What is optical networking?

How does optical networking work?

At the simplest level, optical networking works by encoding data into light pulses, then sends those pulses some distance to a receiver, which then decodes the pulses back into digital data.

Technically, optical networking doesn’t require a transmission substrate; two next-door friends sending each other Morse code messages by switching a flashlight on and off would qualify for the strictest definition of optical networking.

Though in common conversation, optical networking is about the practice of encoding computer data into light pulses, then transmitting them across glass or plastic fiber optic cables to a receiver.

The key part of that definition is “light” pulses: the definition of optical networking requires that the information is encoded into light waves.

These light pulses carry data using optical signal modulation. A different wavelength or amplitude of the light wave is converted by the receiver into electronic data at the point of reception.

Because an optical wave’s wavelength and amplitude allow for transmitting more information in each pulse than a traditional electrical signal, optical networks can provide higher bandwidth than traditional electrical networking.

Additionally, fiber optic cables carry lower network latency over long distances, due to their ability to send information much further without requiring network repeaters. Copper cables can only carry information a few hundred feet before needing the signal to be re-boosted.

Fiber optic cables can carry a signal for miles before needing to repeat the transmission. Each repeat carries a latency cost as the data needs to be decoded and then re-encoded into electrical pulses.

What are the key components of optical networking?

When you’re looking at a fiber optic network, the first key decision to make involves what type of fiber optic cable you’ll run. The two types of fiber optic cable are single-mode and multi-mode.

The technological difference is that single-mode fiber uses a much narrower optical cable, which is only able to transmit a single, direct pulse of light at a time. Multi-mode cable is wider, which allows the light to bounce off the sides of the cable at multiple angles (referred to as modes).

1. Single-mode fiber

Single-mode fiber optic cables handle much longer distances (up to 100km or more) effectively, and they can handle very large amounts of data quickly. However, the equipment required for handling single-mode fiber is much more expensive than multi-mode fiber.

2. Multi-mode fiber

Multi-mode fiber is better suited for shorter distances like those needed for Local Area Networks (LANs).

Regardless of the mode of fiber optic cable that you use, there are other pieces of hardware that you’ll need to run a network effectively.

3. Transponder

The first piece of equipment is a transponder. This is the piece of equipment that converts short-range light pulses into electrical signals, and then into long-range optical pulses through a process known as Optical-Electrical-Optical (OEO).

A transponder is a must any time you wish to take short-range optical networking signals and move them onto long-haul fiber optic cables.

4. Optical line terminal

The second non-negotiable is an optical line terminal. This piece of equipment serves as the central hub of optical signals within a network. It handles traffic management across the entire network.

How do I manage capacity on an optical network?

Optical networks improve both bandwidth and latency of data transmission. These features make them highly desirable for short- and long-range data transmission. Unfortunately, wiring every network endpoint to its own fiber optic cable is an unreasonable goal, due to space and cost constraints.

That means that optical network managers need to manage capacity within their networks. Fortunately, optical network technicians have provided different technologies for capacity management.

The most powerful tool in the capacity-planning toolbox is wavelength division multiplexing (WDM).

WDM allows for sending multiple channels of data across a single fiber optic cable by changing the wavelength of the transmitted light. WDM comes in two flavors: coarse (CWDM) and dense (DWDM).

CWDM uses light ranges where the wavelengths have a substantial difference between peaks, while DWDM uses light ranges where the wavelengths are packed much more tightly together. The result is that DWDM has much higher network capacity in terms of:

• Endpoints supported
• Data bandwidth
• Distance transmitted

Historically, CWDM has been a cheaper technology to implement. However, that math has changed in recent years, once future capacity planning is included in the rollout costs.

DWDM is capable of supporting as many as 4X the channels as CWDM, meaning that in any environment where long-haul data transmission or future capacity scaling is a concern, DWDM is often the right choice both for performance and long-term cost of ownership.

How does optical networking compare to traditional copper networks?

It’s natural to compare optical networking with traditional copper or Ethernet networks. These networks are familiar to many people due to existing connectivity via telephone or cable connections to their homes.

While there are an expanding number of fiber optic rollouts in communities across the world, it’s important to understand the differences between these technologies and why one might choose one over the other.

What are the benefits of optical networks?

When companies are considering adopting optical networking for their use case, they’re usually targeting a handful of major benefits:

1. High capacity

Optical networks have very high bandwidth and very low latency, allowing a large amount of data to be transmitted quickly

2. Long reach

Optical networks support very long data transmission distances, often up to 100 or more kilometers.

3. Energy efficiency

The energy needed to transmit data via light is much lower than that required to transmit electricity across a copper wire, decreasing operational costs.

When companies are thinking about engaging in a fiber rollout, they’re usually targeting one of a few different use cases.

4. Connecting datacenters

If your company has multiple physical datacenters located in different regions, optical networks are a great way to create high-bandwidth, low-latency connections between the points.

5. Internet metro backbone

Every metro area needs to connect to the internet at some point to create connections to other metro areas. Optical networks handle the very high traffic loads required for thousands of customers.

6. Enterprise-wide area networks (WAN)

Enterprise clients often desire to connect physically disparate offices to one another with high-speed network connections in a WAN. The ability to send data between offices in different locales as if they were on the local area network (LAN) is critical in today’s high-data environments.

7. 5G backhaul

While 5G networking is wireless and transmits over radio signals, it is still simpler and cheaper to do long-distance data transmission over physical cables. Fiber optic cables are the perfect medium for supporting this use case.

What kinds of deployment challenges do optical networks face?

Just like any other technology, optical networks come with their own drawbacks. While there are many positives to adopting optical networks, there are a few main drawbacks to adopting fiber optics.

1. Fiber optic cables cannot be crimped or twisted

Unlike traditional copper networks, fiber optic cables cannot be crimped or twisted. This means that if one experiences any kind of breakage, repairing it requires expensive splicing tools, which drives up the cost of repair.

2. Light leakage

Additionally, bends in the cable (either over long distances or very tight bends) lead to light leaking out of the optical cable, which reduces both the data bandwidth and the reliability of the signal. Fiber optics require costly upfront investment in equipment and new cable rollout.

3. Fault prevention

Finally, a major challenge with fiber optic cables comes down to fault isolation. Due to the very long transmission window for a fiber optic cable, and the fact that any breakage leads to the cable breaking down completely, isolating a fault in the cable can be very difficult.

While network technicians have tools to help isolate breakages, like OTDR, the high cost of a breakage and the difficulty of fixing existing cables means that fault prevention is extremely important and required for any high-value network.

The future of optical networking

Networked computers are constantly demanding to transfer more data more quickly. The flood of video crossing the internet today has only accelerated this trend.

The explosion of AI-backed computing adds even more fuel to the fire; billions of people now regularly send and receive large amounts of data for text, image, and video generation, both for work and play.

Optical networks have the strength needed to lift the weight of all this data and carry it where it needs to go.