Connectivity Rules
4-5
4
A 1000BASE-LX or 1000BASE-SX SFP fiber optic ports operate at 1000 Mbps full
duplex, with auto-negotiation of flow control. The maximum length for fiber optic
cable operating at Gigabit speed will depend on the fiber type as listed under
“1000 Mbps Gigabit Ethernet Collision Domain” on page 4-5.
Connectivity Rules
When adding hubs (repeaters) to your network, please follow the connectivity rules
listed in the manuals for these products. However, note that because switches break
up the path for connected devices into separate collision domains, you should not
include the switch or connected cabling in your calculations for cascade length
involving other devices.
1000BASE-T Cable Requirements
All Category 5 UTP cables that are used for 100BASE-TX connections should also
work for 1000BASE-T, providing that all four wire pairs are connected. However, it is
recommended that for all critical connections, or any new cable installations,
Category 5e (enhanced Category 5) or Category 6 cable should be used. The
Category 5e and 6 specifications include test parameters that are only
recommendations for Category 5. Therefore, the first step in preparing existing
Category 5 cabling for running 1000BASE-T is a simple test of the cable installation
to be sure that it complies with the IEEE 802.3ab standards.
1000 Mbps Gigabit Ethernet Collision Domain
Table 4-1. Maximum 1000BASE-T Gigabit Ethernet Cable Length
Cable Type Maximum Cable Length Connector
Category 5, 5e, or 6 100-ohm UTP or STP 100 m (328 ft) RJ-45
Table 4-2. Maximum 1000BASE-SX Gigabit Ethernet Cable Lengths
Fiber Size Fiber Bandwidth Maximum Cable Length Connector
62.5/125 micron
multimode fiber
160 MHz/km 2-220 m (7-722 ft) LC
200 MHz/km 2-275 m (7-902 ft) LC
50/125 micron multimode
fiber
400 MHz/km 2-500 m (7-1641 ft) LC
500 MHz/km 2-550 m (7-1805 ft) LC
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