impact wireless performance. LLDP data is also leveraged by Mist AI and Marvis to correlate wired and wireless events, improving root-cause analysis.
The other options are incorrect for the following reasons:
* CDP (Cisco Discovery Protocol)is a Cisco-proprietary protocol and is not used by Juniper Mist APs for switch discovery.
* ARP (Address Resolution Protocol)resolves IP addresses to MAC addresses and does not provide device or port identity information.
* SNMPis a management and monitoring protocol used by controllers or management systems, not by APs for neighbor discovery.
Because LLDP is standards-based, lightweight, and designed for neighbor discovery, it is the correct and supported protocol used by Juniper Mist APs to learn switch information.
Therefore, the correct answer isD. LLDP.