CHAPTER B | Cables
Twisted-Pair Cable and Pin Assignments
10BASE-T/100BASE-TX
PIN
A
SSIGNMENTS
Use unshielded twisted-pair (UTP) or shielded twisted-pair (STP) cable for RJ-45
connections: 100-ohm Category 3 or better cable for 10 Mbps connections, or
100-ohm Category 5 or better cable for 100 Mbps connections. Also be sure that
the length of any twisted-pair connection does not exceed 100 meters (328 feet).
The RJ-45 ports on the switch base unit support automatic MDI/MDI-X
operation, so you can use straight-through cables for all network connections to
PCs or servers, or to other switches or hubs. In straight-through cable, pins 1, 2,
3, and 6, at one end of the cable, are connected
straight
through
to pins 1, 2, 3,
and 6 at the other end of the cable. When using any RJ-45 port on this switch,
you can use either straight-through or crossover cable.
Table 17: 10/100BASE-TX MDI and MDI-X Port Pinouts
Pin
MDI Signal Name MDI-X Signal Name
1 Transmit Data plus (TD+)
Receive Data plus (RD+)
2 Transmit Data minus (TD-)
Receive Data minus (RD-)
3 Receive Data plus (RD+)
Transmit Data plus (TD+)
6 Receive Data minus (RD-)
Transmit Data minus (TD-)
4,5,7,8
Not used Not used
Note:The “+” and “-” signs represent the polarity of the wires that
make up each wire pair.
STRAIGHT-THROUGH
W
IRING
If the twisted-pair cable is to join two ports and only one of the ports has an
internal crossover (MDI-X), the two pairs of wires must be straight-through.
(When auto-negotiation is enabled for any RJ-45 port on this switch, you can
use either straight-through or crossover cable to connect to any device type.)
You must connect all four wire pairs as shown in the following diagram to
support Gigabit Ethernet.
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