C-NNIC flashcards
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32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Horizontal cabling maximum
- The permanent link from the telecommunications room to the work area is limited to 90 m, leaving 10 m for patch cords to reach a 100 m channel.
- T568A versus T568B
- Both wiring schemes use the same eight pins but swap the positions of pairs 2 and 3. Either is valid if applied consistently at both ends of a link.
- Consolidation point
- An interconnection point inside horizontal cabling, permitted only in open ceilings or zone boxes, that lets a single horizontal run serve a group of work areas.
- Cross-connect purpose
- A cross-connect terminates horizontal or backbone cable on a patch panel so that moves, adds, and changes are made with patch cords rather than retermination.
- Stranded versus solid conductor
- Solid copper is used for permanent horizontal cable because it has lower attenuation; stranded copper is used in patch cords because it withstands repeated flexing.
- Entrance facility
- The space where outside plant cable enters the building and meets internal backbone cabling, including protection devices and demarcation hardware.
- Star topology benefit
- Each horizontal link runs independently to a telecommunications room, so a single cable fault affects only one work area and is easy to isolate.
- Three-tier design model
- Access switches connect end devices, distribution switches aggregate floors or buildings, and core switches carry traffic between distribution blocks at high speed.
- Telecommunications room radius
- Because horizontal permanent links cannot exceed 90 m, each telecommunications room serves a practical radius of about 90 m of cable route.
- Redundant core topology
- Dual core switches with dual-homed distribution switches remove single points of failure, at the cost of extra cabling, pathways, and switch ports.
- Category 6A frequency
- Category 6A balanced twisted pair is characterized to 500 MHz and supports 10GBASE-T to 100 m, with improved alien crosstalk performance over Category 6.
- Category 8 channel limit
- Category 8 is characterized to 2000 MHz but is specified only for channels up to 30 m, typically used in data center switch-to-server links.
- Multimode fiber core sizes
- Common multimode fibers are 50/125 and 62.5/125 micrometres; 50-micrometre laser-optimized OM3 and OM4 support higher speeds over longer reaches.
- Singlemode attenuation
- Singlemode fiber typically loses about 0.3 to 0.5 dB per kilometre at 1310 and 1550 nm, far lower than multimode at 850 nm.
- Plenum versus riser rating
- CMP cable is low-smoke and flame-retardant for air-handling spaces; CMR cable is rated for vertical riser shafts and is not a plenum substitute.
- Shielded twisted pair benefit
- A foil or braid shield around pairs or the cable improves immunity to electromagnetic interference and reduces alien crosstalk between adjacent cables.
- Cable bend radius rule
- Keep bends at least four times the cable diameter for copper during installation and about ten times for fiber, to avoid conductor or glass damage.
- Maximum pulling tension
- Four-pair copper cable is typically limited to 25 lbf (110 N) of pull tension; exceeding it stretches conductors and degrades return loss and crosstalk.
- Conduit fill ratio
- New conduit pulls commonly target no more than 40 percent cross-sectional fill, leaving room for future cable and reducing friction during installation.
- Horizontal cable support interval
- Support horizontal cable at intervals no greater than 1.5 m (5 ft) and within 300 mm of a box or termination to avoid stress and sag.
- Service loop allowance
- Leave roughly 3 m of slack at the telecommunications room and 300 mm at the work area so cable can be reterminated without repulling.
- Permanent link versus channel
- The permanent link excludes user patch cords and tests the installed cable plus terminations; the channel includes patch cords and reflects end-to-end performance.
- Split pair fault
- A split pair occurs when one conductor from each of two pairs is terminated on the wrong pins, passing continuity but causing severe crosstalk.
- Alien crosstalk testing
- ANEXT and PSANEXT measure coupling between adjacent cables rather than within one cable, and are critical for 10GBASE-T over Category 6 and 6A.
- Fiber tier 1 testing
- An optical loss test set measures total attenuation and length of a fiber link, confirming the link meets the loss budget for its application.
- Optical loss budget
- The loss budget is source output power minus receiver sensitivity; the link passes when connector, splice, and fiber losses sum below that value.
- TIA-568 scope
- ANSI/TIA-568 specifies cabling performance categories, pin assignments, and channel distances for commercial building telecommunications cabling.
- TIA-606 administration
- ANSI/TIA-606 defines labeling and recordkeeping for cables, terminations, and pathways, giving every element a unique identifier at both ends.
- NEC Article 800
- NFPA 70 Article 800 covers communications circuits, including permitted cable types, protection, and installation rules for copper communications cabling.
- TIA-607 bonding
- ANSI/TIA-607 specifies the telecommunications bonding backbone and grounding busbars that tie cabling infrastructure to the building grounding electrode system.
- Rack unit height
- One rack unit equals 44.45 mm (1.75 in) in a standard 19-inch EIA-310 rack, and equipment heights are specified as multiples of that unit.
- Watts to BTU per hour
- Multiply equipment heat load in watts by 3.412 to convert to BTU per hour, which is used to size cooling capacity for a room or rack.