Port Settings - TRENDnet TI-PG1284i User Manual

TRENDnet User's Guide

Port Settings


Duplex mode
A duplex communication system is a system composed of two connected parties or
devices that can communicate with one another in both directions.
Half Duplex:
A half-duplex system provides for communication in both directions, but only one
direction at a time (not simultaneously). Typically, once a party begins receiving a signal,
it must wait for the transmitter to stop transmitting, before replying.
Full Duplex:
A full-duplex, or sometimes double-duplex system, allows communication in both
directions, and, unlike half-duplex, allows this to happen simultaneously. Land-line
telephone networks are full-duplex, since they allow both callers to speak and be heard
at the same time.

Loopback Test
A loopback test is a test in which a signal in sent from a communications device and
returned (looped back) to it as a way to determine whether the device is working right or
as a way to pin down a failing node in a network. One type of loopback test is performed
using a special plug, called a wrap plug that is inserted in a port on a communications
device. The effect of a wrap plug is to cause transmitted (output) data to be returned as
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received (input) data, simulating a complete communications circuit using a single
computer.

Auto MDI-MDIX
Auto-MDIX (automatic medium-dependent interface crossover) is a computer
networking technology that automatically detects the required cable connection type
(straight-through or crossover) and configures the connection appropriately, thereby
removing the need for crossover cables to interconnect switches or connecting PCs peer-
to-peer. When it is enabled, either type of cable can be used or the interface
automatically corrects any incorrect cabling. For Auto-MDIX to operate correctly, the
speed on the interface and duplex setting must be set to "auto". Auto-MDIX was
developed by HP engineers Dan Dove and Bruce Melvin.

Auto Negotiation
Auto (auto-negotiation) allows one port to negotiate with a peer port automatically to
obtain the connection speed and duplex mode that both ends support. When auto-
negotiation is turned on, a port on the Switch negotiates with the peer automatically to
determine the connection speed and duplex mode.
If the peer port does not support auto-negotiation or turns off this feature, the Switch
determines the connection speed by detecting the signal on the cable and using half
duplex mode. When the Switch's auto-negotiation is turned off, a port uses the pre-
configured speed and duplex mode when making a connection, thus requiring you to
make sure that the settings of the peer port are the same in order to connect.

Flow Control
A concentration of traffic on a port decreases port bandwidth and overflows buffer
memory causing packet discards and frame losses.IEEE802.3x flow control is used in full
duplex mode to send a pause signal to the sending port, causing it to temporarily stop
sending signals when the receiving port memory buffers fill and resend later.
The Switch uses IEEE802.3x flow control in full duplex mode and backpressure flow
control in half duplex mode. IEEE802.3x flow control is used in full duplex mode to send
a pause signal to the sending port, causing it to temporarily stop sending signals when the
receiving port memory buffers fill. Back Pressure flow control is typically used in half
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