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BACKBONE SUBSYSTEM
Backbone Subsystem
Work Area (WA)
Backbone subsystemcables
Cross-connectconnecting hardware
Cross-connect
CABLING SYSTEM
Backbone Subsystem
• The Backbone cabling subsystem is based on cabling segments, which link such connection centers as Main Cross-Connect, Intermediate Cross-connects, and Horizontal Cross-connects.In these centers Backbone subsystem links are connected with each other thereby forming Backbone subsystem channels that are used to distribute telecommunications services (voice, data, image, etc) to the Horizontal cabling subsystem.
• Backbone cabling subsystem also includes cabling between buildings.
Backbone Subsystem
• The Backbone cabling subsystem consists of the following elements:
– Main Cross-connect (MC)
– Intermediate Cross-connect(s) (IC)
– Horizontal Cross-connect(s) (HC)
– Level I Backbone subsystem connecting MC with IC(s) or with HC(s)
– Level II Backbone subsystem connecting IC(s) with HC(s)
– Backbone cabling segments connecting Entrance Facility (EF) with MC or with IC(s)
– Patch cords connecting the segments of the Backbone subsystem in the MC and IC(s)
Backbone Subsystem
Telephone
Network Printer
Fax
End UserWork Station
PBX
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Patch Panels
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C
19 20 21 22 23 2413 14 15 16 17 187 8 9 10 11 121 2 3 4 5 6
43 44 45 46 47 4837 38 39 40 41 4231 32 33 34 35 3625 26 27 28 29 30
19 20 21 22 23 2413 14 15 16 17 187 8 9 10 11 121 2 3 4 5 6
43 44 45 46 47 4837 38 39 40 41 4231 32 33 34 35 3625 26 27 28 29 30
19 20 21 22 23 2413 14 15 16 17 187 8 9 10 11 121 2 3 4 5 6
43 44 45 46 47 4837 38 39 40 41 4231 32 33 34 35 3625 26 27 28 29 30
19 20 21 22 23 2413 14 15 16 17 187 8 9 10 11 121 2 3 4 5 6
43 44 45 46 47 4837 38 39 40 41 4231 32 33 34 35 3625 26 27 28 29 30
19 20 21 22 23 2413 14 15 16 17 187 8 9 10 11 121 2 3 4 5 6
43 44 45 46 47 4837 38 39 40 41 4231 32 33 34 35 3625 26 27 28 29 30
19 20 21 22 23 2413 14 15 16 17 187 8 9 10 11 121 2 3 4 5 6
43 44 45 46 47 4837 38 39 40 41 4231 32 33 34 35 3625 26 27 28 29 30
Patch Cords
IXI IXI X
End UserTerminal
Equipment
IXI
MainCross-connect
IntermediateCross-connect
HorizontalCross-connect
Consolidation Point
TelecommunicationsOutlet
Level I BackboneCabling Subsystem
Level II BackboneCabling System
Horizontal CablingSubsystem
Level IIBackbone
Cables
Level IBackbone
Cables
HorizontalSubsystemChannels
Topology
• The Backbone cabling subsystem has a star topology with two hierarchy levels.
• Each IC is connected with the MC by means of Level I Backbone subsystem. All links come together in the MC, thereby forming a star.This is the first level of the hierarchy.
• Each HC in its turn is linked with the IC by the Level II Backbone subsystem also forming a star with a single center in the MC.This is the second level of the hierarchy.
Star Topology
IC
MC
IC IC
HCHC HC HC HC
Work Area Telecommunications Outlets
Ba
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Ca
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Su
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Le
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Le
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HC - Horizontal Cross-connect
IC - Intermediate Cross-connect
MC - Main Cross-connect
Ho
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Level I
Level II
HC HC
IC
Non-star Configurations
IC IC
HCHC HC HC HC
Work Area Telecommunications Outlets
Bac
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Cab
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Lev
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Lev
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OptionalBackbone Cabling
between TRs
MC/IC/HC
IC/HC
HC - Horizontal Cross-connect
IC - Intermediate Cross-connect
MC - Main Cross-connect
OptionalBackbone Cabling
between ICs
Level I Subsystem
Building 4Building 3Building 2
Building 1
IC
MC
IC IC
MC - Main Cross-connect
IC - Intermediate Cross-connect
Level I BackboneCabling
Level II Subsystem
Floor 1
Floor 2
Floor 3
IC
HC
HC
HC
IC - Intermediate Cross-connectHC - Horizontal Cross-connect
Level I Inter-buildingBackbone Cabling
Level IIntra-building
Backbone Cabling
Cross- and Interconnection
• In the Main Cross-connect and Intermediate Cross-connects two methods of connecting active equipment to the Backbone cabling subsystem and one method for passive connection between cable segments of the Backbone cabling subsystem are used.
