TIA-942-1-2008 《Data Center Coaxial Cabling Specifications and Application Distances》

TIA STANDARD Data Center Coaxial CablingSpecifications and Application DistancesTIA-942-1 March 2008TELECOMMUNICATIONS INDUSTRY ASSOCIATIONANSI/TIA-942-1Approved: March 28, 2008Representing the telecommunications industry inassociation with the Electronic Industries Alliance--```,,,,`,````,`,,,`,```,,,`,``-`-`,,`,,`,`,,`---NOTICETIA Engineering Standards and Publications are designed to serve the public interest through eliminating misunderstandings between manufacturers and purchasers, facilitating interchangeability and improvement of products, and assisting the purchaser in selecting and obtaining with minimum delay the proper product for their particular need. 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THE FOREGOING NEGATION OF DAMAGES IS A FUNDAMENTAL ELEMENT OF THE USE OF THE CONTENTS HEREOF, AND THESE CONTENTS WOULD NOT BE PUBLISHED BY TIA WITHOUT SUCH LIMITATIONS.--```,,,,`,````,`,,,`,```,,,`,``-`-`,,`,,`,`,,`---ANSI/TIA-942-1 TELECOMMUNICATIONS INFRASTRUCTURE STANDARD FOR DATA CENTERS ADDENDUM1–DATA CENTER COAXIAL CABLING SPECIFICATIONS AND APPLICA-TION DISTANCESTable of Contents FOREWORD (ii)1PURPOSE AND SCOPE (1)2NORMATIVE REFERENCES (1)3DEFINITIONS,ACRONYMS AND ABBREVIATIONS,AND UNITS OF MEASURE (1)3.1Definitions (1)3.2Acronyms and abbreviations (1)3.3Units of measure (1)4ADDITIONAL SPECIFICATIONS FOR75-ohm COAXIAL CONNECTORS (2)5MAXIMUM LENGTH OF COAXIAL CABLING FROM THE MDA (2)6FIELD TESTING OF75-OHM COAXIAL CABLING IN DATA CENTERS (2)Annex A(informative)Revised T-1,E-1,T-3,and E-3Circuit Distances (4)A.1.T-1,E-1,T-3and E-3circuit distances (4)A.2.Baluns for E-3and T-3circuits (7)List of TablesTable1:Maximum Coaxial Cable Attenuation (2)Table2:Maximum circuit distances with no customer DSX panel (4)Table3:Reduction in circuit distances for customer DSX panel (5)Table4:Reduction in circuit distances per connection or outlet (5)Table5:Maximum circuit distances for the typical data center configuration (6)Table6:Maximum backbone for the typical data center configuration (6)Table7:Maximum circuit lengths over baluns NOT including insertion loss of baluns (7)Table8:Reduction in maximum circuit length for each1dB insertion loss for a pair of baluns (7)Table9:Reduction in maximum circuit length for each additional twisted pair connection (after the1st two) (7)--```,,,,`,````,`,,,`,```,,,`,``-`-`,,`,,`,`,,`---ANSI/TIA-942-1FOREWORDTIA standards documents are developed within the Technical Committees of the TIA and the standards coordinating committees of the TIA standards board.Members of the committees serve voluntarily and without commission.The companies that they represent are not necessari-ly members of the TIA.The standards developed within the TIA represent a consensus of the broad expertise on the subject.This expertise comes from within the TIA as well as those out-side of the TIA that have an expressed interest.The viewpoint expressed at the time that this standard was approved was from the editors’experience and the state of the art at that time. Users are encouraged to verify that they have the latest revision of the standard.This Addendum has been prepared by the TR-42.1subcommittee and approved by TR-42.1, the TR-42Engineering Committee and the American National Standards Institute(ANSI). There is one informative annex in this Addendum.The annex is not considered a part of this standard.--```,,,,`,````,`,,,`,```,,,`,``-`-`,,`,,`,`,,`---This addendum supersedes certain application distances in TIA-942.ANSI/TIA-942-11PURPOSE AND SCOPEThis Addendum:∙Specifies additional requirements for connectors to be used for 75-ohm coaxial cablingin data centers.∙Specifies testing requirements for 75-ohm coaxial cabling in data centers.∙Provides an allowance for longer horizontal cabling originating from the MDA for coaxialcabling.