Allied Telesis AT-9000 Series User Manual
Page 64
Chapter 4: Setting Port Parameters
64
Negotiation— State of Auto Negotiation on a port. Select “Auto” to
enable Auto Negotiation on a port or “Manual” to disable Auto
Negotiation. The default setting is Auto. When the setting for this
field is “Auto,” the Speed and Duplex fields change from white to
brown, and you cannot select them. To change the Speed and
Duplex Mode fields, change the Negotiation setting to “Manual.”
Speed— Port speed. Select 10mb, 100mb, or 1000mb.
Duplex Mode— Sets the duplex modes of the twisted pair ports or
activates Auto-Negotiation manually. The settings are half, full, or
Auto Negotiation. Ports operating in half-duplex mode can either
receive or transmit packets, but not both at the same time. Ports
operating in full-duplex can both send and receive packets,
simultaneously.
Polarity— Sets the wiring configuration of the twisted pair ports
when they are operating at 10 or 100 Mbps, in either half- or full-
duplex mode.
A twisted pair port that is operating at 10 or 100 Mbps can have
one of two wiring configurations. The configurations are known as
MDI and MDI-X. To forward traffic, a port on the switch and a port
on a network device must have different settings. For instance, the
wiring configuration of a switch port has to be MDI if the wiring
configuration on a port on a network device is MDIX.
To set this parameter on a port, you must set the speed and duplex
mode manually. A port that is using Auto-Negotiation sets its wiring
configuration automatically using auto-MDI/MDIX.
Back Pressure Status— Activates or deactivates back pressure
on the ports. Use this field to enable or disable back pressure on
ports that are operating at 10 or 100 Mbps in half-duplex mode.
Back pressure is used by ports during periods of packet
congestion to temporarily stop their network counterparts from
transmitting more packets. This prevents a buffer overrun and the
subsequent loss and retransmission of network packets. A port
initiates back pressure by transmitting on the shared link to cause
a data collision, which causes its link partner to cease
transmission.
Back Pressure Limit (1 - 7935)— Threshold level for back
pressure on a port. Specifies the number of cells for back
pressure. A cell represents 128 bytes. The range is 1 to 7935 cells.
The default value is 7935 cells.
Flow Control Status— Enables or disables the flow control
feature. By default, flow control is disabled on a port.
Flow Control Limit (1 - 7935)— Threshold levels for flow control
on the ports. Specifies the number of cells for flow control. A cell
represents 128 bytes. The range is 1 to 7935 cells. The default
value is 7935 cells.