Most fiber projects that go wrong were decided wrongly on paper, months before anyone pulled a cable. The mode was chosen without checking the distance, the connector type was left to whoever supplied the patch cords, or the loss budget was never worked out at all. This guide covers the decisions in the order you actually have to make them.
Single-mode or multimode: decide this first
Everything else follows from this one choice, because it governs the cable, the patch cords and the transceivers at both ends.
Multimode has a wider core, 50 or 62.5 microns, and works with lower-cost optics. It suits links inside a building or across a compact campus. Single-mode has a 9 micron core and carries signal kilometres rather than hundreds of metres, which is why it is used between buildings and for anything approaching carrier distances.
The two cannot be mixed within a link. Single-mode optics fired into multimode fiber produce a link that either fails outright or degrades in ways that are miserable to diagnose. Cable, pigtails, patch cords and transceivers all have to agree.
The multimode grades
- OM1 — 62.5 micron, legacy installations, very limited 10G reach
- OM3 — 50 micron laser-optimised, 10G to around 300 m
- OM4 — 50 micron, 10G to around 400 m, common in newer backbones
- OS1 / OS2 — single-mode, 9 micron, kilometres
For any new backbone expected to carry 10G, OM3 is the sensible floor. Specifying OM1 today saves a little on cable and costs you the upgrade later.
Connectors: LC or SC
SC is the larger push-pull connector, long established and still common on LIU panels and older equipment. LC is roughly half the size, which is why modern switch optics and high-density patch panels use it — twice the ports fit in the same panel width.
Patch cords are named by the connector at each end, so an LC-to-LC cord joins two LC ports and an SC-to-SC cord joins two SC ports. Hybrid LC-to-SC cords exist for connecting newer equipment to older panels.
Ethernet links need duplex cords, carrying a transmit and a receive fiber together.
Where the fiber terminates
An LIU — light interface unit, also called a fiber patch panel or fiber enclosure — is where incoming fiber terminates inside the building. The cable is spliced onto pigtails, those pigtails present as connector ports on the front, and patch cords run from there to the switch.
The LIU does three things worth paying for: it protects the splices, it controls bend radius on the fiber tails, and it gives you a labelled point where the link can be tested. Terminating fiber straight onto equipment without one makes every future fault harder to find.
LIU panels are rack-mounted, so allow for them when sizing the cabinet, along with the slack fiber stored inside. Our racks and cable managers cover the usual configurations.
Splicing or pre-terminated
Fusion splicing joins fiber permanently with very low loss and is the normal way to terminate incoming OFC into an LIU. It needs a splicing machine and a trained technician, so it is a scheduled site activity, not something improvised on the day.
Pre-terminated assemblies arrive with connectors fitted and tested at the factory. They cost more per link but take splicing off the critical path, which suits shorter runs and projects where site access is tight.
The loss budget decides whether it works
This is the calculation most often skipped. Every connector pair and every splice adds attenuation, and a link that looks fine on a drawing can fail once four patch panels sit between the two ends.
Work out the total: cable attenuation over the distance, plus each splice, plus each connector pair, and compare it against the optical budget of the transceivers you plan to use. If the margin is thin, reduce the number of intermediate panels rather than hoping.
When fiber is the right answer
Copper Ethernet stops at 90 metres of permanent link. Fiber carries hundreds of metres on multimode and kilometres on single-mode. It is also immune to electrical interference, and it separates buildings electrically, avoiding the earth-potential problems copper links between structures can create.
- Building-to-building links across a campus or factory
- Backbone risers between floors
- Long runs in warehouses and industrial sites
- Routes passing close to heavy electrical plant
- CCTV links beyond the copper limit — see our CCTV supply page
Within those distances, Cat6 structured cabling remains cheaper to install and terminate, which is why most buildings use fiber on the backbone and copper to the desk.
A checklist before you order
- Measure the route, including vertical runs and slack at both ends
- Choose the mode from that distance, not from habit
- Fix the connector type against the equipment at both ends
- Count cores needed, including spares — pulling a second cable later costs far more than extra cores now
- Decide splicing or pre-terminated, and book the technician if splicing
- Work the loss budget against your transceivers
- Size the rack for the LIU and its slack storage
Fiber supply across Chennai
We supply LC-LC and SC-SC fiber patch cords, and source OFC cable, LIU enclosures, pigtails, adapters and fiber accessories for project requirements across Chennai. Star Networking Services has supplied networking products since 1998, across more than 300 projects for IT companies, hospitals, factories, offices, system integrators and infrastructure contractors.
Send us the route, distance, core count and connector type — or your BOQ — and we will quote the cable, LIU, pigtails and cords as one specification.
See our fiber optic and OFC range, or send your requirement for a quote.