Fiber optics play a huge role in network communications, but it can be a little difficult to understand the basics of fiber optics with all the complex terminology involved.
With the Big Game around the corner, let’s take a look at basic concepts related to fiber optics and transceivers while using analogies from America’s favorite game…football!
Let’s think of the football as data. The objective in football is to move the ball down the field from your field position to the end zone, much like how data transmission is moving data from point A to point B.
In football, teams can move the ball by running or passing the ball. In the data center, data can be moved through two types of mediums: copper cables or fiber optic cables.
Running the ball is like using copper. Both of them work great for shorter distances and are seen as the “traditional” way to get it done.
When it comes to covering longer distances, however, passing plays are more efficient because they can cover more ground in less time. The same idea applies to transmission through fiber.
In fiber optics, data is encoded as light signals (lasers), which are beamed across the fiber. Because light travels faster and with less interference compared to the electrical pulses used by copper, data can be transmitted at a faster rate and over longer distances through fiber. So, if the running game is like using copper, then the passing game would be more like using fiber. Both the passing game and using fiber optics are simply more efficient at longer distances.
A passing play in football involves a player throwing and a receiver catching. Likewise, data transmission between network equipment involves a transmitting device and a receiving device at opposite ends of the fiber. The transmitting device converts the data to light and sends it across the fiber cable to a receiving device, which converts the light signal back to data. These transmitting/receiving devices are called transceivers.
Just like how skill position players are responsible for moving the football up the field, optical transceivers are responsible for moving data from point A to point B. This makes optical transceivers the Peyton Manning’s, Tom Brady’s, Randy Moss’s, of the network communications world. A transceiver using lasers to transmit data to another transceiver is like a quarterback lasering a pass to a wide out for a pass completion.
Transceiver is short for “transmitter-receiver,” which is named as such because transceivers can transmit AND receive data. The two-way connection works in football as well, where players can make both forward as well as lateral passes. Of course, the difference is that only one forward pass is allowed in football, whereas there’s a back-and-forth dynamic between transceivers that makes data transfer more efficient.
The offense must also account for the defense in football. Passing the ball wouldn’t be so difficult if it weren’t for defensive backs like Deion Sanders or Ed Reed trying to break up a pass or lay out a receiver. The main obstacles in network communications, comes in the form of attenuation.
Attenuation is the weakening of signal strength at longer distances caused by obstacles in the signal path. In a fiber strand, which is around the width of a hair strand, small imperfections in the fiber (such as slight bends: microbending/macrobending) can weaken the signal strength of the laser. Much like how a shutdown corner disrupts the passing game and forces the quarterback to have pinpoint accuracy, attenuation makes the job more difficult than it needs to be.
To beat the defense in football, offensive coordinators will gameplay around them by tailoring offensive schemes. Quarterbacks can also call audibles to throw the defense off. Likewise, network engineers will mitigate attenuation by adding amplifiers or repeaters to the mix to boost the signal strength at longer distances. Fortunately, data transmission is much more efficient than even the greatest quarterbacks, otherwise it would take forever to stream any YouTube clip!
Every football player has a unique set of attributes and a specific role on the field. The same goes for transceivers. In football, there are fast players and then there are the really fast players. Likewise, there are transceivers with data rates (amount of data transferred in a unit of time) ranging from 100 megabits per second all the way to the whopping 400 gigabits per second data rates of advanced transceivers.
If you compare it to football players, the 100Mb transceiver is like that tight end who is not particularly fast but blocks really well. The 400Gb transceiver is the All-Pro star receiver who blows by any kind of coverage you throw at him.
Quarterback/receiver combos have their own style of play and utilize the route tree differently. Some quarterbacks prefer to throw short-distance slants, some receivers are better at running mid-distance curl routes and some quarterbacks like to throw the long ball. The same idea applies to transceivers, each of which has a reach specification that indicates how far the lasers can travel.
There are short-reach transceivers more suitable for distances less than 1KM, which may work well in an urban setting where networks are likely to be located closer to each other. There are also long-reach transceivers designed for distances over 80KM, which are more suitable for rural areas with longer distances between networks.
The short-reach, less than 1KM transceiver is like that quarterback who likes to throw short-distance check downs. The long-reach 80KM transceiver is that quarterback who loves airing the long ball out to star receivers on a go route, at any opportunity.
Similar to how we can identify players by their jersey numbers, we can identify transceivers with the help of a naming system. Transceiver nomenclature offers a lot more information than jersey numbers, however, as it is based on the specifications of each transceiver.
Take for example, a transceiver with the name 10GBASE-SR. The transfer rate of the transceiver, in this case 10G, is usually listed at the front. “BASE” means the transceiver is an unfiltered line transceiver, which is standard for most modern transceivers.
The reach of the transceiver is listed at the end of the name, but is usually written as single letters or acronyms, i.e. SR which stands for short reach, LR which stands for long reach, and both ER and ZR which stand for extended reach. T is the label for copper transceivers. So, a transceiver with the name 10GBASE-SR would indicate that it is a short-reach, 10G data rate fiber optic transceiver.
Fiber optic transceivers are also labeled as single-mode and multi-mode transceivers, which indicate the type of cable they are used with. Single-mode cables have a smaller fiber core diameter than multi-mode fiber cables, which allows for lower attenuation.
Most transceivers nowadays are SFPs (Small Form-Factor Pluggables). These are smaller versions of the larger, clunkier GBICs (Gigabit Interface Converter) that used to be commonplace. Datacenters favor more mobile transceivers because network engineers can move them around freely and the devices don’t take up nearly as much space. It is pretty similar to how football has evolved over the years. The game nowadays has more dual-threat quarterbacks who can throw the ball well and have great mobility to scramble if pressured by the defense.
There are also SFP+, QSFP (Quad Small Form-Factor Pluggable) and QSFP+ transceivers. Adding the plus sign to SFP means it has a faster data rate with at least 10Gbps. As its name suggests, QSFP transceivers use four channels and delivers faster data transfer of at least 40Gbps.
Technicians can mix and match different types of transceivers based on network needs. While different networks have different data rate requirements and are separated by a wide range of distances, networks can always count on transceivers to move data from point A to point B. As is the case in football, it’s all about moving the chains.
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To browse Axiom’s full list of network transceivers and cables, please click here.