158 Power over Ethernet• a device is connected to port 41 and requests powerIn this scenario, the Nortel Ethernet Routing Switch 4548GT-PWR providespower to the device on port 41 because that port is configured as highpriority. However, to maintain the power budget, the switch drops one ofthe ports configured as low priority. As all the other ports (1 to 40) areconfigured with a low priority, the switch drops power to the highest portnumber. In this case, the switch drops power to port 40 and provides powerto port 41. If another port drops power, the switch automatically reinstatespower to port 40.You configure the autodiscovery power process as either IEEE802.3af-compliant or IEEE 802.3af-draft-compliant and legacy:• 802.3af: detection method described in the IEEE 802.3af draft standard• legacy: detection standard in use prior to the IEEE 802.3af draftstandardThe default value is IEEE 802.3af-draft-compliant. You can set thisparameter for the entire switch; you cannot set the discovery mode for eachport.You can obtain power usage information from the management systems.Statistics do not accumulate. The system automatically disconnects the portfrom power when it detects an overload on any port, and the remainder ofthe ports remain functional.Note: Ensure that you set the switch for the power- detection mode usedby the connected powered device. Consult the device documentationfor this information.Configuring PoE using the CLIThe following section describes the commands necessary to configure PoEusing the CLI:• "Set port power enable or disable" (page 159)• "Set port power priority" (page 159)• "Set power limit for channels" (page 159)• "Set traps control" (page 160)• "Show main power status" (page 160)• "Set power usage threshold" (page 160)• "Setting PoE detection method" (page 161)• "Show port power status" (page 161)• "Show port power measurement" (page 161)Nortel Ethernet Routing Switch 4500 SeriesOverview — System ConfigurationNN47205-500 02.01 Standard5.0 23 February 2007Copyright © 2007, Nortel Networks Nortel Networks Confidential.
