Ethernet is a protocol for carrying information across a network, and it’s the most widely used local area network (LAN) technology in the world. Ethernet outsells all other LAN technologies by a huge margin as evidenced by the hundreds of millions of network interface cards sold over the past 50 years. While Ethernet over Fiber isn’t a new technology, it’s one that extends Ethernet’s capabilities.
A Short History
Ethernet was invented in 1973 to interconnect workstations so they could send data from workstations to printers and to one another. Ethernet was born to a world that used wires; Wi-Fi had yet to be imagined.
However, in 1971, a UFH radio-based communication system launched to connect the Hawaiian islands. Known as AlohaNet, it permitted radio transmitters on each island to broadcast packets of data whenever necessary to pass information to receivers on other islands. This laissez-faire design caused broadcasts to “collide” if two transmitters happened to broadcast at the same time, rendering both broadcasts unintelligible. To solve that problem, designers amended the system so that when collisions were detected, each transmitter would wait a random amount of time before re-broadcasting. Due to such collisions, the AlohaNet achieved only around 18 percent efficiency (later improved to about 37 percent). Nevertheless, AlohaNet served as the foundation of the Ethernet protocol.
Robert Metcalfe had studied AlohaNet for his Ph.D. dissertation, so, in 1973 at the Xerox PARC facility, he included collision detection in his paper that defined the Ethernet protocol. Metcalfe left Xerox in 1979 to found a startup he named 3COM (“Computer Communication Compatibility”), which went on to promote Ethernet and to sell network interface cards for minicomputers, PC workstations, and servers.
Ethernet Becomes a Well-Defined Standard
Ethernet was first defined by the IEEE in 1985 as IEEE 802.3 Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications. Initially, Ethernet used thick coaxial cable to interconnect devices. A later enhancement (10BASE2) moved Ethernet protocol to thin coax, and that was followed by amendments that allowed 10BASE-T Ethernet to function over now-ubiquitous unshielded twisted-pair (UTP) wiring and, even later, over fiber optic cables. These were all developed as supplements to the IEEE Ethernet standard.
Among the many technical details surrounding Ethernet technology that evolved over the years, one stands out. Early Ethernet used the coax cable as a bus. Every device on the network would listen for data coming across the cable but would ignore all data packets except those intended for each device. This meant the bandwidth available on the bus was limited depending on how many devices were transmitting. And, when simultaneous transmissions occurred, the random time delays required by the collision detection protocol further reduced the available bandwidth.
Today though, rather than using the cable as a bus, modern Ethernet LANs configure each workstation on the network, so it communicates directly with a switch, which eliminates the need for collision detection and the consequent bandwidth limitations.
Why Use Fiber?
The short answer: Data travels at dramatically higher speeds and over longer distances using fiber.
No matter the type of copper wiring used, every cable has a theoretical distance limit beyond which data integrity is compromised. Modern Ethernet can use several kinds of copper wiring including Cat5, Cat5e, Cat6, and Cat6a — all of which can carry signals reliably up to 100 meters (328 feet). Cat7 cable can handle speeds up to 100 Gbps, however only for 15 meters (just under 50 feet).
Fiber optic cable, however, can reliably carry data over far greater distances. Fiber optic cables come in two basic designs. Single-mode fiber cables can only pass one ray of light through its tiny fiber core, which is typically less than 10 µm in diameter. That microscopic diameter increases the cost of transceivers that inject and receive light at either end of the cable run. It also makes terminating single-mode fiber in the field difficult or sometimes impossible, which is why some single-mode cables makers terminate single-mode products at the factory.
Multimode fiber has a larger fiber core that measures either 50 µm or 62.5 µm. With its larger core, the cost of transceivers needed to inject and receive light signals can cost up to 75 percent less than single-mode transceivers. Further, multimode cables can carry several light injections of varying frequencies.
As for distances, fiber cable designs offer the following.
| Nomenclature | Fast Ethernet 100 Mbps | 1 Gbps | 10 Gbps | 40 Gbps | 100 Gbps | 40G SWDM4 | 100G SWDM4 | |
| Multimode | OM1* | 2 km | 275 m | 33 m | — | — | — | — |
| OM2 | 2 km | 550 m | 82 m | — | — | — | — | |
| OM3 | 2 km | 800 m | 300 m | 100 m | 100 m | 240 m | 75 m | |
| OM4 | 2 km | 1100 m | 400 m | 150 m | 150 m | 350 m | 100 m | |
| OM5 | 2 km | 1100 m | 400 m | 150 m | 150 m | 440 m | 150 m | |
| Single Mode | OS1 & OS2 | 40 km | 100 km | 40 km | 40 km | 40 km | — | — |
* OM1 is considered obsolete except for restoring legacy networks that require OM1.
Conclusion
Multimode fiber covers enough distance at various speeds to satisfy the needs of most data centers. Plus, it’s less expensive than single-mode cabling as is the hardware needed to support it.
Extended Office Solutions has years of experience designing networks with Ethernet over copper as well as over fiber. We can help you develop a super high-speed and scalable broadband network delivered over a private line. You’ll have future-proofed, reliable, high speed performance that’s required to remain competitive in today’s ever-changing marketplace.
Contact us to discuss your requirements or to learn how Ethernet over Fiber can deliver the performance you need today and in the future.