• More details on cross- and interconnection methods are given in “HORIZONTAL SUBSYSTEM” section.
Cross-connection
1 In the Main Cross-connect and Intermediate Cross-connects of the Signamax Cabling System the cross-connection method shall be applied to connect active equipment with multiport connectors to the Backbone cabling subsystem and to provide passive connection between cable segments of the Backbone subsystems.
Interconnection
1The interconnection is allowed in the Main Cross-connect and in the Intermediate Cross-connects of the Signamax Cabling System to connect active equipment with single-port connectors to the Backbone cabling subsystem.
Interconnection
2 Interconnection is not allowed the Main Cross-connect and in the Intermediate Cross-connects of the Signamax Cabling System to enable passive connection between cable segments of the Backbone subsystems.
Design Rules
• The Backbone cabling subsystem can have only one MC.
HC MC/IC
EF/ER/TR
HC
TR
Public Telecommunications Network
Campus Backbone Cabling System
HC
TR
HC
TR
TO WA
TO WA
TO WA
TO WA
Design Rules
• All HCs are connected with the MC directly or via ICs.
TO
TO TO HC
HC
HC
IC
HC
HC
HC
HC
HC
TO TO
TO
MC
IC/HC
Design Rules
• No more than one connection center, i.e. IC shall be between any HC and the MC.
IC
MC
IC IC
HCHC HC HC HC
Work Area Telecommunications Outlets
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HC - Horizontal Cross-connect
IC - Intermediate Cross-connect
MC - Main Cross-connect
Ho
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Level I
Level II
HC HC
IC
Design Rules
• There may be no more than three connection centers(IC, MC) between any two HCs.
IC
MC
IC IC
HCHC HC HC HC
Work Area Telecommunications Outlets
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HC - Horizontal Cross-connect
IC - Intermediate Cross-connect
MC - Main Cross-connect
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Level I
Level II
HC HC
IC
Design Rules
• Connection centers of the Backbone cabling subsystem can be located in TR, ER, or EF.
HC MC/IC
EF/ER/TR
HC
TR
Public Telecommunications Network
Campus Backbone Cabling System
HC
TR
HC
TR
TO WA
TO WA
TO WA
TO WA
Connection Points
3 In the Permanent Link model of the category 5e, 6, and 6A twisted-pair Backbone cabling subsystem intended to support high-rate data applications (with operation frequency range over 1 MHz) no more than 2 (two) connection points (two connectors) may be used:
continued on next slide
Connection Points
3 1. Connecting hardware connector in the MC or IC.
continued on next slide
TR
MC IC
IC HC
TR
Connection Points
3 2. Connecting hardware connector in the IC or HC.
TR
СD (MC) BD (IC)
BD (IC) FD (HC)
TR
Connection Points
4 In the Channel model of the category 5e, 6, and 6A twisted-pair Backbone cabling subsystem intended to support high-rate data applications (with operation frequency range over 1 MHz) no more than 4 (four) connection points (four connectors) may be used:
continued on next slide
Connection Points
4 1. Connector of the first unit of connecting hardware
in the MC or IC.
continued on next slide
TR
MC IC
IC HC
TR
Connection Points
4 2. Connector of the second unit of connecting hardware in the MC or IC.
continued on next slide
TR
MC IC
IC HC
TR
Connection Points
4 3. Connector of the first unit of connecting hardware
in the IC or HC.
continued on next slide
TR
MC IC
IC HC
TR
Connection Points
4 4. Connector of the second unit of connecting hardware in the IC or HC.
TR
MC IC
IC HC
TR
Connection Points
5 In the optical fiber Backbone cabling subsystem the number of connectors shall be limited by
– One connector pair of the connecting hardware in the Main Cross-connect or Interme-diate Cross-connect.
– One connector pair of the connecting hardware in the Intermediate Cross-connect or Horizontal Cross-connect.
– Number of splices based on the overall optical power budget of the channel.
Application-specific Devices
6 Application-specific devices designed to support specific applications shall not be used as part ofthe Backbone cabling subsystem of the Signamax Cabling System, and, in case of application they shall be kept external to the Main and Intermediate Cross-connects.
Bridged Taps
7 Twisted-pair bridged taps are not allowed in the Backbone cabling subsystem of the SignamaxCabling System.
MC IC
Splices – TP
2If the twisted-pair cable segments designed to support low-speed telecommunications applications (with operation frequency range up to 1 MHz) are longer than 90 m (295 ft), splices can be used to connect twisted-pair cable segments in the Backbone cabling subsystem of the Signamax Cabling System.
