The increased dependence on reliable network performance has lead to a raft of network testing devices to help spot faults quickly and reduce costly down-time. However, with so many options to choose from – where to begin? Here Guy Shackleton of Ideal Industries offers some advice on when to certify and when to qualify.
The role of certifiers and qualifiers is to confirm that a cable installation has been carried out correctly, and that it meets a certain bandwidth carrying capability. However, these instruments differ in terms of how that is achieved, and which standard the installation is measured against. It’s not always easy to decide which route to take – but much will depend on end user requirements.
For example, a certification tester is the appropriate choice for any installation where proof that structured cabling has been installed correctly and meets standards EN 50173-1, ISO/IEC11801, TIA/EIA-568-B is necessary. These standards define how LANs are designed, installed and tested, and remain the principal points of reference for anyone working on large scale projects.
The standards define various 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 (for example 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.
The standards system, and the full certification testing it demands, is central to maintaining the quality and performance of commercial IT infrastructures, and protecting the interests of network installers and their customers.
A structured cabling system designed and installed in accordance with the standards will support the applications running over it, and will perform well under normal network load conditions. However, this is dependent on the system components being suitable for the job and that the performance of every link has been certified using a certification tester.
Furthermore, system manufacturers will only issue long term warranties if a certification test report is available to prove compliance with EIA/TIA or ISO/IEC standards. So, if an end user wants the support and financial security of a manufacturer’s long term warranty, certification is essential.
Carrying out a full certification test minimises the possibility of call backs, which are not only costly and time consuming, but can also potentially damage the installer’s reputation. The majority of call backs are caused by improperly terminated cables and jacks, so certification testing would eliminate these issues, while also exonerating the installer from blame if damage was caused by another party.
Knowing what’s necessary
When all these issues are added up, it is clear that certification to the standards is absolutely essential for all large scale commercial installations. However, if an installer is working on relatively small scale cabling projects, for example installing networks for small business premises or residential properties, complying with the cabling standards might not be necessary. It could even be seen as an expensive overkill that is actually inappropriate for the type of installation and the end user.
It’s in these situations that qualifiers really come into their own. Qualifiers have been developed to essentially bridge the gap between somewhat basic verifiers and full blown certifiers, enabling a more affordable method of testing bandwidth, while documenting that installations are defect-free and will meet the user’s expectations for quality and reliability.
As well as being considerably less expensive than a certifier, a qualifier will also be easier to use, making it simple to check the network speeds that a cable can support, test every piece of installed cabling, and prove the cabling system works when installed.
Qualifiers test a link’s ability to support applications by transmitting 10/100/1000Mbps Ethernet packets and measuring the link performance and errors according to the IEEE 802.3ab Gigabit Ethernet standard. This simple pass/fail test determines within seconds whether the installed cable can support higher bandwidth applications such as Ethernet or Gigabit Ethernet. This enables an installer to demonstrate to their customer that specific applications will run across the network without any problems.
There are a number of important considerations to make when choosing whether to certify or qualify. Of course, there are the end customer’s requirements, the quality and manufacture of the cabling they choose, whether they require a warranty and how much they want to pay for peace of mind. For the shrewd network professional it is imperative to take the time to fully understand the performance criteria and investigate the various options available, in order to make an informed recommendation to customers.
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