Ethernet segment distances UTP: Gigabit Ethernet, 1000BASE-T, 802.3ab, 1999 Length: 100m Cable: UTP (Cat5) - 4 pairs Fast Ethernet, 100BASE-TX, 802.3u, 1995 Length: 100m Cable: UTP (Cat5) - 2 pairs Fast Ethernet, 100BASE-T4, 802.3u, 1995 Length: 100m Cable: UTP (Cat3) - 4 pairs Fast Ethernet, 100BASE-T2, 802.3y, 1998 Length: 100m Cable: UTP (Cat3) - 2 pairs Twisted Pair Ethernet, 10BASE-T, 802.3i, 1990 Length: 100m Cable: UTP (Cat3) - 2 pairs 1000BASE-CX Length: 25m (requires new type of shielded cable) FIBER OPTIC: 10BASE-FL (Multimode fibre), 802.3j, 1993 Length: 2km 100BASE-FX (Multimode fibre), 802.3u, 1995 Length: 412m (Half-duplex), 2km (Full-duplex) 100BASE-FX (Singlemode fibre) Full-Duplex ONLY, 802.3u, 1995 Length: 2 - 40km *(see note) 1000BASE-X, 802.3z, 1998 1000BASE-LX Length: 550m (62.5um or 50um multimode fibre) 3km (10um singlemode fibre) 1000BASE-SX Length: 250m (62.5um multimode fibre) 550m (50um multimode fibre) COAXIAL: Thin Ethernet, 10BASE-2, 802.3a, 1985 Length: 185m Cable: RG-58 Thick Ethernet, 10BASE-5, 802.3, 1983 Length: 500m Cable: RG-58 *NOTE: These lengths can vary by equipment vendor. Some products enable 100Mbps Full Duplex over 100km now.