Everything You Need to Know About Fiber Optic Ethernet

In the last decade, a wide variety of applications have been developed that covers a dozen of datacom networking technologies. The transmission speed ranges from 10Mbits up to 10Gbit/s and growing.

High distance-bandwidth product is the major selling point for fiber optic transceivers. Another major benefit of fiber optic systems is their high reliability compared to other media.

Now fiber optic transceivers are commercially available for almost all international and industrial standards, including Ethernet, Fast Ethernet, Gigabit Ethernet, 10Gbit Ethernet.

So let's review the the bunch of industry standards and inspect the various applications that fiber optic transceivers provide.

There are two classifications for optical fiber: single-mode (SMF) and multi-mode (MMF). SMF is used for long distance communication and MMF is used for distances of less than 300 m. SMF has a narrower core (6.3 µm) which makes it difficult to connect. MMF has a wider core (50 or 62.5 µm) and is more expensive than SMF.

Ethernet

Ethernet is the result of research done at Xerox Corporation in the early 1970s. It has evolved into the most popular physical and link layer protocol today. Up until late 1980s, 10Mbit/s Ethernet had the largest installed base and was the most popular networking standard.

Fast Ethernet

By the mide of 1990s, all 10Mbit/s Ethernet installation base have been upgraded to 100Mbit/s Fast Ethernet. The fiber standards for Fast Ethernet includes 100Base-FX, 100Base-SX and 100Base-BX.

100Base-FX uses a 1300nm multimode light. The maximum length is 2 kilometers for full duplex over multimode optical fiber.

100Base-SX is the lower cost alternative to 100Base-FX. It uses 850nm light and can only operate at distance up to 300 meters.

100Base-BX is version of Fast Ethernet over a single strand of optical fiber. (Both 100Base-FX and 100Bse-SX use two strands of optical fibers). It uses WDM (wavelength division multiplexing) technology to separate the transmission and receiving signals.

Gigabit Ethernet

By the end of 1990s and early 2000s, most 100Mbit/s Fast Ethernet installation base have been upgraded to 1000Mbit/s Gigabit Ethernet. In the same process, fiber is increasingly the transmission medium of choice when copper reaches its fundamental limits for high speed transmission.

For fiber optic transceivers, the related industry standards include 1000Base-SX, 1000Base-LX, 1000Base-LH, 1000Base-BX10 and 1000Base-ZX.

1000Base-SX uses 850nm multimode light over multimode fibers. Its spec says the maximum operation length is 500 meters but usually it can reach much longer than that.

1000Base-LX uses 1300 or 1310nm single mode fiber and laser. Its specification says the maximum operation length is 5km. But manufacturers often guarantee over 10km working length.

1000Base-LH is not a standard but accepted by the industry. It is backward compatible with 1000Base-LX but its specification is 10km over single mode fiber. This is actually achieved by using high quality fiber optic components.

1000Base-BX10 operates over a single strand of single mode fiber. Similar to 100Base-BX, this is achieved by using WDM technology. Its specification is 10km.

1000Base-ZX is also not a industry standard by accepted by the industry. It uses 1550nm single mode fiber and laser to operate over 70km.

10Gbit Ethernet

10Gbit Ethernet is also called 10GigE. This was first published in 2002 and is still the fastest Ethernet standard, although 100Gbit Ethernet is under development. The standard includes 10GBase-SR, 10GBase-LR, 10GBase-LRM, 10GBase-ER, 10GBase-ZR and 10GBase-LX.