3Com 3CR990, User Manual

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Network Cable 67
The 10BASE-T name indicates a signaling speed of 10 Mbps and twisted-pair
wiring.
Base stands for baseband, which denotes a technique for transmitting
signals as direct-current pulses rather than modulating them onto separate
carrier frequencies.
A wiring topology using 10BASE-T specifies a wiring hub, cable arranged in a star
configuration, and unshielded twisted-pair cable. Each node has a separate cable
run that must not exceed 328 ft. (100 meters) from the node to the hub.
100BASE-TX Description 100BASE-TX is the IEEE 802.3u standard for Fast Ethernet signaling over
Category 5 UTP or STP wire at 100Mbps.
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 328 ft. (100 meters) from the node to the hub.
RJ-45 Connector Pin
Assignments
The following figure shows the pin layout for the RJ-45 connector socket on the
NIC backplate.
TX D
ATA
ACT
10
100
L
N
K
1 2 3 4 5 6 7 8
1
2
3
4
5
6
7
8 TD+
TD_
RD_
RD+