1000BASE-T (also known as IEEE 802.3ab) is a standard for Gigabit Ethernet over copper wiring (RJ45 connection). It requires, at least Category 5 cable (the same as 100BASE-TX), but Category 5e (Category 5 enhanced) or Category 6 cable may also be used and are often recommended. 1000BASE-T requires all four pairs to be present and is far less tolerant of poorly installed wiring than 100BASE-TX.
|1||BI_DA+||Bi-directional pair A +|
|2||BI_DA-||Bi-directional pair A -|
|3||BI_DB+||Bi-directional pair B +|
|4||BI_DC+||Bi-directional pair C +|
|5||BI_DC-||Bi-directional pair C -|
|6||BI_DB-||Bi-directional pair B -|
|7||BI_DD+||Bi-directional pair D +|
|8||BI_DD-||Bi-directional pair D -|
Each network segment cable length may be up to 100 meters, although several chip manufacturers claim 150 meters. Autonegotiation is a requirement for using 1000BASE-T, according to the standard. Several device drivers will allow you to force 1000 Mbps full duplex to eliminate autonegotiation issues. If pins 4,5,7 & 8 are not connected or punched properly the speed falls back to 100 mbps.