A registered jack (RJ) is a standardized physical interfacefor connecting telecommunications equipment (commonly, a telephone jack) orcomputer networking equipment. The standard designs for these connectors andtheir wiring are named RJ11, RJ14, RJ45, etc. These interface standards aremost commonly used in North America, though someinterfaces are used world-wide.
The physical connectors that registered jacks use are of themodular connector type, except RJ21X which is a 25-pair Amphenol connector. Forexample, RJ11 uses a 6 pin 2 conductor (6P2C) modular plug and jack.
TIA/EIA-568-B(RJ45) is a set of three telecommunicationsstandards from the Telecommunications Industry Association, a 1988 offshoot ofthe EIA. The standards address commercial building cabling for telecom productsand services. The three standards are formally titled ANSI/TIA/EIA-568-B.1-2001,-B.2-2001, and -B.3-2001.
The TIA/EIA-568-B standards were first published in 2001. Theysupersede the TIA/EIA-568-A standards set, which are now obsolete.
Perhaps the best known features of TIA/EIA-568-B.1-2001 arethe pin/pair assignments for eight-conductor 100-ohm balanced twisted paircabling. These assignments are named T568A and T568B, and are frequentlyreferred to (erroneously) as TIA/EIA-568A and TIA/EIA-568B
TIA/EIA-568-B defines a hierarchical cable systemarchitecture, in which a main cross-connect (MCC) is connected via a startopology across backbone cabling to intermediate cross-connects (ICC) andhorizontal cross-connects (HCC). Telecommunications design traditions utilizeda similar topology, and many people refer to cross-connects by their older,nonstandard names: "distribution frames" (with the varioushierarchies called MDFs, IDFs and wiring closets). Backbone cabling is alsoused to interconnect entrance facilities (such as telco demarcation points) tothe main cross-connect. Maximum allowable backbone cable distances vary between300 m and 3000 m, depending upon the cable type and use.
Horizontal cross-connects provide a point for theconsolidation of all horizontal cabling, which extends in a star topology toindividual work areas such as cubicles and offices. Under TIA/EIA-568-B,maximum allowable horizontal cable distance varies between 70 m and 90 m fortwisted-pair cable types, depending upon patch cord length and gauge. Fiberoptic horizontal cabling is limited to 90 m. Optional consolidation points ortransition points are allowable in horizontal cables, although many industryexperts discourage their use.
At the work area, equipment is connected to horizontalcabling by patch cords.
TIA/EIA-568-B also defines characteristics and cablingrequirements for entrance facilities, equipment rooms and telecommunicationsroom.
Power over Ethernet or PoE technology describes a system totransmit electrical power, along with data, to remote devices over standardtwisted-pair cable in an Ethernet network. This technology is useful forpowering IP telephones, wireless LAN access points, network cameras, networkhubs, embedded computers, and other appliances where it would be inconvenient,expensive (mains wiring must often be done by qualified and/or licensedelectricians for legal or insurance reasons) or infeasible to supply powerseparately. The technology is somewhat comparable to POTS telephones, whichalso receive power and data (although analog) through the same cable. It workswith an unmodified Ethernet cabling infrastructure.
There are several general terms used to describe thisfeature. The terms Power over Ethernet (PoE), Power over LAN (PoL), and InlinePower are synonymous terms used to describe the powering of attached devicesvia Ethernet ports.
There are several PoE implementations, including ad-hoctechniques, but supplying power over Ethernet according to the IEEE standard isstrongly recommended.