Military Embedded Systems

The 31 flavors of Ethernet


January 06, 2015

Ronen Isaac


ETHERNET EVERYWHERE BLOG: Our last blog covered the basic subject of why Ethernet is a good choice for military and embedded applications. Now that Why has been explained, I thought that I would spend some time talking about the What? Most people are often surprised by the different flavors, so to speak, of Ethernet that exist. I’m not sure that there are actually 31 flavors, but for this discussion, it is close enough.

Driven by the concept of the Internet of Things, Ethernet has seen explosive innovation to enable the connection of everything to everything. So it’s good to take a look back and then we’ll take a look forward at some of these new innovations.

To read Isaac's blog on "Why Ethernet?" click here.

Ethernet was introduced in the 1970s, the first Ethernet ratified as a standard in the 1980. It is measured in millions of bits per second (Mbps). The first iteration, now known as Standard Ethernet, ran at a rate of 10 Mbps.

In 1995 Fast Ethernet was introduced. Fast Ethernet is a collective term for a number of Ethernet standards that carry traffic at the nominal rate of 100 Mbit/s. Of the Fast Ethernet standards, 100BASE-TX is by far the most common and runs over two copper wire-pairs inside a category 5 or above cable. Fast Ethernet also runs over several variants of optical fiber including 100Base-FX, 100Base-BX and 100BaseLX. Each of these versions of optical fibers has a trade-off between cost, wavelength type, and distance that the wavelength can travel. Today, Fast Ethernet is used for device connectivity within a local area network.

Today, Gigabit Ethernet, or GigE, is one of the most pervasive Ethernet standards and speeds. It carries traffic at 1000 megabits, or 1 gigabit per second. It’s most common application is a local area network (LAN) connection between devices on that same network using either optical fiber (1000BASE-X), or twisted pair cable (1000BASE-T).

Due to its low latency and high throughput, 10 Gigabit Ethernet has become the defacto standard for connecting routers, switches, servers, and storage within a data center or enterprise backbone. 10 Gigabit Ethernet uses only full duplex point-to-point links over higher-grade copper and fiber cables.

To keep up with the exponential demand for and sharing of data, Ethernet has taken some huge leaps in speed over the last five years. In 2010 the IEEE took an unprecedented step and ratified two Ethernet standards at once -- the 40 GbE standard for local server applications and the 100 GbE rate for Internet backbones. Together these standards are known as Higher Speed Ethernet. 40 GbE consolidates four lanes of 10GbE and 100 GbE consolidates four lanes of 25GbE (a totally new technology). 40 GbE is gaining fast momentum in connecting servers and routers to each other within a data center (east/west traffic) while service providers are implementing 100 GbE in there network backbones (north/south traffic). Both standards require higher-speed optical fibers to make the connections.

Earlier this year, the IEEE started forming working group task forces to create standards for implement both 25GbE (a single lane of the four 25 GbE lanes developed to support 100 GbE) and 400 GbE (the consolidation of four 100 GbE links).

As Ethernet becomes more and more pervasive as the technology of choice to connect devices and data transmission from our person, to our desktop to our home, to our cars over wired and wireless networks, it will continue to evolve. The beauty of Ethernet is that, as a standard, no matter what speed a device supports, all speeds are backwards compatible through switches and routers and devices that use Ethernet as a standard connection will always be able to communicate with each other.


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