10BASE-T is an implementation of Ethernet which allows stations to be attached via twisted pair cable. The name 10BASE-T is derived from several aspects of the physical medium. The 10 refers to the transmission speed of 10 Mbit/s. The BASE is short for baseband. This means only one Ethernet signal is present on the send and/or receive pair. In other words there is no multiplexing as with broadband transmissions. The T comes from twisted pair, which is the type of cable that is used.
10BASE-T uses RJ-45 jacks wired to either the TIA-568A or TIA-568B standard. Only the second and third pairs are used (orange and green). If the wiring standard is identical on both ends the segment is a patch cable suitable for transmission between a hub/switch/patch panel and a node. If the wiring standards are opposite on either end the segment is a crossover cable suitable for connecting a node to a node or a hub/switch to another hub/switch. The EIA/TIA 586 standards are as follows:
25 Pair Color Code Chart
RJ-45 Wiring (EIA/TIA-568A)
Pin
Pair
Wire
Color
1
3
1
white/green
2
3
2
green/white
3
2
1
white/orange
4
1
2
blue/white
5
1
1
white/blue
6
2
2
orange/white
7
4
1
white/brown
8
4
2
brown/white
RJ-45 Wiring (EIA/TIA-568B)
Pin
Pair
Wire
Color
1
2
1
white/orange
2
2
2
orange/white
3
3
1
white/green
4
1
2
blue/white
5
1
1
white/blue
6
3
2
green/white
7
4
1
white/brown
8
4
2
brown/white
10BASE-T was the first vendor-independent standard implementation of Ethernet on twisted pair wiring. However, it was in fact an evolutionary development from AT&T StarLAN which had both 1 Mbit/s and 10 Mbit/s versions. 10BASE-T is essentially StarLAN-10 with the addition of the link-beat.
In the OSI model, 10BASE-T is at the physical layer. Ethernet encompasses both addressing at the data link layer and a number of physical-layer implementations. In this model, 10BASE-T is one of the possible physical layer standards for ethernet-- some others include 10BASE2, 10BASE5, and 100BASE-TX. Network layer protocols, such as IP, do not generally need to know whether they are being hosted on 10BASE-T or not, provided they know that they are being hosted on Ethernet.
