R&M Data Center Handbook

www.datacenter.rdm.com
Thanks to the large headroom with standard lengths, the use of R&M's Cat. 6 A module allows a shortening of the
minimum length as far as down to 2 m. This is sufficient to cover the customarily used lengths in data centers.
required
excess length
required
excess length
On average, the cables between individual server cabinets and the network cabinet need to be 4 to 5 meters of
length, if they are routed from above over a cable guidance system, or 7 to 8 meters if they are routed from below,
through the raised floor. The loops to extend the cables to 15 m are not required when the Class E A/Cat. 6 A solution
developed by R&M is used.
How to measure short permanent links
According to ISO/IEC 11801 / 2 (Table A.5), less stringent requirements are applicable for short 2-connector permanent
links with an insertion loss of less than 12 dB, from 450 MHz on up. Even if the range in question is 450 MHz
and 500 MHz, the field measuring device should always be set to "Low IL". The maximum lowering of the NEXT
requirement is 1.4 dB. Figures below show an example of a measuring arrangement and the results.
Testing of short permanent link (configuration
PL2) with the Fluke DTX 1800 Cable Analyzer.
Test result. The permanent link of 2.1 m in length meets all requirements of
ISO/IEC 11801.
Page 140 of 156 © 08/2011 Reichle & De-Massari AG R&M Data Center Handbook V2.0