One of the most important steps in completing commercial voice/data/video (VDV) system installation is certification that cabling is correctly installed and that the network meets industry performance standards. To accomplish this task, technicians depend on accurate, reliable certification testers.
The capabilities of certification test instruments are driven by changing technology and standards as demand continues for more bandwidth and greater network speed.
“Cabling has been known to cause as many as half of all network failures,” said David Veneski, Fluke Networks, business unit director for certification. “The most thorough testing for network cabling is certification. Cable certification requires trained technicians and specialized test equipment, and it is an expensive process that must be performed because, by certifying the cable network, failures are reduced, and certification is less costly than making repairs.”
Veneski said reducing failures is a crucial financial benefit, especially in challenging economic times. Certification and recertification is future proof of the network infrastructure. It helps limit warranty claims, and it can reduce waste, which always is a good policy.
Standards drive testing
“The Telecommunications Industry Association (TIA) in August 2009 ratified T568 C2 and is used by most all VDV networks,” Veneski said. “The C2 version consolidated all B addendums into one. Some of the key highlights include clarifying the definitions of a test plug consolidation between the categories of connectors. TDR Tier 2 testing is incorporated, which holds the workmanship for the installer to a higher standard. It has been demonstrated in the field that it is much more difficult to get a compliant OTDR [optical time-domain reflectometer] trace than a loss length measurement, but both Tier 1 and Tier 2 are recommended. Tier 1 is required; Tier 2 is optional but highly recommended in this new version.”
TIA also has addressed Ethernet performance outside data centers and office environments with the TIA 862 and TIA 1005-1, Veneski said.
Dan Payerle, Ideal Industries business unit manager, said that, since the introduction of gigabit Ethernet, there has been a debate about how to test fiber. He said that some believed laser or vertical cavity surface emitting laser (VCSEL) sources should be used since most 1-gigabit fiber transceivers used these types of sources. Others thought that light-emitting diodes were the best solution.
“The IEC developed a standard called ‘Information technology—Implementation and operation of customer premise cabling,’ and part three of that document is titled ‘Testing of optical fiber cabling’ [Document number ISO/IEC 14763-3],” Payerle said. “While the document has been around since late 2006, it is only recently that many of its requirements are being implemented into field-testing equipment and procedures.”
Payerle said 14763-3 affects the design of fiber optic testers and defines the launched modal distribution of light into a multimode fiber when using a power meter and light source (PM/LS) to field test installed multimode cabling.
“More simply stated, it defines the shape of a light beam that should be used to test any type of multimode fiber including laser-optimized fiber. The goal is to specify launch conditions that allow testing in the field with the highest level of accuracy and repeatability regardless of the ‘flavor’ of the multimode fiber. With some changes, TIA may adopt IEC 14763-3 for itself to standardize testing equipment for fiber,” he said.
Regarding 10 gigabit Ethernet, Payerle said every owner of a local area network (LAN) cable tester faces the question of whether to make another investment in a new measuring instrument.
“The answer is ‘maybe,’” he said. “It all boils down to what sort of meter is being used until now. But [you will need] a tester that can sweep to 500 MHz and likely one that is capable of testing both fiber and copper.”
Testing copper and fiber
Ideal and Fluke offer accessories to provide such dual capabilities.
Fluke’s Veneski noted that while copper continues to dominate most enterprise cabling infrastructure, fiber is undoubtedly becoming increasingly prevalent.
“To save money,” he said, “it is helpful for installers and contractors to also be able to use their existing copper certification tools to certify fiber cabling in order to minimize capital expenditures. A single user interface increases efficiency, and allows contractors to respond to growing fiber business with minimal training costs. Fluke Networks’ DTX cable analyzer is a cabling certification instrument for both copper and fiber. Simply by using the proper fiber modules and attachments, the DTX is transformed into a fully functional fiber loss-length tester and OTDR that accurately and precisely tests according to the most current industry standards today.”
Ideal’s Payerle said the Ideal Fiber-TEK FDX modules add full Tier 1 standards fiber-certification capability to the LanTEK II certifier.
“Tier 1 certification utilizes a light source and power meter to measure the power loss of optical cabling,” Payerle said. “FiberTEK FDX modules incorporate dual light sources and a wide range power meter to allow testing loss of fiber links as well as to measure the light emitted from active network equipment for troubleshooting. Our earlier generation of LanTEK certifiers will also test fiber, and our SignalTEK-FO multimedia qualification instrument will test to IEEE 802.3.”
Field testing is an important aspect of certification, and Veneski said field certification of twisted-pair cabling for deployment of 10GBASE-T includes two test phases. The first phase certifies the transmission capability and quality of each individual link.
"This phase,” he said, “evaluates all cabling test parameters that are currently specified in the TIA/EIA-568-C document for Cat 6 or in ISO 11801 for Class E. The test limits are identical to the limits for Cat 6 (Class E) up to 250 MHz, but the frequency range of these tests is extended to 500 MHz.”
The second phase is for alien crosstalk (AXT), which is electromagnetic interference that can occur between wires or cables that are closely bundled together.
“Alien crosstalk is a big factor of the successful operation for 10G Ethernet,” Veneski said, “and in the past two years, AXT testing has become more prevalent. Alien crosstalk certification for 10GBASE-T should include sample testing of some links in a bundle to verify compliance with AXT test parameters.”
Veneski said new “augmented” cables define a higher level of performance for the cabling performance as well as for the AXT characteristics of a cabling system.
“Augmented cabling types are being designed to support 10GBASE-T over a full 100 m horizontal channel,” he continued. “The TIA Cat 6A is published within the 568-C.2 standard. The ISO Class EA cabling standard will be published in a new edition of the 11801 standard. New cabling standards require specifications for each component such as cable, each type of connecting hardware components, patchcords, etc., in addition to channel and permanent link specifications.”
Payerle said, from Ideal’s experience, the industry in the United States has not accepted shielded cabling as quickly as predicted.
“However,” he said, “given Ideal’s experience in the European market where shielded cable is far more commonly deployed, our engineering staff is well versed in any necessary changes to tester technology for North America’s eventual adoption.”
Looking ahead, Veneski expects a growing number of network owners and consultants will require OTDR testing to measure fiber loss, especially as stated in the main body of the TIA cabling standard.
Payerle expects “fairly dramatic” changes in certification instruments will result from the TIA adopting IEC 14763-3 standards for fiber testers.
“With an adoption of uniform standards, we will have uniform testers delivering uniform results for fiber testing,” he said. “Power over Ethernet (PoE) presents some challenges to cable testing. New PoE Plus is 45W versus the 15W of standard PoE. That is going to generate additional heat in cable bundles and an increase in insertion loss with the potential for network performance problems. Cables with PoE technology deployed on them may need to be derated in the future.”
GRIFFIN, a construction and tools writer from Oklahoma City, can be reached at firstname.lastname@example.org.