Port Default Settings

The general information for configuring the device ports includes the short description of the auto-negotiation mechanism and the default settings for switching ports.

Auto-Negotiation

Auto-negotiation enables automatic detection of speed, duplex mode and flow control on all switching 10/100/1000BaseT ports. Auto-negotiation is enabled per port by default.

Auto-negotiation is a mechanism established between two link partners to enable a port to advertise its transmission rate, duplex mode and flow control (the flow control default is disabled) abilities to its partner. The ports then both operate at the highest common denominator between them.

If connecting a NIC that does not support auto-negotiation or is not set to auto-negotiation, both the device switching port and 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 a device 100BaseT port that is configured to full duplex, the auto-negotiation results in the station attempting to operate in half duplex.

MDI/MDIX

The device supports auto-detection of straight through and crossed cables on all switching 10/100/1000BaseT ports. The feature is part of the Auto-negotiation and is enabled when Auto-negotiation is enabled.

When the MDI/MDIX (Media Dependent Interface with Crossover) is enabled, the automatic correction of errors in cable selection is possible, thus making the distinction between a straight through cable and a crossover cable irrelevant. (The standard wiring for end stations is known as MDI (Media Dependent Interface), and the standard wiring for hubs and switches is known as MDIX.

Flow Control

The device supports 802.3x Flow Control for ports configured with the Full Duplex mode. By default, this feature is disabled. It can be enabled per port. The flow control mechanism allows the receiving side to signal to the transmitting side that transmission must temporarily be halted to prevent buffer overflow.

Back Pressure

The device supports back pressure for ports configured with the half duplex mode. By default, this feature is disabled. It can be enabled per port. The back-pressure mechanism prevents the sender from transmitting additional traffic temporarily. The receiver may occupy a link so it becomes unavailable for additional traffic.

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Configuring PowerConnect 3524/P and 3548/P

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Dell 3548 manual Port Default Settings, Auto-Negotiation, Flow Control, Back Pressure