R&M Data Center Handbook

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Frequency IEEE EIA/TIA ISO/IEC
Channel, etc. Channel Components Channel Components
1-250 MHz 1GBase-T Cat. 6 Cat. 6 Class E Cat. 6
1-500 MHz
10GBase-T
IEEE 802.3an
(2006)
Cat. 6A
EIA/TIA 568B.2-
10 (2008)
Cat. 6A
EIA/TIA 568B.2-
10 (2008)
Class E A
ISO/IEC 11801
Appendix 1
(2008)
Cat. 6 A
ISO/IEC 11801
Appendix 2
(2010)
1-600 MHz Class F Cat. 7
1-1000 MHz Class F A Cat. 7 A
Current cabling standards for typical data center requirements
Channel standards in accordance with
EIA/TIA Cat. 6A show a moderate drop of
27 dB in the NEXT curve starting from 330
MHz, while a straight line is defined for the
channel in accordance with ISO/IEC Class
E A.
A design that is in accordance with ISO/IEC
therefore provides for the best possible
transmission performance with maximum
availability in twisted pair copper cabling
based on RJ45 technology. At 500 MHz
the NEXT performance required for Class
E A must be 1.8 dB better than for a Cat. 6A
channel. In practice, this higher demand
leads to higher network reliability, and in
turn to fewer transmission errors.
Comparing IEEE 802.3an, TIA and ISO/IEC: NEXT limit values for channels
This also lays the basis for a longer service and overall life of the cabling infrastructure.
Cable Selection
It is generally known that maximum bandwidth usually also allows a maximum data rate. If cable prices are equal
in terms of length, preference should be given to the cable type of the highest quality (i.e. Category 7 A), unless this
results in clear drawbacks, such as a large outer diameter. This is because this cable category is theoretically
more difficult to install and leads to larger cable routing systems, both of which can increase costs. However, the
experience with many tenders shows that providers very rarely demand an additional price for laying cables of a
higher quality. In addition, the process for planning cable routing systems generally does not differ for Category
7( A) and Category 6(A/ A) media. There is therefore no striking disadvantage when installing top quality cables in
the data center.
In terms of shielding, one must take into account that by using increasingly higher modulation levels, the required
bandwith is certainly reduced, but therefore new protocols are becoming increasingly susceptible to external
electromagnetic influences. The symbol distance of 10 gigabit Ethernet is approximately 100 times smaller than
that of 1 gigabit Ethernet. Nevertheless, unshielded cabling systems can be used for 10GBase-T if appropriate
basic and environmental conditions are satisfied. This is because UTP cabling systems require additional
protective measures to support 10GBase-T, such as:
• Careful separation of data cables and power supply cables or other potential sources of interference
(minimum distance of 30 cm between data and power cables)
• Use of a metallic cable routing system for data cables
• Prevention of the use of wireless communication devices in the vicinity of the cabling system
• Prevention of electrostatic discharges through protective measures common in electronics manufacturing,
like conductor stations, ESD arm bands, anti-static floors, etc.
The effects and costs of additional protective measures as well as operational constraints must also be taken into
consideration when deciding between shielded and unshielded cabling for 10GBase-T.
The EMC (electromagnetic compatibility) behavior of shielded and unshielded cabling systems for 10GBase-T is
described in detail in section 3.10.6, by means of an independent examination.
R&M Data Center Handbook V2.0 © 08/2011 Reichle & De-Massari AG Page 111 of 156