∙Amends E1,T1,E3,and T3maximum circuit distances specified in Annex A of TIA-942.2NORMATIVE REFERENCESThe following standards contain provisions which,through reference in this text,constitute pro-visions of this Addendum.At the time of publication,the editions indicated were valid.All stan-dards are subject to revision,and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated be-low.ANSI and TIA maintain registers of currently valid national standards published by them.∙ANSI T1.404-2002,Network and customer installation interfaces –DS3and metallic in-terface specification;3DEFINITIONS,ACRONYMS AND ABBREVIATIONS,AND UNITS OF MEASURE3.1DefinitionsThe generic definitions in this clause have been formulated for use by the entire family of tele-communications infrastructure standards.Specific requirements are found in the normative clauses of this Addendum.For the purposes of this Addendum,the following definitions apply.Return loss:A ratio expressed in dB of the power of the outgoing signal to the power of the re-flected signal.3.2Acronyms and abbreviationsBNC bayonet Neill-ConcelmanDSX digital signal cross-connectTNC threaded Neill-Concelman3.3Units of measuredB decibelft feet,footm meterMHz megahertz--```,,,,`,````,`,,,`,```,,,`,``-`-`,,`,,`,`,,`---ANSI/TIA-942-14ADDITIONAL SPECIFICATIONS FOR75-ohm COAXIAL CONNECTORSCoaxial connectors for75-ohm(734and735type)coaxial cables shall meet the requirements of ANSI T1.404and shall additionally meet the following specifications:Characteristic Impedance:75ohmsMaximum insertion loss at1MHz to22.5MHz:0.02dBMinimum return loss at1MHz to22.5MHz:35dBThe Addendum permits the use of either75-ohm TNC or BNC connectors.However,the plug and jack shall be of the same type and BNC connectors are preferred.Note:The revised specifications for coaxial connectors above permit longer distances for E-1, E-3,and T-3circuits than originally specified in ANSI/TIA-942Annex A.Annex A of this Addendum provides revised distances for circuits over75-ohm coaxial cabling. 5MAXIMUM LENGTH OF COAXIAL CABLING FROM THE MDAThe maximum length of horizontal coaxial cabling from the main distribution area shall be300 meters(984ft)for75-ohm coaxial cabling channels including equipment cords and patch cords, and should be no longer than the maximum distance specified in Annex A of this Addendum for the type of applications intended to run over the coaxial cabling.6FIELD TESTING OF75-OHM COAXIAL CABLING IN DATA CENTERSCoaxial cabling shall be tested for:1.Center conductor continuity;2.Shield continuity;3.Impedance(75-ohms);4.Attenuation(less than the maximum specified in table1based on the planned applica-tions for the cable).Table1:Maximum Coaxial Cable AttenuationApplication-Frequency Maximum attenuation from accessprovider DSX to customer equipmentCEPT-1(E-1)-1MHz 3.6dBCEPT-3(E-3)-17.2MHz 6.6dBT-3-22.4MHz 6.9dBCoaxial cabling should be tested to ensure that end-to-end lengths are shorter than the lengths specified for the planned applications–see Annex A.The cable tester should be calibrated for velocity of propagation using a sample length of the cable under test.As an alternative,length may be measured or determined using jacket dis-tance markings.ANSI/TIA-942-1 Note that the maximum lengths and maximum attenuation values provided in this Addendum are end-to-end from access provider DSX panel to customer equipment including coaxial cable patch cords.Additionally,the cabling should be visually inspected for1.Obvious damage to cable(for example,pinched cable,cuts or abrasion that exposes theshield);2.Incorrect bend radii;3.Loose or damaged connectors.3--```,,,,`,````,`,,,`,```,,,`,``-`-`,,`,,`,`,,`---ANSI/TIA-942-14Annex A (informative)Revised T-1,E-1,T-3,and E-3Circuit Distances This annex is informative only and is not part of this Addendum.A.1.T-1,E-1,T-3and E-3circuit distancesThis Annex replaces Clause A.1.1in Annex A of ANSI/TIA-942in its entirety.The following table 2provides the