Cisco WS-X6K-SUP1A-2GE Software Guide - Page 829

Chapter 44 Configuring a VoIP Network Configuring VoIP on a Switch These sections provide information related to IP phone power requirements and management: • Unpowered Phone, page 44-13 • Power Requirements, page 44-13 • Wall-Powered Phones, page 44-13 • Powering Off the Phone, page 44-14 • Phone Removal, page 44-14 • High-Availability Support, page 44-14 Unpowered Phone When an unpowered phone is discovered on a switching module port, the switching module reports to the supervisor engine that an unpowered phone is present and on which module/port. If the port is configured in Auto mode, the supervisor engine determines if there is enough available system power to allow the switching module to power up and run the phone. If there is sufficient power, the supervisor engine removes the default allocated power required by a phone from the total available system power and then sends a message to the switching module instructing it to provide power to the port. If there is not enough available power for the phone, the supervisor engine sends a message to the switching module indicating that power is denied to the port. After power is applied to the port, the supervisor engine monitors the port to ensure that the link comes up. If the link does not come up within 4 seconds, the supervisor engine instructs the switching module to turn power off. The entire cycle is repeated, and the switching module performs discovery and reports to the supervisor engine if a device is present on the port. Power Requirements IP Phones may have different power requirements. The supervisor engine initially allocates the configured default of 7W (167 mA at 42V) to the Cisco IP Phone. When the correct amount of power is determined from the CDP messaging with the Cisco IP Phone, the supervisor engine reduces or increases the allocated power. For example, the default allocated power is 7W. A Cisco IP Phone requiring 6.3W is plugged into a port. The supervisor engine allocates 7W for the Cisco IP Phone and powers it up. Once the Cisco IP Phone is operational, it sends a CDP message with the actual power requirement to the supervisor engine. The supervisor engine then decreases the allocated power to the required amount. Wall-Powered Phones When a wall-powered phone is present on a switching module port, the switching module cannot detect its presence. The supervisor engine discovers the phone through CDP messaging with the port. If the phone supports inline power (the supervisor engine determines this through CDP), and the mode is set to Auto or Off, the supervisor engine does not attempt to power on the port. If a power outage occurs, and the mode is set to Auto, the phone loses power, but the switching module discovers the phone and informs the supervisor engine, which then applies inline power to the phone. 78-13315-02 Catalyst 6000 Family Software Configuration Guide-Releases 6.3 and 6.4 44-13