Mdi/Mdix; Flow Control; Back Pressure; Switching Port Default Settings - Dell PowerConnect 54 Series User Manual

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, 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 to half duplex mode. By default, this feature is
disabled. It can be enabled per port. The back pressure mechanism prevents the transmitting side from
transmitting additional traffic temporarily. The receiving side may occupy a link so it becomes unavailable
for additional traffic.

Switching Port Default Settings

The following table gives the port default settings.
Table 3-3. Port Default Settings
Function
Port speed and mode
Port forwarding state
Port tagging
Flow Control
Back Pressure
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Installing the PowerConnect Device
Default Setting
10/100/1000BaseT copper: auto-negotiation full duplex
Enabled
No tagging
Off (disabled on ingress)
Off (disabled on ingress)