The number of splices used to join twisted-pair cable segments in the Backbone cabling subsystem of the Signamax Cabling System is not recommended to exceed the number of three (3).
EF
EF IC
TO
TO TO HC
HC
HC
MC
HC
HC
HC
TO TO
TO
HC
II
III
I
Splices – TP
• In the twisted-pair Backbone cabling subsystem splices may be required in the following cases:
– Transition from outdoor to indoor cable in the Entrance Facility.
– Long cable segments to be connected in complex installation conditions or for segments of short factory length.
• It is not allowed to use splices to connect the cables ofthe twisted-pair Backbone cabling subsystem designed to support high-speed applications with maximum allowed90 m (295 ft) length, because it can degrade link of channel transmission performance.
Splices – FO
8 In the optical fiber Backbone cabling subsystem of the Signamax Cabling System optical fiber splices can be used to connect optical fiber cables.
The number of optical fiber splices shall be determined based on the allowed power budget of the optical fiber Backbone link.
Splices – FO
• In the Backbone cabling subsystem optical fiber splices can be required in the following cases:
– Transition from outdoor to indoor cable in the Entrance Facility.
– Transition from thin buffer fibers (250–900 micron) ofthe Backbone cabling subsystem to optical fiber pigtails by means of fusion or mechanic splicing in Cross-connects.
– Long cable segments to be connected in complex installation conditions or for segments of short factory length.
Splices
9 It is not allowed to use optical fiber splitters and mixers in optical fiber cable segments of the Backbone cabling subsystem of the Signamax Cabling System.
Design
• When choosing a layout and designing Backbone cabling subsystem the following factors should be taken into consideration:
– The backbone cabling is expected to serve the needs of building occupants for one or several planning periods, each period spanning three to ten years.
– During each planning period, the backbone cabling design should accommodate growth and changes in service requirements without the installation of additional cabling.The length of the planning period should be based upon the stability and growth of the end user organization.
continued on next slide
Design
– It is generally not possible or economically viable to install backbone cabling for the entire life of the generic cabling system.
Instead the design may be based on current or foreseeable application requirements.
Such short-term selection criteria is often appropriate for building backbone cabling where there is good physical access to pathways.
continued on next slide
Design
– The selection of campus backbone cabling may require a longer term approach than that adopted for the building backbone, particularly if access to pathways is more limited.
This limitation shall be taken into consideration when choosing inter-building Backbone cabling subsystem planning period (usually, longer planning periods are used).
– Each recognized cable has individual characteristics that make it useful in a variety of situations.
A single cable type may not satisfy all end user requirements.The campus backbone cabling should contain the mix of cabling media and cable types necessary to support the desired applications.
continued on next slide
Design
– When future service requirements are not well defined, use "worst case" scenarios when evaluating different backbone cabling alternatives.
The higher the uncertainty, the more flexible the backbone cabling system needs to be.
– When designing Backbone subsystem pathways and cross-connects special attention should be paid to relative position of EMI sources to the telecommunications cabling.
Transmission Media
• The following types of transmission media are allowed in the Backbone cabling subsystem of the Signamax Cabling System:
– category 5e, 6, and 6A four-pair 100-Ohm unscreened cables
– category 5e, 6, and 6A four-pair 100-Ohm screened cables
– category 3 and 5 multipair 100-Ohm unscreened cables
– category 3 and 5 multipair 100-Ohm screened cables
– OM1 (62.5/125-µm), OM2, OM3, and OM4 (50/125-µm) optical fiber multimode cables
– OS1 and OS2 (8-10/125-µm) optical fiber singlemode cables
Transmission Media
• Multipair twisted-pair cables with category 3 and 5 transmission performance are designed to transmit signals of low-speed applications, for example, analog and digital telephony.
Such cables are not subject to certification testing and are not covered by application warranty.
Distances
• The maximum supportable distances in the Backbone cabling subsystem are application and media dependent.
Specific applications may exist, or become available inthe future, that do not operate over the maximum distances specified for the Backbone cabling subsystem.
• The Signamax Cabling System designers are advised to consult the specific standards associated with the planned service, or equipment manufacturers and systems integrators to determine the suitability of the cabling for specific applications.
Distances
• The distance in the Backbone cabling subsystem is a physical cable length (by the outer jacket) between the points of its termination in Cross-connects.
Distances
10 Maximum allowable distances in the Backbone cabling subsystem of the Signamax Cabling System shall be limited by the specifications of anticipated telecommunications applications, provided the cabling system stays within the boundaries of the end-user premises.
Category 5e, 6, and 6A twisted-pair transmission media between MC and HC, IC and HC, or MC and IC, including equipment and patch cords, if the Backbone cabling subsystem is meant to support high-data-rate applications (with operation frequency range over1 MHz) shall be limited by 100 m (328 ft).
