TEST & MEASUREMENT
Qualify or certify? Network Testing By Guy Shackleton, Head of Marketing-EMEA, Ideal Industries Networks
Introduction Anybody involved in network testing, be it as an installer or a network manager, needs to understand the difference between certifying and qualifying a network. Failure to do so could not only result in a poorly functioning network, but could also prevent cable warranties from being issued. While both devices ensure a cable installation has been carried out correctly and that it meets a certain bandwidth carrying capability, they differ vastly in terms of the standards they meet.
Guy Shackleton
discusses the difference between qualifiers
and certifiers and the situations in which only certification will suffice.
Top End At the top end of the scale there is the certification tester, used mainly in large-scale commercial installations such as data centres in which mission- critical and enterprise-grade cabling is crucial. Often within these premises, outages are not acceptable and in many cases, service level agreements drive to 5 or 6 nines of service availability, thus contingencies are in place to ensure 100 percent network uptime. In any downtime situation time is money – for example, for a financial institution a network outage can literally cost many thousands of pounds per second. In this situation, it is imperative to prove that cabling properly met the appropriate standards when installed and to ensure the issuing of the cable manufacturer’s warranty. Certifiers are built to do this job,
ensuring that structured cabling meets EN50173-1, ISO/IEC11801 and TIA/ EIA-568-B. The standards system and the full certification testing it demands is central to maintaining the quality and performance of commercial IT infrastructures, particularly those which are mission critical. Anybody managing these networks, including installers should also therefore have an up-to-date awareness of the current standards.
LAN Standards Standards EN50173-1, ISO/IEC11801 and TIA/EIA-568-B define how LANs are designed, installed and tested, and remain the principal points of reference for anyone working on large-scale projects. They define various
14 NETCOMMS europe Volume III Issue 1 2012
categories or classes of performance for structured cabling systems and describe test procedures that enable installers to certify links against the measurement performance criteria laid down by a given category or class. The categories are defined by the type and number of parameters tested (length, insertion loss, crosstalk, return loss and resistance); the pass/fail limits associated with these measurement parameters; the frequency range over which measurements are made and the required accuracy level of the test equipment. For example, TIA category 6 and
ISO class E define permanent link and channel tests up to 250MHz and require tests to be performed using at least a level III accuracy tester, whereas
for category 5e and class D a lower accuracy tester will suffice and tests are performed to only 100MHz. It is imperative that structured cabling
systems are designed and installed in accordance with these standards in order to support the applications running over it. Providing the system components are suitable for the job and the performance of every link has been certified using a certification tester, the network will perform well under normal network load conditions. Cable qualifiers can then test the impact on the network of adding VoIP phones, IP CCTV cameras, additional users and PCs. Cable certifiers certify the cable can handle different levels of bandwidth, but qualifiers actually
Qualifiers and certifiers differ vastly in terms of the standards they meet.
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