We’re growing around here, and just like when any company grows, more space is needed. Unfortunately, sometimes that space isn’t exactly where you want it. Unlike other companies that just need office space, we need additional space to house our ever growing server farm.
Our servers are neatly organized into server cabinets, sometimes called “racks”. The picture below shows a monitor being connected to one of server cabinets at the Cloudstar data center in New Jersey. The Cabinets sit on top of a “raised floor” from which air conditioned air flows up, keeping the server equipment cool. Entry to the server room is restricted to only those individuals who have a access badge, in combination with the correct finger print. All access is logged, recorded, and archived along with video footage. This works great when all of the cabinets are in a straight line, but what when they’re not? What happens when you need to connect cabinets over long distances? Enter fiber optics.
Under our Jacksonville, Florida data center expansion project, our server cabinets are located on the second floor data center; however we just purchased additional cabinets on the first floor. Let’s think again, how should we connect everything together?
Well, we could use common Ethernet cable, such as this:
That’s the same cable you probably use with your home router, or at the office to connect your computer to the network. While Ethernet cable is an okay solution, it has several flaws. First, it’s made of copper wire which is subject to interference from the other technology we use every day. This includes interference from other wires, radio waves, electricity and other network wiring. This type of interference is called “cross talk” and any kind of interference isn’t a good thing. Second, while not to important in our application, there are distance limitations. Simply put, electrical signals weaken over the length of a long run of copper wire (officially known as attenuation). The better way is to use fiber optic cable.
Fiber optic cable not only benefits us here in the data center world, but it can also benefit YOU, at home, at your office, or in your server room. The problem is, most business owners, don’t know much about fiber optic cable. Here are some basic, beginner level, tips for working with fiber, and selecting the right type of fiber for your particular application.
First off, fiber optic cable is fragile. Be careful not to cause any sharp bends or the core can break leaving you sad and without a connection. Now that we know not to break our fiber, lets learn more about choosing the correct type for our needs.
SINGLE MODE VS MULTI MODE FIBER
Single Mode Fiber is typically used for long distance runs. It is most commonly used by Internet Service Providers and Telephone Companies because of its ability to span long distances. The equipment needed to work with single mode fiber is typically more expensive. This is because the center core of the fiber optic cable is small, and requires more light. In turn, a brighter, more powerful light source is required to use the cable.
Multi-Mode Fiber is commonly used for inter-office deployments and performs better in short distances. It has a larger inner core and can be lit by cheaper, less complex equipment than single mode fiber.
So enough theory, how do we use this stuff? How can we correctly identify the different types of fiber, and how do we connect it?
Single Mode Fiber looks like the picture below, it’s yellow. This is a small piece of single mode fiber that I accidentally ordered which was convenient for the purpose of writing this article.
You’ll note the two white caps at the end of the blue connector. Those are removed before use and exist to keep dirt and dust away from the optical connector. Here at Cloudstar, we use Single Mode fiber for two purposes. First, our various Internet Service Providers deliver Internet Connectivity to us via Single Mode Fiber. Single Mode Fiber Optic cable is provides excellent signal quality so connectivity into our data centers is the best it can be. Additionally, we use Single Mode Fiber to connect the server cabinets from the second floor data center to the first floor data center (which incidentally, is what inspired me to write this article).
Here you can see the Single Mode Fiber existing the cable guard and entering the cabinet. This particular cabinet is new, and currently has no equipment yet.
The next question we need to answer is “how does that fiber optic cable connect into the network”? Most of us understand how our typical copper Cat 5 Ethernet cables connect…. they simply “plug in” to a router or switch. For that to happen with fiber, we need a interface. That interface is called an SFP or (Small Form Factor Plug-gable Transceiver). Of course, they make two types of SFPs, one for Single Mode Fiber, and one for Multi-Mode Fiber. They look identical. Below is a picture of a Multi-Mode Fiber SFP. Notice how the fiber optic cable plugs into the SFP.
Next up is Muli-Mode Fiber. This is actually a great tool to have for both us in the Cloudstar Data Centers, and for you as well. At Cloudstar, we run “two of everything” for redundancy. In the following example, we will show how we can connect two network switches together for redundancy, and do so using Multi-Mode Fiber.
First, we can identify Multi-Mode Fiber by its orange color as we see below.
Again, you’ll notice the two white caps at the end of each connector. Next we will connect each end to an SFP by removing the white caps, and inserting the end of the fiber into the SFP until it clicks. Below, you’ll see the Multi-Mode Fiber with the SFPs on each end.
And finally, we insert the Multi-Mode Fiber into a switch that supports both Ethernet and SFP connections thus connecting both switches.
ADVANCED TIP: For additional redundancy, we will later add TWO fiber cross connects, and aggregate the links from within the control panel of this switch. In this particular setup (2nd link not shown), we have two redundant switches, with redundant link aggregated multi-mode fiber links. This is a great way of adding redundancy to your server room as well.
In summary, there are many real world applications where fiber connectivity can be very useful. Knowing which fiber type to use, which SFP, and which model switching hardware, is necessary to a successful deployment. In many cases, a single run of fiber, with a switch on each end, can save you from having to pull hundreds of copper runs across a building or campus. When stacking switches, fiber up-links are by far superior than copper.
Or course, this is just the beginning. At Cloudstar, we also use fiber (blue multi-mode fiber cable) for connecting storage devices to servers, and utilize all fiber switches such as Brocade switches, to deploy 100% fiber only environments.
The example shown above is an all fiber optic switch, and will out perform any of its copper friends.
In closing, I realize that this can be an advanced topic; however, it’s not one that’s typically talked about. The goal here was to keep things as simple as possible while highlighting some of the basics. If nothing else, I’ll leave you with this:
- Fiber optic cable will deliver you the fastest, cleanest connections.
- Fiber is more reliable than copper
- Fiber is more future proof than copper
- Fiber doesn’t need to be expensive; it can save you money
- A basic understanding is required for a successful deployment