Distances
3The recommended minimum cable length ofthe category 5e, 6, and 6A twisted-pair Horizontal cabling subsystem is 15 m (50 ft).
Cable Slack
4Making of cable slack in the Cross-connects is recommended to enable the possibility of future changes in the Backbone cabling subsystem configuration:
• twisted-pair cable – 3 m (10 ft)
• optical fiber cable – 3 m (10 ft)
Cord Length
11 Total length of category 5e, 6, or 6A twisted-pair equipment and patch cords in MC, IC, or HC shall be limited by– in one Cross-connect:
– 5 m (16 ft) for 24-AWG cables
– 4 m (13 ft) for 26-AWG cables
– in both Cross-connects:– 10 m (33 ft) for 24-AWG cables
– 8 m (26 ft) for 26-AWG cables
if the Backbone cabling subsystem is meant to support high-speed applications (with operation frequency range over 1 MHz).
continued on next slide
Cord Length
11 Total length of twisted-pair equipment and patch cords in MC, IC, or HC shall be limited by the distance specifications of anticipated telecommunications applications taking into account 0.2 length de-rating factor for 24-AWG cables and 0.5 length de-rating factor for 26-AWG cables if the Backbone cabling subsystem is meant to support low-speed applications (with operation frequency range up to 1 MHz).
Total length of optical fiber equipment and patch cords in MC, IC, or HC shall be limited by the distance specifications of anticipated telecommunications applications.
Cord Length
1To enable convenient connection of active equipment and increase flexibility, in the Backbone cabling subsystem aimed to support high-speed applications (with operation frequency range over 1 MHz), the total length of equipment and patch cords in Cross-connects may be increased up to
– 25 m (82 ft) for 24-AWG cords,
– 20 m (66 ft) for 26-AWG cords,
if the fixed cable length is not more than 70 m (230 ft).
Installation
12 The Signamax Backbone cabling subsystem shall be installed in full compliance with the requirements, conditions and rules of section “CABLING SYSTEM INSTALLATION” of this Manual.
Protection
14 The telecommunications grounding and bonding, screening, electromagnetic interference (EMI) protection, electromagnetic compatibility (EMC), peak voltage and sneak current protection systems shall be designed and installed in full compliance with the applicable codes and instructions as well as “CABLING SYSTEM PROTECTION” section ofthe SCS Manual.
TELECOMMUNICATIONSPATHWAYS AND SPACES
Pathways and Spaces
• Backbone pathways consist of intra- and interbuilding pathways.
Backbone pathways may be either vertical or horizontal.
Interbuilding backbone pathways extend between buildings.
Intrabuilding backbone pathways are contained within a building.
Pathways and Spaces
• One or more backbone facilities may exist within a building.
A backbone facility is generally formed by vertically stacking teecommunications closets with floor openings between them.
Tie pathways may also exist to install backbone media between telecommunications closets on the same floor.
Pathways and Spaces
• Intra-building Backbone pathways encompass:
– Underfloor pathways
– Access floor
– Conduit
– Tray and wireway
– Ceiling pathways
– Perimeter pathways
– Furniture pathways
Pathways and Spaces
• Inter-building Backbone pathways encompass:
– Underground
– Tunnels
– Aerial
Pathways and Spaces
15 All pathways where the Backbone subsystem cables are installed shall be intended for this purpose and shall not share their space with other services ofthe building.
Pathways and Spaces
• “Other services of the building” in this case means the typeof services (for example, power supply, HVAC, water supply, heating, etc.) crucially different from low-voltage/low-current systems, designed for telecommunications purposes inthe wide sense of this term (that is, for voice, data and image transmission systems).
Pathways and Spaces
16 The use of any open installation methods of the Backbone subsystem cables in public access areasis not allowed.
Pathways and Spaces
17 The Backbone distribution system pathways shall be designed and installed in compliance with local and national construction regulations and electrical safety codes.
Pathways and Spaces
18 The Backbone pathway characteristics shall adhere to minimum allowable cable bend radius values under load and no-load conditions specified by a cable manufacturer or rules of the SCS Manual.
Pathways and Spaces
19 The grounding and bonding system of the Backbone distribution system pathways shall comply withthe electrical safety codes and applicable standards.
Pathways and Spaces
20 Backbone subsystem pathways shall not be located in elevator shafts.
Pathways and Spaces
21 All rules given in subsection “5.3 Telecommunications pathways and spaces” of section “HORIZONTAL SUBSYSTEM” of this Manual and the ones relating to design and installation of telecommunication distribution systems shall be followed for Backbone cabling subsystem.
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