C-NNIC cheat sheet

Six structured cabling subsystems: entrance facility, equipment room, backbone cabling, horizontal cabling, telecommunications room, and work area.

Horizontal cabling maximum length is 90 m (295 ft) of permanent link plus 10 m of patch cords for a 100 m channel.

ANSI/TIA-568 recognizes balanced twisted-pair categories 3, 5e, 6, 6A, 8, and multimode/singlemode fiber as horizontal media.

Solid conductor cable is used for permanent horizontal runs; stranded conductor is used for patch cords because of flex life.

T568A and T568B differ only in the pin positions of pairs 2 and 3; both are valid if used consistently at both ends.

A cross-connect in the telecommunications room terminates horizontal cable on a patch panel to allow flexible administration.

Backbone cabling connects entrance facilities, equipment rooms, and telecommunications rooms; recognized media include fiber and multipair copper.

Consolidation point is an interconnection point within horizontal cabling, allowed only in open ceilings or zone boxes, not as a cross-connect.

Star topology dominates structured cabling: every horizontal link home-runs to a telecommunications room, giving single-point fault isolation.

Hierarchical design layers: access (workgroup), distribution (building/floor), and core (campus backbone).

The 100 m channel rule and 90 m permanent link rule set the practical 90 m service radius of a telecommunications room.

Each floor should have at least one telecommunications room; additional rooms are added when the 90 m horizontal distance cannot be met.

Backbone distance limits depend on media: multimode fiber is typically limited by application reach, singlemode by transceiver budget.

Redundant topology (dual core, dual homing) removes single points of failure at the cost of extra cable, pathways, and switch ports.

Point-to-point links are used for backbone and inter-building runs; shared-media bus topologies are legacy and not recommended for new designs.

Separation of voice, data, and building-automation cabling by pathway or by jacket rating reduces EMI and simplifies administration.

Category 6 supports 250 MHz, Category 6A supports 500 MHz, and Category 8 supports 2000 MHz over limited 30 m channels.

Category 6A is specified for 10GBASE-T up to 100 m; Category 6 supports 10GBASE-T only to about 55 m in favorable alien-crosstalk conditions.

Balanced twisted-pair nominal impedance is 100 ohms; coaxial cable used for broadband is typically 75 ohms.

Multimode fiber core sizes are 50/125 and 62.5/125 micrometres; singlemode is 8-10 micrometre core with much lower attenuation.

OM3/OM4 laser-optimized multimode supports 10GBASE-SR to 300 m/400 m and 40/100GBASE-SR to shorter reaches.

Singlemode attenuation is roughly 0.3-0.5 dB/km at 1310/1550 nm; multimode is roughly 3.0-3.5 dB/km at 850 nm.

Shielded twisted pair (F/UTP, S/FTP) provides a foil or braid shield that improves alien crosstalk and EMI immunity versus U/UTP.

Plenum-rated cable (CMP) uses low-smoke, low-flame-spread materials and is required in air-handling spaces; riser (CMR) is used in vertical shafts.

Minimum bend radius: four times the cable outside diameter for UTP during installation, ten times for fiber (varies by count and jacket).

Maximum pulling tension for 4-pair copper is typically 25 lbf (110 N); exceeding it stretches conductors and degrades return loss.

Cable ties should be hook-and-loop or loose; over-cinched ties deform the pair geometry and raise insertion loss and crosstalk.

Fill ratio for conduit is commonly 40 percent of cross-sectional area for new pulls to allow future capacity and reduce friction.

Support horizontal cable at intervals not exceeding 1.5 m (5 ft) and no more than 300 mm from a box or termination.

Separate communications cable from power raceways; maintain at least 300 mm separation from unshielded power lines where practical.

Pathways include conduit, cable tray, J-hooks, raceway, and under-floor ducts; each must be bonded to the telecommunications bonding backbone.

Leave a service loop of about 3 m at the telecommunications room end and 300 mm at the work area for retermination.

Field certification of copper measures insertion loss, return loss, NEXT, PS-NEXT, ACR-F, PS-ACR-F, propagation delay, delay skew, and wire map.

Permanent link test excludes patch cords and uses reference test plugs; channel test includes the user patch cords and is the end-to-end result.

Alien crosstalk (ANEXT/PSANEXT) is measured between adjacent cables and is critical for 10GBASE-T over Category 6/6A.

Wire map faults: open, short, crossed pair, split pair, and reversed pair; a split pair passes continuity but fails NEXT badly.

Fiber tier 1 testing uses an optical loss test set (OLTS) for attenuation and length; tier 2 adds an OTDR trace for event location.

Optical loss budget equals source power minus receiver sensitivity; total link loss is the sum of connector, splice, and fiber attenuation.

Common causes of failing NEXT are untwisted conductors at the termination, excessive jacket removal, and tight cable ties.

Troubleshooting sequence: verify link status, test the patch cord, run the permanent link test, inspect terminations, then replace the run.

ANSI/TIA-568 defines cabling performance and pin assignments; ANSI/TIA-569 covers pathways and spaces; ANSI/TIA-606 covers administration labeling.

ANSI/TIA-607 covers telecommunications bonding and grounding; ANSI/TIA-942 covers data center infrastructure.

NFPA 70 (NEC) Article 800 governs communications circuits; Article 770 covers optical fiber; Article 300 covers wiring methods.

NEC 300.22 restricts cable in air-handling spaces: plenum-rated cable is required in ducts and plenums used for environmental air.

CMP cable is tested for low smoke and flame spread; CMR is for risers; CM/CMG are general-purpose and not for plenum spaces.

Bonding conductor sizing follows TIA-607 and NEC; the telecommunications bonding backbone ties the TMGB to each TGB and to building steel.

OSHA and NFPA 70E require lockout/tagout and PPE when working near energized circuits; laser sources require eye protection and fiber caps.

Labeling per TIA-606 uses a unique identifier for each cable, termination, and pathway, applied at both ends and at cross-connects.

Standard 19-inch equipment rack uses EIA-310 hole spacing; one rack unit (1U) equals 44.45 mm (1.75 in).

Rack-mounted equipment should be supported at both front and rear rails when depth permits; heavy gear goes at the bottom.

Vertical cable managers and horizontal managers preserve bend radius and separate patch cords from power cords.

Power: a rack PDU distributes branch circuits; UPS sizing must cover load in watts, runtime, and power factor.

Cooling: equipment intake air is front-to-back in most racks; arrange racks in hot-aisle/cold-aisle rows to prevent recirculation.

Heat load in watts approximates to BTU/h by multiplying by 3.412; this sizes CRAC/CRAH capacity.

Redundant power uses dual-corded devices on separate A/B feeds from independent PDUs or UPS systems.

Grounding: racks and cable trays bond to the telecommunications bonding backbone; do not use the rack as the only grounding path.