Business fiber vs cable: how to compare

The medium matters less than the service sold over it

Cable broadband carries data over a hybrid fiber-coaxial plant using DOCSIS, the specification family published by CableLabs; the fiber-to-the-premises route usually carries it over a passive optical network, where the glass and the splitters between the provider's port and your premises are unpowered. In both cases capacity on the access segment is shared, and in both cases a provider can sell a shared service or a committed one over the same physical plant. That is why the technology name settles very little. A fiber service sold on mass-market terms and a dedicated circuit over the same fiber are different products, and the contract, not the medium, is what distinguishes them.

• Cable runs DOCSIS over a hybrid fiber-coaxial plant; fiber usually runs a passive optical network.
• DOCSIS specifications are published by CableLabs; the PON recommendations are published by ITU-T.
• Shared access capacity is normal on both; a dedicated circuit is a commercial product, not a property of fiber.
• Compare the service definition first and the physical path second.

Upload is where the two usually diverge

Cable's upstream was designed as the lesser direction and still is at the standard level: CableLabs lists DOCSIS 3.1 at up to 10 Gbps downstream but only 1 to 2 Gbps upstream, and describes DOCSIS 4.0 as raising upstream capacity to 6 Gbps while downstream stays at 10 — a large step that is still not equal. Fiber's story is more mixed than the sales line. ITU-T's GPON recommendation and its ten-gigabit successor XGS-PON define shared optical networks, and it is XGS-PON whose title says symmetric; a provider can also sell a symmetric dedicated service over fiber, or an asymmetric shared one. Documented rates are capacity ceilings, not what arrives at your address, which is why the honest test is to list what the business sends — cloud sync, backup, video, cameras, payments, remote access — and compare that against the committed upstream figure in each offer.

• DOCSIS 3.1: up to 10 Gbps downstream, 1–2 Gbps upstream (CableLabs).
• DOCSIS 4.0: up to 10 Gbps downstream, 6 Gbps upstream (CableLabs) — closer to symmetric, still not equal.
• XGS-PON (ITU-T G.9807.1) is defined as symmetric; GPON (G.984.1) is the earlier gigabit class.
• Standards figures are capacity ceilings, not a delivered rate at a given address.

Contention and what happens at the busy hour

Because both a coaxial segment and a passive optical network are shared, the figure that predicts behaviour is not the headline rate but how many premises sit behind the same point and what the network does when they use it at once. On a passive optical network that number is set by the split the provider built; on a coaxial segment it is set by how many subscribers the node serves. Neither is fixed by the standard, which is why the same technology performs differently on two streets. For a business the useful questions are what the busy hour looks like, whether the contract commits a rate through it, and whether your own heavy outbound work — nightly backup, batch processing, security updates that push data out — coincides with when the neighbourhood loads the segment, which for many businesses is exactly when household streaming peaks.

• Ask how many premises share the coaxial segment or the optical split.
• The split ratio is an engineering choice, not a property of the standard.
• A committed rate at the busy hour is worth more than a maximum rate at midnight.
• Check whether your heaviest outbound work runs at the neighbourhood's peak.

Passive and active plant decide where the outages start

Cable and fibre distribute their active electronics differently, and the difference shows up in where an outage begins. A coaxial plant is powered along its length: trunk and distribution amplifiers and fibre nodes are mains-fed from field power supplies, so a power loss at one supply interrupts service for every customer downstream of it, and a node's battery reserve is finite — how long it lasts depends on capacity, load, temperature and age. A passive optical network puts no powered electronics in the outside plant at all: the splitter is unpowered glass, and the equipment that can fail sits at the two ends, in the optical line terminal at the provider's office and the optical network terminal on your wall. The other half of the story is the return path. The coaxial upstream is a shared radio-frequency medium, and CableLabs describes the resulting noise-funnelling problem: ingress from a loose connector, a cracked cable, an unterminated tap or a corroded fitting enters the path and aggregates with everyone else's at the upstream receiver, so one subscriber's defect can degrade the segment. Fibre is dielectric, so it carries no induced signal and provides galvanic isolation, but the electronics at each end still need power and surge protection, and the terminal on your wall still stops when the building loses power.

• Coaxial plant is mains-powered along its length; one failed amplifier or supply takes out everything downstream of it.
• A passive optical splitter has no field power, so the active failure points sit at the provider's terminal and yours.
• Coaxial upstream ingress from one subscriber can degrade others sharing the segment — CableLabs's noise-funnelling problem.
• Fibre is immune to induced interference, but the equipment at each end and your own premises power are not.

What the service level agreement can and cannot promise

A service level agreement is a set of measurable commitments — availability, response and repair times, committed bandwidth, latency and packet loss — with a remedy attached, usually a credit calculated against the charge for the time outside the standard. It is worth reading for what it excludes as much as for what it states. An availability commitment does not guarantee a particular speed at every moment, and it cannot make a shared access segment physically dedicated if it is not. Nor does it usually reach performance across networks the provider does not operate. The distinction that decides most comparisons is between the availability commitment and the bandwidth commitment: a supplier may promise the circuit is up while promising nothing about the rate it delivers, or the reverse. Ask each offer to state both, and to say how each is measured and over what window.

