Published: June 2006
Before any commercial voice/data/video (VDV) network can be placed in service, certification tests must confirm the network meets applicable industry standards. As VDV technologies advance, certification becomes increasingly complex.
To correctly and efficiently perform certification testing, technicians must understand standards and the testing processes and have the testing equipment suited to the types of cabling included in each system. Today, installers work with systems that include twisted copper, coaxial and fiber optic cabling, each with individual testing requirements.
How have certification testers changed since the last Cool Tools report covered them in 2004?
There are two primary trends, said Hugo Draye, Fluke Networks marketing manager for certification products. One is positive, but the other suggests caution.
“On the positive side, certification testers have become more versatile,” said Draye. “New adapters and test modules now let certification tools test coax, single-mode fiber, multimode fiber and even patch cords. The most recent addition is active network testing. Now, the contractor can certify, then test and document that network service has been turned on. This allows contractors to eliminate callbacks, reduce network downtime and expand services to end-users.”
On the cautionary side, Draye said, there are new, low-cost tools entering the market that use the term “certification,” without actually performing the certification tests.
“Typically, these tools simply check the rate at which data can travel across the link,” he said. “Qualification tools, as these types of testers should be called, perform valuable testing, and have their place in qualifying cables and performing fast troubleshooting tasks. But, they are not a substitute for certification, and do not qualify an installation for a cable manufacturer’s warranty.”
Dan Payerle, Ideal Industries product manager for certification, believes the biggest driver of certifier technology has come from western Europe where shielded cabling systems are being integrated and driven to much high frequencies than those used in the United States.
“One driver,” Payerle said, “is the acceptance of broadband over twisted-pair cabling in forward-looking companies and other institutions. Our customers are routinely utilizing our certification testers to test cabling systems up to 1 GHz in current installations.”
While applicable standards ultimately affect what must be tested, advances in technology drive advances in certification testing equipment.
Payerle said power over Ethernet (PoE) is being addressed by new testing configurations, which basically use a modified wiremap test to ignore the pairs that are used to provide direct current (DC) to the PoE device and certify that the remaining pairs are Cat 5e/Cat 6 compliant.
“Regarding 10 GbE [Gigabit Ethernet] applications, Category 6a [augmented] is an emerging cabling standard that is designed to support 10 GbE over a UTP cabling solution,” said Payerle. “The standard requires certification to 500 MHz over a 90m link. There has been some concern regarding the ability of existing installed Cat 6 cabling to support 10 GbE as well.
“The TIA [Telecommunications Industry Association] is addressing this issue with TSB-155 [Technical Service Bulletin-155], which provides an alternative test to recertify existing Cat 6 cabling to support 10 GbE to a channel of 55 meters [180 feet] or less,” he continued. “Ideal has launched a new model in its Lantek family of certifiers, the Lantek6A, which provides 500 MHz testing to certify Cat 6a cabling at the same price as its Lantek6, which has a maximum frequency sweep of 350 MHz.”
Draye cites two major changes for certification tools due to 10 GbE over twisted-pair copper cabling. He, too, cited the frequency range and performance requirements for all certification tests will extend from 250 MHz to 500 MHz to support the much higher data rates of the 10 Gb Ethernet technology.
“Second,” said Draye, “Alien crosstalk test parameters must be included with the field certification effort for 10 Gb Ethernet with focus on the new measurement of alien crosstalk. Crosstalk takes place between wire-pairs in one cable (wire-pairs wrapped in the same sheath). Alien crosstalk is the exact same phenomenon but the crosstalk coupling now occurs between wire-pairs in different, adjacent cabling links.
“Alien crosstalk is the most significant disturbance or noise source for the 10 GbE application when using UTP cabling. Alien crosstalk occurs between every wire in a many-pair bundle, and the combined impact of all wire-pairs in the bundle upon the wire-pair under test (usually referred to as the victim wire-pair) should be assessed. Unfortunately, in most cases it is not economically feasible or affordable to test the alien crosstalk between all possible wire-pair combinations.
“Fluke Networks, in conjunction with leading cabling manufacturers, developed experimental measurement tools and techniques based on the DTX 1800 CableAnalyzer tester, which offers the bandwidth to test crosstalk parameters. The measurement techniques have evolved and are currently used to characterize alien crosstalk parameters in the laboratory as well as in field trials,” Draye continued. “Alien crosstalk modules will be offered with the DTX 1800 when the development cycle is completed.”
In addition, PoE use is becoming more widespread.
“Wireless access points, remote video cameras, and VoIP [voice over Internet protocol] telephones all have data and power requirements,” said Draye. “Using the data cable for both purposes saves installation time and simplifies inevitable changes. But there are implications regarding testing. Current PoE technology has been codified by the publication of the IEEE 802.3af standard, which specifies the operation of Ethernet power-sourcing equipment (PSE) and powered devices (PDs). The specification involves delivering up to 15 watts at a nominal 48 volts DC over unshielded twisted-pair wiring. It works with the existing cable plant, including Category 5, 5e or 6, horizontal and patch cables, patch-panels, outlets, and connecting hardware, without requiring modification.
“The DC voltage on the link is isolated from the high-frequency data signal but it can affect test instruments,” he continued. “Most certification tools perform basic connectivity testing such as wiremap by making DC measurements. The DC voltage generated by the PSE might accidentally trigger protective features in the network test equipment. The simple solution for today is to power down PoE equipment when certifying.
“Longer term, the next generation of certification tools are likely to accommodate PoE as part of the testing process. Parameters such as insertion loss, near end crosstalk, and return loss will only pass if the wiremap is correct. Test equipment manufacturers will likely upgrade testers so that they will automatically detect the presence of PoE and alter the test settings accordingly.”
A new Category 6a standard is coming, possibly before the end of the year, said Payerle. How quickly new equipment is available depends on continuing research and development by manufacturers. He added that tester manufacturers should not want to wait for new standards before reacting, but instead should be in a continuous state of R&D so they can offer products to the market as new technologies emerge.
Regarding new standards, Draye said the IEEE standards for 10 GbE will completed by midsummer of this year. TIA TSB-55 is expected near the end of this year, and the TIA568-B standard is likely to be complete in quarter one or two of 2007.
This updated 568-B standard will push testing bandwidth up to 500 MHz and will include provisions for alien crosstalk. It is also expected that a new standard, TIA568-C, which will include fiber test trace requirements, will likely be completed in the first or second quarter of 2007.
Draye said availability of equipment to meet new standard requirements is expedited by the fact that committees that help write standards include members representing tester and cable manufacturers and installation contractors.
“Manufacturers and installers bring their real-world experience in meeting customer needs to the standards writing body,” he said. “Group consensus helps form workable standards that both advance technology and promote an open-market forum for all manufacturers. Because manufacturers are involved in the discussions, there are usually few surprises, and the reaction to change is fairly quick. More often than not, the more lengthy part of the process is the technical advance itself. By the time the technology settles down, the manufacturers have been involved in the discussions and are ready to bring product to market fairly quickly.”
In conclusion, Draye adds that best practices for cable installation are changing as installers are being asked to perform more services.
It is recommended, he said, that successful technicians follow a three-step process for installing network cable and activating network service:
- Certifying the cabling infrastructure meets TIA/ISO standards requirements
- Verifying network service availability and link connectivity to the network
- Documenting all test results into one consolidated report.
“Ideally an installer should use a tool that can perform both cable certification and network verification tests and produce one report with all results,” Draye said. EC
GRIFFIN, a construction and tools writer from Oklahoma City, can be reached at 405.748.5256 or firstname.lastname@example.org.