122
Pin
10BASE-T/100BASE-TX 1000BASE-T
Signal Function Signal
Function
4
Reserved
—
BIDD+
Bi-directional data cable D+
5
Reserved
—
BIDD-
Bi-directional data cable D-
6
Tx-
Send data
BIDA-
Bi-directional data cable A-
7
Reserved
—
BIDC+
Bi-directional data cable C+
8
Reserved
—
BIDC-
Bi-directional data cable C-
To ensure normal communication, the pins for sending data on one port should correspond to the
pins for receiving data on the peer port. When both of the ports on the two devices are MDI or MDIX,
a crossover Ethernet cable is needed. A cross-over cable connects devices of the same type. When
one port is MDI and the other is MDIX, a straight-through Ethernet cable is needed. A
straight-through cable connects devices of different types.
If an RJ-45 Ethernet port with MDI/MDIX autosensing enabled can automatically negotiate pin roles.
The 7500 RJ-45 Ethernet ports support MDI/MDIX. By default, MDI/MDIX is enabled on a port.
Making an Ethernet twisted pair cable
1.
Cut the cable to length with the crimping pliers.
2.
Strip off an appropriate length of the cable sheath. The length is typically that of the RJ-45
connector.
3.
Untwist the pairs so that they can lie flat, and arrange the colored wires based on the wiring
specifications.
4.
Cut the top of the wires even with one another. Insert the wires into the RJ-45 end and make
sure the wires extend to the front of the RJ-45 end and make good contact with the metal
contacts in the RJ-45 end and in the correct order.
5.
Crimp the RJ-45 connector with the crimping pliers until you hear a click.
6.
Repeat the above steps with the other end of the cable.
7.
Use a cable tester to verify the connectivity of the cable.
Optical fiber
CAUTION:
Use the same types of transceiver modules, pigtail cords, patch cords, and fiber cables. If you use
single-mode optical fibers, the transceiver modules, pigtail cords, patch cords, and fiber cables must
be single-mode.
Optical fiber
Optical fibers are widely used in fiber-optic communications, which are advantageous for
long-distance communications.
Optical fibers can be classified into the following types:
•
Single mode fiber
—It has a core size of 10 µm, and has a lower modal dispersion. It carries
only a single ray of light. It is mostly used for communication over longer distances.
