Ethernet Over Fiber-Optics: As clear as glass!

As the demand for Ethernet connectivity increases in the market, so do the demands on Ethernet connectivity.  By transmitting Ethernet signals over fiber-optic cabling, users are able to extend the distance Ethernet signals will reach, protect against external Electro-Magnetic Interference (eliminating internal), and shield products from electrical surges.  All in all – by transmitting your data through light in a glass cable, fiber-optic connectivity is a great way to get more out of your Ethernet connections!

While the sales pitch on fiber above certainly sounds appealing, there are many aspects to consider during a migration to fiber-optic connectivity.  In order to select the best fiber optic connectivity solution, we must address:

1. Type of fiber-optic communication
2. Bandwidth
3. Fiber-optic connection type

Relating directly to these concerns, users must ask themselves

1. Type of fiber-optic communication

How do I want my data to be sent over fiber?

fiber-optic communication Fiber-optic communication is available in two different forms: Single-Mode and Multi-Mode.  Single-Mode, generally associated with longer distance capabilities, provides a hyper-efficient mode of transportation for the data-carrying light signals.  Multi-Mode fiber, while less expensive, is a less efficient method of fiber transmission.  As data travels across Single-Mode fiber it will degrade less than it would over the same distance with Multi-Mode fiber.

Furthermore, each fiber strand is designed to support a specific wavelength of fiber transmission.  Wavelength, measuring the distance between successive crests of a light wave, also influences efficiency and distance fiber can be transmitted.

Typically, Multi-Mode fiber is used when the distance data must travel is 2km or less.  Single-Mode fiber has the capability to transmit data up to 100+km.

Paring this all down there are two key things to note:

  • Both sides of a fiber connection must communicate on the same type of fiber: Single-Mode or Multi-Mode
  • Both sides of a fiber connection must communicate over the same wavelength

2. Bandwidth

How much data will I be sending? (“size of the pipe”)

Much like sending Ethernet signals over copper cabling, the amount of data you need to transmit is a key piece to identify.  When speaking of copper Ethernet, a 10/100/1000 (Gigabit) connection means that any connection initiated in either 10 megabits per second (Mbit/s), or up to 100 Mbit/s will be supported.

The same basic logic applies with fiber-optics.  However, when working with fiber-optics the bandwidth is not “backwards” compatible.  For example, a 1000BASE (Gigabit) fiber connection will NOT support a 100BASE fiber connection.

ethernet fiber-optic bandwidth communication

While you can run less than 1000 Mbit/s through a 1000BASE fiber connection, the connection must be initiated in 1000BASE (Gigabit) communication on both sides.

This brings us to a third key point of fiber-optic Ethernet communication:

3. Fiber-optic connection type

How will I connect the fiber on both sides of the cable?

With the big questions answered we can now move further out towards the connections on each end.  This is the area in which Comtrol specializes, connecting end devices to fiber-optic data transmission.

Typically, copper Ethernet is handled through the very familiar RJ45 cable end. Fiber-optics is not so cut and dry – there are MANY options for connection:

fiber optic connection Ethernet communication

SC, ST, and LC – Three types of fiber connections that all bring fiber signals into a device in a similar way but do so through a different connector.  Similar to a serial port with DB9 vs. RJ45 connection, certain advantages exist for each type on both the cabling and device side, however at the end it comes back to main decision factors of:

  • Existing System Design
  • Personal Preference

Second, moving beyond the physical connector type we must consider fixed optics or SFP modules.

Built-in fiber ports, commonly known as fixed optics, are just that – built in to the fiber device and unable to change.  Comtrol’s ES8108F, for example, has fixed optics.  After selecting the ES8108F, you have the option to select Single-Mode or Multi-Mode fiber, which look identical but have different fiber capabilities.

fixed optic fiber ports ethernet fiber communication

Modular fiber ports, commonly achieved through the use of Small Form-factor Pluggable (SFP) modules, allow the fiber connection on a device to be decided based on the SFP model used not the model of the base switch used.  SFP modules allow you to select the type of fiber communication, bandwidth of connection, and connector type outside of the switch.


Ethernet switches, such as the Comtrol RocketLinx® ES85XX series, require an additional piece of hardware, the SFP, to enable fiber connections.  This additional piece of hardware, however, allows much greater flexibility.  No longer is the type of fiber connection limited to your switch selection but rather it can be switched around dependent on your specific system needs as they change!

All things considered, fiber is a powerful media to connect Ethernet devices together.  By utilizing fiber in a long distance connection, high interference area, or critical area of communication you can be sure of one thing: The data you send will be clear as glass on the other end!

Contact your Comtrol sales representative to learn about our growing fiber-optic connectivity options and learn how it may benefit your system today and long into the future!

For more information, contact Joe House 763.957.6127

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