Allied Telesis X3112 User Manual

Chapter 1: Overview

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The ports are 8-pin RJ-45 connectors that use four pins at 10 or 100 Mbps 
and all eight pins at 1000 Mbps. For the pin assignments, refer to “RJ-45 
Twisted Pair Port Pinouts” on page 78.

A port’s speed can be 10, 100, or 1000 Mbps. The speed can be set 
automatically through Auto-Negotiation, the default setting, or manually 
with the Switchblade x3112 Management Software.

To operate at 1000 Mbps, a twisted-pair port is set to Auto -
Negotiation. You cannot set the speed of a twisted-pair port to 

 

1000 Mbps manually.

A twisted-pair port can operate in either half- or full-duplex mode. (Full-
duplex mode is the only mode available when a port is operating at 1000 
Mbps.) The twisted-pair ports are IEEE 802.3u-compliant and Auto-
Negotiate the duplex mode setting.

You can disable Auto-Negotiation on one or all of the switch ports so that 
you can set the duplex mode manually through the Switchblade x3112 
Management Software.

In order for a switch port to successfully Auto-Negotiate its duplex 
mode with a 10 or 100 Mbps end node, the end node should also be 
configured for Auto-Negotiation. Otherwise, a duplex mode 
mismatch can occur. A switch port using Auto-Negotiation defaults 
to half-duplex if it detects that the end node is not using Auto-
Negotiation. This results in a mismatch if the end node is operating 
at a fixed duplex mode of full-duplex. 

 

 
To avoid this problem when connecting an end node with a fixed 
duplex mode of full-duplex to a switch port, use the Switchblade 
x3112 Management Software to disable Auto-Negotiation on the 
port and set the port speed and duplex mode manually.

The ports have a maximum operating distance of 100 meters (328 feet).