♦Aironet 1000 Series Lightweight APs
♦Aironet 1100 Series APs
♦Aironet 1130 AG Series
♦Aironet 1140 AG Series
♦Aironet 1200 Series
♦Aironet 1230 AG Series
♦Aironet 1240 AG Series
♦Aironet 1250 AG Series
♦Aironet 1300 Series Access Point/ Bridges Power Injector
♦Aironet 1400 Series Bridge
♦Aironet 1500 Series APs
∙All models of the WLC in these series:
♦Cisco 2000 Series WLCs
♦Cisco 2100 Series WLCs
♦Cisco 4100 Series and 4400 Series WLCs
♦Cisco 5500 Series WLCs
The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.
Conventions
Refer to Cisco Technical Tips Conventions for more information on document conventions.
Cisco Discovery Protocol
Cisco Discovery Protocol is a device discovery protocol that runs on all Cisco−manufactured equipment, such as routers, bridges, and communication servers. Each device sends periodic messages to a multicast address and listens to the messages that others send in order to learn about neighboring devices. When the Aironet device boots, it sends a CDP packet with the information that the device is inline power−enabled. Then, the switch, or a comparable device, can supply the requested power.
The Cisco Aironet APs support local power as well as Power over Ethernet (PoE), either by an IEEE 802.3af−compliant Power Sourcing Equipment (PSE) device, such as a switch, or by a device capable that provides the required power and compliant with Cisco Inline Power. This does not affect the performance or range of the AP in any way.
The AP disables the radio interfaces when the unit senses that the power source to which it is connected does not provide enough power. It is possible, due to the power source, that you need to enter the power source type in the access point configuration.
If Cisco CDP is enabled, the AP tries to negotiate with the use of CDP. If CDP tells the AP that it cannot supply the power, the unit shuts down the radios. CDP is enabled on the Ethernet port of the APs by default. But, CDP is enabled on the radio port of the access points only when the radio is associated to another wireless infrastructure device, such as an access point or a bridge.
If you want to use a power injector to supply power to an AP and if POE is also available in the network, disable CDP on that port so that the AP draws power from the Power injector.