When it comes to designing or upgrading a network, one of the first questions IT teams face is whether to use copper or fiber cabling. The answer? It depends on distance, speed requirements, budget, and sometimes even what’s already in place. But understanding the strengths and limits of each option is key to making the right choice for your infrastructure.
This post breaks it all down: copper categories, fiber types, optics, connectors, and even a few of those small but critical gotchas that can make or break your deployment.
If you’re running an enterprise network, you’re almost certainly dealing with copper cabling in some capacity. And while fiber often steals the spotlight, copper is still very much in the game, especially with advances in multi-gig Ethernet.
You’ve probably encountered the usual suspects: Cat5e, Cat6, and Cat6a. Cat5e is the most common and widely deployed standard, supporting 1Gbps over 100 meters. What often surprises folks is that Cat5e can also handle 2.5Gbps under the right conditions. Cat6 can go up to 5Gbps, and Cat6a reaches 10Gbps at full distance.
It’s important to note that these multi-gig speeds require all four wire pairs in the cable. So if someone in your organization got clever a decade ago and split one Cat5e run into two separate jacks using only two pairs each... well, that cleverness might be coming back to haunt you.
Most structured cabling maxes out at 100 meters, or about 330 feet, for those of us measuring in "freedom units". Knowing your actual cable lengths in either system is key to troubleshooting and planning for proper throughput.
Freedom Unit = not a real thing but we have a little fun here at Matrix with the fact that our standard of measurement here in the US is apparently the right version and that the rest of the world is apparently wrong...
Anyways...
Copper’s still a solid choice for access layer devices, office endpoints, and even access points, particularly now that many wireless standards (like Wi-Fi 6 and 7) demand more than 1Gbps from wired uplinks. We're also seeing more 10Gbps copper switches hit the market, making it easier to get high throughput without jumping to fiber, as long as you're using the right cabling.
Lastly, Direct Attach Cables (DACs), are copper's secret weapon and often overlooked. They are purpose-built for short runs within the same rack. These cables have transceivers built in, making them plug-and-play for connecting switches, servers, or storage inside a cabinet. They’re thick, look more like coax than Ethernet, and are a cost-effective alternative to fiber when distance isn’t a concern, but keep in mind that most top out around 10 meters.
While copper holds its own in many environments, fiber shines when you need high speeds over long distances. And with data centers, warehouses, and multi-building campuses in play, distance often becomes the deciding factor.
Fiber falls into two categories: single-mode and multi-mode.
Single-mode fiber (typically with yellow jackets) is designed for long-range transmission anywhere from 10 to 40 kilometers, depending on your optics. Its tiny 9-micron core allows light to travel in a straight line, reducing signal loss and enabling blazing speeds at extreme distances. Carriers and ISPs rely on it, and it’s the preferred choice for future-proofing infrastructure.
Multi-mode fiber, on the other hand, comes in OM1 through OM4 varieties and is most often seen in orange or aqua jackets. It’s optimized for shorter distances and lower-cost optics. OM1 (often orange) is mostly limited to gigabit speeds and shorter runs. If you’re deploying new fiber today, OM3 or OM4 is the way to go; both offer better support for 10, 40, or even 100Gbps, depending on your optics and environment.
So, when should you choose multi-mode vs. single-mode? If your fiber runs are under 300 meters and budget is a factor, OM3 or OM4 multi-mode can offer excellent performance with less expensive optics. However, if you're planning for long distances or aiming to support future speeds like 100Gbps and beyond, single-mode is the smarter investment.
It might seem like a small detail, but fiber connectors can create big headaches if mismatched. Most modern transceivers use LC connectors, but many legacy patch panels still have SC connectors installed. Before ordering patch cables, always check the fiber termination in your rack. You might need SC-to-LC jumpers to make everything work, and that’s not something you want to discover during a cutover.
When specifying fiber runs, avoid the temptation to install only what you need today. Unlike copper (which comes in pairs), fiber is counted in strands, and it’s best to think ahead. Six-strand is generally the minimum, giving you three usable pairs. Twelve or even twenty-four strands provide room to grow and support redundancy or high-density connections later.
Fiber strands are color-coded in groups of twelve, so scaling up is easier than you might expect. And with newer technologies like BiDi and CWDM/DWDM, you can even run multiple signals down a single strand (if you're using the right optics).
Small Form-Factor Pluggable (SFP) modules are the interface between your switch and your fiber. These little cartridges come in a variety of types, depending on speed and cable type. For example:
SX = Short Reach (multi-mode)
LX = Long Reach (single-mode)
LRM = Long Reach Multi-mode
BiDi = Bidirectional (one fiber strand, two directions)
There are even modules that support DOM (Digital Optical Monitoring), giving you real-time data on light levels for troubleshooting.
Copper and fiber both have strong use cases, and neither is going away anytime soon. The key is understanding what your environment needs and what your cabling can realistically support. Whether you’re running multi-gig over existing Cat5e or lighting up a 10-gig uplink between MDFs, a thoughtful cabling plan can save you time, money, and future headaches.
And hey, just remember: 100 meters is 330 feet... in freedom units.