Purpose of LLDP in Power Control
Link Layer Discovery Protocol (LLDP) is a standard-based protocol for power control in APs. LLDP uses the type–length–value (TLV) format to exchange information. Organizations can define and encode their own TLVs, which are called Organizationally Specific TLVs.
LLDP can be used to negotiate power values between a network switch and a device and interact with PoE to determine whether there is enough power to meet the device’s request.
The main motivation for implementing LLDP is to improve power management for Celona APs, such as AP20 and AP22 connected to PoE switches. By design, these APs request the maximum power at startup—90W requested, 71W delivered—due to hardware-level signaling. However, in many instances, the access points do not require that much power for normal operation.
Some PoE switches will not grant this high-power request unless LLDP signaling is active. In deployment environments without LLDP, APs have been capped at delivering only 30W of power. LLDP, as defined by the IEEE 802.3at standard, fine tunes the power request dynamically after the hardware has booted, ensuring that the AP gets the appropriate amount of power based on its requirements. While IEEE 802.3bt adds hardware-level power negotiation, AP20 and AP22 only utilize LLDP signaling post boot to request fine tuned power.
Platform Requirements
LLDP is supported on the following APs:
AP20, AP21, and AP22 models
Future AP 2x platforms
To use LLDP, the following are the minimum software versions required:
Celona Orchestrator: 2406.1
Celona Edge Clusters: 2406.edge.0.2-1
Celona Access Points: 2406.ap.0.3-1
PoE and LLDP
To fully understand the significance of LLDP in the context of PoE, it’s helpful to review the basics of PoE technology. Power over Ethernet (PoE) allows APs to be powered directly from the network switch without requiring separate power sources. PoE devices fall into two categories:
Powered Devices (PDs), such as Celona APs
Power Sourcing Equipment (PSE), typically network switches or PoE injectors
PSEs come in two types:
Endpoint PSEs such as a PoE-capable network switch
Midspan PSEs, also called injectors
PoE standards have evolved, with 802.3af, 802.3at, and 802.3bt expanding power delivery capabilities to support higher-powered devices. For example, 802.3af supports up to 15.4W of power, while 802.3at (PoE+) delivers up to 25.5W. The latest standard, 802.3bt, enables up to 90W of power delivery, making it ideal for high-power devices like Celona APs.
Benefits of LLDP in Network Visibility and Troubleshooting
In addition to power management, LLDP enhances network visibility and troubleshooting. By enabling LLDP, Celona APs periodically exchange information with connected switches. This allows customers to see detailed information about peer switches, such as their identity and capabilities. LLDP provides the following key advantages:
Peer Switch Visibility: LLDP allows administrators to discover connected switches and view their details, making monitoring and managing network equipment easier.
Troubleshooting: LLDP data helps troubleshoot network issues by providing detailed information on the switch to which an AP is connected.
Interoperability: LLDP is a standardized protocol that functions similarly to proprietary protocols like Cisco’s Discovery Protocol (CDP) but with greater flexibility and cross-vendor compatibility.
Current LLDP Behavior in Celona APs
To ensure minimal disruption, LLDP is not automatically enabled on existing APs. Customers must manually enable LLDP for those devices. However, for new APs added after the 2406.1 CSO release, LLDP is enabled by default.
Administrators can manage LLDP settings through the Celona Orchestrator UI. The UI displays LLDP data, including telemetry about LLDP neighbors, for easier monitoring and management.
Steps to Enable LLDP on the Celona Orchestrator UI
LLDP settings can be configured easily through the CSO with just a few steps:
Navigate to the Access Points page of the Celona Orchestrator.
Select the relevant AP and click on the Summary tab.
Note: Starting with Celona Orchestrator (CSO) release 2411, the Config tab has been renamed and reordered as the Summary tab.Scroll down to Advanced Access Point Config for that AP.
Using the toggle button, enable the LLDP.
Click on LLDP to view the LLDP Neighbor list.
Click on the row to see more telemetry data about LLDP neighbors.
