Dell PowerConnect 55xx Systems User Guide 17FILE LOCATION: C:\Users\gina\Desktop\Checkout_new\Maintenance Projects\DellContax\sources\CxUGFeatures.fmD E L L C O N F I D E N T I A L – P R E L I M I N A R Y 1 0 / 3 0 / 1 3 - F O R P R O O F O N LY• IP Gateways• PDAs• Audio and video remote monitoringFor more information, see "Power over Ethernet" on page 162.Green EthernetGreen Ethernet, also known as Energy Efficient Ethernet (EEE), is an effortto make networking equipment environmentally friendly, by reducing thepower usage of Ethernet connections.The Short-Reach method, which reduces power over Ethernet cables shorterthan 40m, is supported by the device.For more information, see "Green Ethernet Configuration" on page 391.Head of Line Blocking PreventionHead of Line (HOL) blocking results in traffic delays and frame loss causedby traffic competing for the same egress port resources. To prevent HOLblocking, the device queues packets, and packets at the head of the queue areforwarded before packets at the end of the queue.Flow Control Support (IEEE 802.3X)Flow control enables lower-speed devices to communicate with higher-speeddevices, by requesting that the higher-speed device refrain from sendingpackets. Transmissions are temporarily halted to prevent buffer overflows.For more information, see "Flow Control" on page 387.Back Pressure SupportOn half-duplex links, the receiving port prevents buffer overflows byoccupying the link so that it is unavailable for additional traffic.For more information, see "Protected Ports" on page 395.