maximum circuit distances for T-1,T-3,E-1,and E-3circuits with no adjustments for intermediate connections or outlets between the circuit demarcation point and the end equipment.These calculations assume that there is no customer DSX panel between the access provider demarcation point (which may be a DSX)and the end equipment.The access provider DSX panel is not counted in determining maximum circuit lengths.Table 2:Maximum circuit distances with no customer DSX panelCircuit typeCategory 3Category 5e,6&6A 734Type Coaxial735Type CoaxialT-1159m (520ft)193m (632ft)--CEPT-1(E-1)116m (380ft)146m (477ft)332m (1088ft)148m (487ft)T-3--146m (480ft)75m (246ft)CEPT-3(E-3)--160m (524ft)82m (268ft)NOTE:The distances shown in table 2are for the specific applications used in data centers and may be different from the distances supported for various appli-cations in TIA-568-B.Repeaters can be used to extend circuits beyond the lengths specified above.These circuit distances should be adjusted for attenuation losses caused by a DSX panel be-tween the access provider demarcation point (which may be a DSX panel)and the end equip-ment.The following table 3provides the reduction caused by DSX panels in maximum circuit distances for T-1,T-3,E-1,and E-3circuits over the recognized media type.--```,,,,`,````,`,,,`,```,,,`,``-`-`,,`,,`,`,,`---ANSI/TIA-942-15Table 3:Reduction in circuit distances for customer DSX panel Circuit typeCategory 3Category 5e,6&6A 734Type Coaxial735Type CoaxialT-111m (37ft)14m (45ft)--CEPT-1(E-1)10m (32ft)12m (40ft)64m (209ft)28m (93ft)T-3--13m (44ft)7m (23ft)CEPT-3(E-3)--15m (50ft)8m (26ft)Maximum circuit distances should be adjusted for attenuation losses caused by intermediate connections and outlets.The following table 4provides the reduction in maximum circuit dis-tances for T-1,T-3,E-1,and E-3circuits over the recognized media type.Table 4:Reduction in circuit distances per connection or outlet Circuit typeCategory 3Category 5e,6,&6A 734Type Coaxial735Type CoaxialT-1 4.0m (13.0ft) 1.9m (6.4ft)--CEPT-1(E-1) 3.9m (12.8ft)2.0m (6.4ft)4.4m (14.5ft) 2.0m (6.5ft)T-3--0.9m (3.1ft)0.5m (1.6ft)CEPT-3(E-3)-- 1.1m (3.5ft)0.5m (1.8ft)In the typical data center,there are a total of 3connections in the backbone cabling,3connec-tions in the horizontal cabling and no DSX panels between the access provider demarcation point and the end equipment:Backbone cabling:∙one connection in the entrance room,∙two connections in the main cross-connect,Horizontal cabling:∙two connections in the horizontal cross-connect,and ∙an outlet connection at the equipment distribution area.This ‘typical’configuration corresponds to the typical data center with an entrance room,main distribution area,one or more horizontal distribution areas,and no zone distribution areas.Max-imum circuit lengths for the typical data center configuration are in the following table 5.These maximum circuit lengths include backbone cabling,horizontal cabling,and all patch cords or jumpers between the access provider demarcation point and the end equipment.--```,,,,`,````,`,,,`,```,,,`,``-`-`,,`,,`,`,,`---ANSI/TIA-942-16Table 5:Maximum circuit distances for the typical data center configurationCircuit typeCategory 3Category 5e,6,&6A 734Type Coaxial735Type CoaxialT-1135m (442ft)184m (603ft)--CEPT-1(E-1)92m (303ft)134m (439ft)305m (1001ft)137m (448ft)T-3--141m (462ft)72m (236ft)CEPT-3(E-3)--153m (503ft)78m (257ft)With maximum horizontal cable lengths,maximum patch cord lengths,no customer DSX,and no zone outlets,the maximum backbone cable lengths for a ‘typical’data center where T-1,E-1,T-3,or E-3circuits can be provisioned to equipment anywhere in the data center are shown in the following table 6.This ‘typical’configuration assumes that the entrance room,main distribu-tion area,and horizontal distribution areas are separate rather than combined.The maximum backbone cabling distance is the sum of the length of cabling