C
ONNECTIVITY
R
ULES
2-7100 Mbps Fast Ethernet Collision Domain

Maximum Fast Ethernet Cable Distance

SMC 3-2 Rule for Class II Repeaters

SMC 2-1 Rule for Class I Repeaters

Type Cable Type Max. Cable Length
100BASE-TX Category 5 100-ohm UTP or STP 100 m (328 ft.)
100BASE-FX
Multimode
50/125 or 62.5/125 micron core
multimode fiber (MMF)
2 km (1.24 miles)
100BASE-FX
Single-Mode
9/125 micron core single-mode fiber
(SMF)
20 km (12.43 miles)
Between any two PCs or other stations in the same 100BASE-TX collision
domain, there may be:
• up to 3 link segments
• up to 2 Class II repeaters (hubs)
Between any two PCs or other stations in the same 100BASE-TX collision
domain, there may be:
• up to 2 link segments and
•up to 1 Class I repeater (hub)