Dell PowerConnect 55xx Systems User Guide 379OverviewThis section includes a description of port features and describes thefollowing:• Auto-Negotiation• MDI/MDIX• Flow Control• Back Pressure• Port Default SettingsAuto-NegotiationAuto-negotiation enables automatic detection of speed, duplex mode andflow control on all switching 10/100/1000BaseT ports. Auto-negotiation isenabled on all ports by default.Auto-negotiation is a mechanism established between two link partners toenable a port to advertise its transmission rate, duplex mode and flow controlabilities to its partner. Both ports then operate at the highest commondenominator.If connecting a Network Interface Card (NIC) that does not support auto-negotiation or is not set to auto-negotiation, both the device switching portand the NIC must be manually set to the same speed and duplex mode.If the station, on the other side of the link, attempts to auto-negotiate with adevice 100BaseT port that is configured to full duplex, the auto-negotiationresults in the station attempting to operate in half duplex.MDI/MDIXThe device supports auto-detection of straight-through and crossed cables onall 10/100/1000BaseT ports. This feature is part of auto-negotiation and isenabled when Auto-negotiation is enabled.When the MDI/MDIX (Media Dependent Interface with Crossover) isenabled, the automatic correction of errors in cable selection is possible, thusmaking the distinction between a straight-through cable and a crossover cable