from the entrance room to the main distribution area and from the main distribution area to the horizontal distribution area.Table 6:Maximum backbone for the typical data center configuration Circuit typeCategory 3Category 5e,6,&6A 734Type Coaxial735Type CoaxialT-10m (0ft)46m (150ft)--CEPT-1(E-1)0m (0ft)0m (0ft)190m (624ft)29m (95ft)T-3--26m (85ft)0m (0ft)CEPT-3(E-3)--38m (126ft)0m (0ft)These calculations assume the following maximum patch cord lengths in the ‘typical’data cen-ter:-10m (32.8ft)for UTP and fiber in the entrance room,main distribution area,and horizontal distribution area;-5m (16.4ft)for 734-type coaxial cable in the entrance room,main distribution area,and ho-rizontal distribution area;- 2.5m (8.2ft)for 735-type coaxial cable in the entrance room,main distribution area,and horizontal distribution area.Due to the very short distances permitted by category 3UTP cabling and 735type coaxial cable for T-1,T-3,E-1,and E-3circuits,category 3UTP and 735-type coaxial cables are not recom-mended for supporting these types of circuits.Backbone cabling distances can be increased by limiting the locations where T-1,E-1,T-3,and E-3circuits will be located (for example only in the main distribution area or locations served by horizontal cabling terminated in the main distribution area).--```,,,,`,````,`,,,`,```,,,`,``-`-`,,`,,`,`,,`---ANSI/TIA-942-17Other options for supporting circuits further from the entrance room include:∙provisioning circuits from multiplexers or other circuit provisioning equipment located in the main distribution area or horizontal distribution area;∙provisioning circuits using horizontal cabling from the MDA,reducing the number of connections from six to two,and reducing the number of patch cords.A.2.Baluns for E-3and T-3circuitsBaluns permit E-3and T-3circuits to use twisted-pair cabling instead of 75-ohm coaxial cabling.Distances for E-3and T-3circuits over twisted pair cabling depends on a number of factors,in-cluding the electrical characteristics of the baluns,which are beyond the scope of this standard.However,distances for E-3and T-3circuits over twisted-pair cabling using baluns will be consi-derably shorter than the distances for these circuits over 734type coaxial cabling.Taking into account only the attenuation of the cabling and two twisted pair connections,the maximum distances for E-3and T-3circuits with baluns over twisted-pair cabling is:Table 7:Maximum circuit lengths over baluns NOT including insertion loss of balunsCircuit typeCategory 5e Cable &Panels Category 6Cable &Panels Category 6A Cable &Panels T-360.0m (196.8ft)67,8m (222.5ft)69.3m (227.4ft)CEPT-3(E-3)66.2m (217.2ft)74.5m (244.2ft)75.9m (249.1ft)These calculations assume that the baluns are attached directly to the access provider DSX panel,that there is no customer DSX panel,and that there are two twisted-pair connections.The distances above need to be reduced by the following distances for each decibel of insertion loss for the pair of baluns:Table 8:Reduction in maximum circuit length for each 1dB insertion loss for a pair ofbalunsCircuit typeCategory 5e Cable &Panels Category 6Cable &Panels Category 6A Cable &Panels T-310.2m (33.4ft)11.1m (36.6ft)11.4m (37.4ft)CEPT-3(E-3)11.7m (38.3ft)12.8m (41.9ft)13.0m (42.7ft)If the circuit is to pass through more than two connections,the circuit lengths will need to be re-duced as described in table 9.Table 9:Reduction in maximum circuit length for each additional twisted pair connection(after the 1st two)Circuit typeCategory 5e Cable &Panel Category 6Cable &Panel Category 6A Cable &Panel T-3 1.9m (6.3ft) 1.1m (3.5ft) 1.1m (3.5ft)CEPT-3(E-3)1.9m (6.4ft)1.1m (3.5ft)1.1m (3.5ft)--```,,,,`,````,`,,,`,```,,,`,``-`-`,,`,,`,`,,`------` , , ` , ` , , ` , , ` -` -` ` , ` , , , ` ` ` , ` , , , ` , ` ` ` ` , ` , , , , ` ` ` ----```,,,,`,````,`,,,`,```,,,`,``-`-`,,`,,`,`,,`-----```,,,,`,````,`,,,`,```,,,`,``-`-`,,`,,`,`,,`---。