1. CABLING SYSTEM
BACKBONE SUBSYSTEM

2. Backbone Subsystem Work Area (WA) Backbone subsystem cables
Cross-connect connecting hardware
Cross-connect

3. CABLING SYSTEM
CABLING SYSTEM

4. 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.

5. 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)

6. Backbone Subsystem

7. 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.

8. Star Topology

9. Non-star ConfigurationsIC HC
Work Area Telecommunications Outlets
Backbone Cabling Subsystem
Level I
Level II
Cabling Subsystem
Horizontal
Optional Backbone Cabling between TRs
MC/IC/HC
IC/HC
HC - Horizontal Cross-connect
IC - Intermediate Cross-connect
MC - Main Cross-connect
Optional Backbone Cabling between ICs

10. Level I Subsystem

11. Level II Subsystem

12. 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.

13. 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.

14. Interconnection
1 The 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.

15. 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.

16. Design Rules
The Backbone cabling subsystem can have only one MC.

17. Design Rules
All HCs are connected with the MC directly or via ICs.

18. Design Rules
No more than one connection center, i.e. IC shall be between any HC and the MC.

19. Design Rules
There may be no more than three connection centers (IC, MC) between any two HCs.

20. Design Rules
Connection centers of the Backbone cabling subsystem can be located in TR, ER, or EF.

21. 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

22. 3 1. Connecting hardware connector in the MC or IC.
Connection Points
3 1. Connecting hardware connector in the MC or IC.
continued on next slide

23. 3 2. Connecting hardware connector in the IC or HC.
Connection Points
3 2. Connecting hardware connector in the IC or HC.

24. 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

25. Connection Points
4 1. Connector of the first unit of connecting hardware in the MC or IC.
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26. Connection Points
4 2. Connector of the second unit of connecting hardware in the MC or IC.
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27. Connection Points
4 3. Connector of the first unit of connecting hardware in the IC or HC.
continued on next slide

28. Connection Points
4 4. Connector of the second unit of connecting hardware in the IC or HC.

29. 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.

30. Application-specific Devices
6 Application-specific devices designed to support specific applications shall not be used as part of the 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.

31. Bridged Taps
7 Twisted-pair bridged taps are not allowed in the Backbone cabling subsystem of the Signamax Cabling System.

32. Splices – TP
2 If 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).

33. 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 of the twisted-pair Backbone cabling subsystem designed to support high-speed applications with maximum allowed 90 m (295 ft) length, because it can degrade link of channel transmission performance.

34. 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.

35. 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) of the 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.

36. 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.

37. 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

38. 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

39. 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

40. 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.

41. 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

42. 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.

43. Distances
The maximum supportable distances in the Backbone cabling subsystem are application and media dependent.
Specific applications may exist, or become available in the 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.

44. 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.

45. 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 over 1 MHz) shall be limited by 100 m (328 ft).

46. Distances
3 The recommended minimum cable length of the category 5e, 6, and 6A twisted-pair Horizontal cabling subsystem is 15 m (50 ft).

47. Cable Slack
4 Making 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)

48. 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

49. 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.

50. Cord Length
1 To 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).

51. 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.

52. 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 of the SCS Manual.

53. TELECOMMUNICATIONS PATHWAYS AND SPACES
CABLING SYSTEM
TELECOMMUNICATIONS PATHWAYS AND SPACES

54. 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.

55. 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.

56. Pathways and Spaces Intra-building Backbone pathways encompass:
Underfloor pathways
Access floor
Conduit
Tray and wireway
Ceiling pathways
Perimeter pathways
Furniture pathways

57. Pathways and Spaces Inter-building Backbone pathways encompass:
Underground
Tunnels
Aerial

58. 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 of the building.

59. Pathways and Spaces
“Other services of the building” in this case means the type of services (for example, power supply, HVAC, water supply, heating, etc.) crucially different from low-voltage/low-current systems, designed for telecommunications purposes in the wide sense of this term (that is, for voice, data and image transmission systems).

60. Pathways and Spaces
16 The use of any open installation methods of the Backbone subsystem cables in public access areas is not allowed.

61. 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.

62. 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.

63. Pathways and Spaces
19 The grounding and bonding system of the Backbone distribution system pathways shall comply with the electrical safety codes and applicable standards.

64. Pathways and Spaces
20 Backbone subsystem pathways shall not be located in elevator shafts.

65. 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.