• Availability, repair time, committed bandwidth, latency and loss are separate promises.
• The remedy is usually a credit against the charge, not compensation for the disruption.
• A service level agreement cannot make a shared segment dedicated or guarantee end-to-end performance.
• Ask for the bandwidth commitment separately from the availability commitment.

The upgrade you are promised is not the upgrade you bought

Capacity on an access network is upgraded in place, so the number that matters is not what the plant could carry one day but what it carries now and what the provider has committed to carry. On cable the limit is the diplex split that divides downstream from upstream spectrum: CableLabs describes a mid-split as upstream from 5 to 85 MHz and a high-split as upstream to 204 MHz with downstream beginning at 258 MHz, each expanding the return band from the older 5-to-42 MHz low split. More return spectrum is not more throughput at your address, because throughput also depends on channel width, modulation, how many subscribers share the segment and the operator's own provisioning policy. On fibre the upgrade is a change of line rate rather than of spectrum: ITU-T's GPON runs at roughly 2.488 Gb/s downstream and 1.244 Gb/s upstream across the whole tree, and XGS-PON raises both directions to about 10 Gb/s — aggregate figures shared between every subscriber on the split, not a rate delivered to each one. The contract question is therefore the same for both media: state the current plant capability, the committed rate at the handoff, and, if an upgrade is promised, the technology, the premises it covers, the date and the remedy if it does not arrive.

• Cable upstream is set by the diplex split: 5–42 MHz low split, 5–85 MHz mid-split, 5–204 MHz high-split (CableLabs).
• More return spectrum raises the ceiling on a shared segment, not the rate delivered to your address.
• Fibre upgrades change the shared PON line rate — GPON near 2.488/1.244 Gb/s, XGS-PON near 10/10 Gb/s (ITU-T).
• Put current capability, committed rate, the upgrade commitment and the remedy in the contract, not in a roadmap deck.

The label you are shown already carries the numbers to compare

There is a reason the fields you need are easy to obtain in the United States: they are required disclosures. The Federal Communications Commission requires broadband providers to display a standardised consumer label at the point of sale — on the provider's website, in retail locations and, in the current rules, summarised in a defined way over the telephone — carrying the monthly price with any introductory rate, typical download and upload speeds, latency, data allowance, contract term and early termination fees. The requirement sits in 47 CFR Part 8, and the revised rule took effect on 14 September 2026. Read those fields against each offer rather than trusting a headline speed. For context on what counts as broadband at all, the Commission's 2024 Section 706 report set the fixed benchmark at 100 Mbps download and 20 Mbps upload, replacing the 25/3 benchmark set in 2015 — a floor for the definition of broadband, not a target for a business.

• US providers must display a broadband consumer label at the point of sale (47 CFR Part 8).
• The label carries price, typical download and upload speeds, latency, data allowance, term and early termination fees.
• The FCC's fixed benchmark is 100 Mbps down and 20 Mbps up; it defines broadband, not business need.
• Compare the label fields directly; a headline speed alone is not one of them.

Construction, contracts and what available really means

Availability is a commercial question dressed as a technical one. The network may pass a building without being connected to it, and a new connection can require a survey, a physical build, a permit and consent from whoever controls the building. Where fiber has to be run on utility poles, the work is scheduled under the FCC's pole-attachment rules at 47 CFR 1.1411: the utility surveys, then presents an itemised estimate of the make-ready work, then completes it on a timeline that lengthens with the size of the order. Contract structure follows the construction cost, which is why fiber terms tend to be longer and why early termination provisions may recover part of the build. Read the term, the notice period and the construction-cost language before the availability question is treated as settled.

• Passed, connectable and requires-a-build are three different answers.
• A new route can need a survey, a build, a permit and landlord consent.
• Pole-based work runs on the utility make-ready timeline set in 47 CFR 1.1411.
• Longer terms and cost-recovery clauses go with construction; read them early.

Deciding at your specific address

At a particular address the decision is usually made by constraint rather than preference. If fiber is not connectable, the technology comparison ends. If it is, the questions that separate the options are what the business uploads, how much interruption it can absorb, whether a genuinely separate second path is possible and what term suits how long the business will occupy the site. Resilience deserves its own line: two circuits of the same type sharing the same duct and the same provider are one failure domain, so a coaxial service entering by one route and a fiber service by another can be more valuable together than either alone. Price the arrangement over the life you expect at the address rather than comparing headline monthly figures, and put the committed rate, the service commitment and the term beside each other before choosing.

• If fiber is not connectable, the comparison is over; confirm that first.
• Match the term to how long you will occupy the site.
• A second path is only a second path if it shares no duct, route or provider.
• Compare committed rate, service terms and term together, not headline speed.

What to gather before asking for pricing

Bring the full service address including suite or unit, the number of users and devices, what the business uploads and downloads at peak with the applications behind those figures, anything that must be reachable from outside, whether the site is leased and who controls access, the current service's measured performance and its end date, and the deadline by which any change must be complete. Add any constraint specific to the building, such as a listed facade, a shared riser or a landlord who controls the entry point. This is the same file a supplier needs to price the address rather than guess at it, and it is what makes two offers comparable instead of merely similar.

• Full address, unit detail and any access constraint.
• Peak upload and download, with the applications behind them.
• Any need for publicly reachable addresses.
• Current measured performance, contract end date and change deadline.

PUT THE OPTIONS SIDE BY SIDE

Your comparison checklist

Common questions