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Let’s delve into the world of 1000Base-SX, a critical standard in the Ethernet realm.

What is 1000Base-SX?

1000Base-SX is a type of standard for implementing Gigabit Ethernet networks. The SX in 1000BaseSX stands for short, and it indicates that this version of Gigabit Ethernet is intended for use with short-wavelength transmissions over short cable runs of fiber-optic cabling. The “X” refers to the physical medium of the fiber optic cabling. Gigabit Ethernet standards are defined in the 802.3z standards of Project 802 developed by the IEEE.

1000BaseSX technologies are in the beginning stages of being widely implemented in enterprise-level networks and are primarily used for shorter cable runs between pieces of equipment within a building.

How It Works

1000BaseSX is an extension of standard Ethernet technologies to gigabit-level network speeds.

Utilizing short wavelength signals typically around 850 nanometers, 1000Base-SX operates over multi-mode fiber using a pair of fiber optic strands, one for transmitting and one for receiving data. A significant advantage of this standard is its ability to transmit data at Gigabit speeds over relatively short distances, generally up to 550 meters, making it suitable for local network applications.

1000BaseSX is implemented using only multimode fiber-optic cabling. Cable segment lengths depend on the cable grade used, as shown in the following table.

Cable GradeMaximum Segment Length
50-micron multimode fiber500 meters
62.5-micron multimode fiber220 meters
1000Base-SX Cable Segment Lengths

1000Base-SX is intended mainly for connecting high-speed hubs, Ethernet switches, and routers together in different wiring closets or buildings using long cabling runs. 1000BaseSX is most commonly implemented in a switch-switch configuration.


When multimode fiber-optic cabling is used in 1000BaseSX implementations, a condition called differential mode delay (DMD) can sometimes occur. This condition occurs only in cabling of uneven quality, and it leads to signal jitter that can disrupt network communications. To resolve this problem, newer 1000BaseSX transceivers condition the signal to distribute its power equally among all transmission modes of the cable.

Related products

10Gtek for Cisco GLC-SX-MMD/ GLC-SX-MM/ SFP-GE-S, Gigabit SFP SX Transceiver, 1000Base-SX, MMF, 850nm, 550m

1000Base-SX Module

See also:

Further reading:

1000BASE-SX is a fiber optic Gigabit Ethernet standard for operation over multi-mode fiber using a 770 to 860 nanometer, near-infrared (NIR) light wavelength. The standard specifies a distance capability between 220 meters and 550 meters. In practice, with good-quality fiber, optics, and terminations, 1000BASE-SX will usually work over significantly longer distances.

This standard is highly popular for intra-building links in large office buildings, co-location facilities and carrier-neutral Internet exchanges. 1000BASE-SX SFP works at 850nm wavelength and used only for the purposed of the multimode optical fiber with an LC connector. 1000BASE-SX SFP traditional 50 microns of multimode optical fiber link is 550 meters high and 62.5-micron fiber distributed data interface (FDDI) multimode optical fiber is up to 220 meters.