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RJ45 Connectors (sockets and plugs): The Base-T Standard
uses RJ45 sockets and plugs. The RJ45 socket has 8 pins. The pins
are numbered 1 to 8. Looking at the socket with insertion key facing
down, pin number 1 is to the left.
There are two types of RJ45 plugs: One specifically for CAT6 (has
offset contacts) and another for CAT5E and below.
SOCKETS ("JACKS")
1
8
8
PIN NUMBERS
PLUGS
1
8
1
1
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Appendix B. 10, 100 and 1000 Base-T Basics
Base-T LANs connect LAN devices (PCs, hubs and switches) to
other LAN devices using twisted pair cable. The speed and duplex
of the individual devices (and the proper cable) determine the per-
formance of the LAN. Speed: 10Base-T has a data rate of 10 MB/s
(million bits per second). 100Base-T has a maximum data rate of
100 MB/s. And 1000Base-T has a maximum data rate of 1000 MB/s
(also called "Gigabit"). Duplex: Full duplex allows simultaneous
transmission in both directions. Half duplex is capable of transmitting
in both directions, but only in one direction at a time. Duplex capabil-
ity varies from device to device but most devices are capable of both
half and full duplex.
For two LAN devices to communicate, they both must be operating
at the same speed and duplex. 10Base-T devices always operate
at 10 MB/s. Many 100 and 1000 Base-T devices, on the other hand,
8
can communicate at multiple speeds. Most LAN devices are capable
of "negotiating" down to lower speeds to be compatible with other
devices. As an example, it takes two 100Base-T full duplex devices
to establish a communication link at 100 MB/s, full duplex. See 100
and 1000 Base-T Link Pulses and Data packets on the following
page for additioanl combinations of devices.
HUB/SWITCH
10Base-T
100Base-T
10Base-T
100Base-T
1000Base-T 100Base-T
1000Base-T 1000Base-T 1000 MB/s
Note: Duplex must also match. A full duplex device connected to a
half duplex device will communicate at half duplex.
PC
SPEED
10Base-T
10 MB/s
10Base-T
10 MB/s
100Base-T
10 MB/s
100Base-T
100 MB/s
100 MB/s
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