84 APPENDIX A: SPECIFICATIONS AND CABLING REQUIREMENTS
100BASE-TX Operation
100BASE-TX is the IEEE 802.3u standard for Fast Ethernet 
signaling over Category 5 UTP or STP wire at 100 Mbps. 
Based on an extension to the IEEE 802.3 Ethernet 
specification, Fast Ethernet characteristics include:
■ A data rate of 100 Mbps.
■ A broadcast architecture.
■ A specific media-access control (MAC) scheme.
A wiring topology using 100BASE-TX specifies a wiring 
hub, cable arranged in a star configuration, and Category 5 
UTP or STP wiring. Each node has a separate cable run that 
must not exceed 100 meters (328 ft) from the node to 
the hub. 
RJ-45 Connector Pin Assignments
The following illustration shows the RJ-45 connector pin 
assignments for the EtherLink PCI NICs. 
T
X
 D
A
T
A
A
C
T
1
0
1
0
0
L
N
K
12345678
1
2
3
4
5
6
7
8
TD+
TD
_
RD
_
RD+
book  Page 84  Thursday, July 29, 1999  12:23 PM