TL;DR: Backbone cabling connects a building’s telecom rooms to each other and to the main equipment room. Horizontal cabling runs from each telecom room out to the individual outlets at desks, cameras and access points. Backbone is few runs carrying aggregated traffic, horizontal is many runs carrying one device each. Getting the split right at design stage is what keeps a building expandable. Our structured cabling team designs both.
Most cabling quotes get compared on price per drop, which hides the decision that actually matters. Two buildings with the same number of outlets can have completely different backbones, and the one with the cheaper backbone is usually the one that runs out of room first. This post explains what each subsystem does and where the money and the risk sit.
What does backbone cabling mean?
Backbone cabling is the cabling that links a building’s distribution points to each other: the main equipment room to each telecom room, and telecom rooms to one another where the design calls for it. It is sometimes called vertical or riser cabling, because in a multi storey building it typically runs up through risers between floors.
The Fiber Optic Association’s reference on TIA-568 premises cabling standards defines it in the standard’s own terms as “cabling between either Distributor A and Distributor C or Distributor B and Distributor C”, which is the hierarchy of distribution points the standard uses in place of the older room based names.
The defining characteristic is aggregation. A backbone run does not serve one device. It carries the combined traffic of everything connected to the telecom room at its far end, which is why it is normally fiber, normally redundant on serious builds, and normally specified with far more headroom than the horizontal runs it feeds.
What is horizontal cabling?
Horizontal cabling is the cabling that runs from a telecom room out to the individual outlets that devices plug into. The FOA reference defines it as “cabling between Distributor A and Equipment Outlet”, meaning the last leg from the distribution point to the wall plate, camera, access point or door controller.
It is called horizontal because on any given floor it runs out across that floor rather than between floors. It is the part most people picture when they imagine network cabling: hundreds of twisted pair runs fanning out above a ceiling into trays and conduit.
Horizontal cabling is where volume lives. A floor might have two or four backbone runs and three hundred horizontal ones, which is why horizontal decisions dominate labour cost and why the category you choose there, covered in our comparison of Cat5e and Cat6, has such a large effect on the total.
What are the key differences between backbone and horizontal cabling?
Backbone cabling connects rooms to rooms and carries aggregated traffic over fewer, higher capacity runs, usually fiber. Horizontal cabling connects rooms to outlets and carries a single device’s traffic over many runs, usually twisted pair copper. Backbone is about capacity and resilience, horizontal is about count and consistency.
The consequences follow from that split. Backbone failures are severe and affect everyone behind them, so they justify redundancy and better media. Horizontal failures affect one outlet, so they justify good labelling and testing rather than redundancy.
The media choice usually differs too. Copper’s distance limits are a real constraint on backbone runs in larger buildings, so fiber is common there, which is why the choice between single mode and multimode fiber is a backbone question rather than a horizontal one. Horizontal runs are short enough that copper is normally the right answer, not least because it carries Power over Ethernet and fiber does not.
Where the two meet is the telecom room, which is why the design of the network closet is not a separate question from the cabling design. The room is where backbone terminates, horizontal originates, and both get patched together.
What is a fiber backbone?
A fiber backbone is backbone cabling built with optical fiber rather than copper. It is the normal choice in commercial buildings because fiber carries far more bandwidth over far greater distances than twisted pair, and because it is immune to the electrical interference that backbone routes often pass through.
Fiber also ages better in the one way that matters for a backbone. Upgrading the electronics at each end can multiply the capacity of an installed fiber without touching the cable, whereas getting more out of copper generally means pulling new copper. On a run that passes through risers, walls and occupied floors, not having to pull it again is worth a great deal.
The practical decisions are strand count and fiber type, and both are easy to under specify. Strands are cheap while the pathway is open and expensive once it is closed, which is the argument for specifying more than the current design needs. Our warehouse fiber backbone case study shows what that looks like on a completed job.
Structured cabling standards and why the names keep changing
Structured cabling standards define these subsystems so that buildings are wired to a common pattern rather than to one contractor’s habits. The naming has shifted over the years, which is a large part of why the terminology in this area is so inconsistent.
The FOA reference sets out the current hierarchy in terms of distributors rather than the older room names, and also describes the cross connect subsystem as “cabling between Distributor A and Distributor B”. Older documents, older installers and plenty of current marketing still use the earlier names, so it is common to see the same cable described three ways on one project.
The point of the standards is not vocabulary, it is interoperability and testability. A building wired to the standard can be tested against a known specification, extended by a different contractor years later, and warranted by a manufacturer. A building wired to somebody’s preference cannot reliably do any of those things, which is the argument behind our post on future proof data wiring.
Designing both in Southwest Florida
For commercial clients across Fort Myers, Cape Coral, Naples, Bonita Springs, Estero and Punta Gorda, we design the backbone and the horizontal together, because the placement of the telecom rooms is what determines how much horizontal cable the building needs in the first place. Move a room, and hundreds of runs get longer or shorter.
Warehouses and multi building sites push this hardest. Distances are long, pathways are shared with equipment, and the backbone often has to leave the building entirely, which is the sort of problem our warehouse network projects are built around.
CommX Networks has spent nearly two decades designing and installing structured cabling, fiber, enterprise wireless and security systems for commercial clients in the region. To talk through a new build, a fit out or an expansion, contact our team, or read more about our network cabling work and the areas we serve.
Frequently asked questions
What is backbone networking?
Backbone networking is the part of a network that carries aggregated traffic between distribution points rather than traffic to and from individual devices. In a building that means the links between telecom rooms and the main equipment room. The backbone cabling is the physical layer those links run over.
Is backbone cabling always fiber?
No, but it usually is in commercial buildings. Copper backbone runs are possible and are still found on small single floor sites, but distance limits and interference make fiber the practical choice once a building has multiple telecom rooms or long routes between them.
Can horizontal cabling be fiber?
It can, and it occasionally is, but copper remains standard for horizontal runs. The main reason is Power over Ethernet: most devices at the end of a horizontal run, including cameras, access points and phones, are powered over the same cable that carries their data, and fiber cannot do that.
Who decides where the telecom rooms go?
It should be decided at design stage by whoever is responsible for the cabling, working from the distance limits and the floor plan, rather than being assigned whatever space is left over. Room placement sets how much horizontal cable the building needs and whether future expansion is possible without new rooms.