I guess the honest answer to the above is, “We’re working on it.” Most manufacturers have products (cable, jacks, patch cords, and test equipment) out in the marketplace promoted in one fashion or another as Category 6 compliant. These products started to enter the marketplace in early 1998 and the list of products and suppliers continues to grow. This is not unusual, nor is it unexpected to those familiar with the industry because the same practice occurred with the standardization of Category 5 and Category 5e. But one still has the right to ask:
• “Where do we stand?”
• “Why is it taking so long?”
• “When will it be finished?”
The standardization process actually began in late 1997 when International Standards Organization (ISO) proposed the objective of a cabling system (Class E/Category 6). The basic objective was to provide the same level of performance, positive attenuation crosstalk ratio (ACR) at twice the frequency (200 MHz) as Category 5 (100 MHz). Easier said than done. Surprisingly, the basic objective stated in late 1997 for the cabling system performance has remained relatively unchanged for the past three and half years.
The most significant change occurred in 1998 when the IEEE asked the TIA and ISO groups to extend the testing out to 250 MHz, even though the performance requirements at 200 MHz did not change. So what is the holdup? It can probably easily be summed up with one word—interoperability—between manufacturers.
Unfortunately, getting from Category 5 to Category 6 has been extremely challenging. Not only does the behavior of the components become more complex as frequencies get higher, our knowledge of what needs to be tested has changed as network protocols become more sophisticated.
Category 5 specifications were based on two-pair applications, such as 10/100Base-T and token ring. Gigabit Ethernet has completely changed the way we view cabling system performance. 1000Base-T is unique in that it uses all four pairs of the cable. Not only that, but each pair transmits and receives simultaneously. To accommodate multi-pair, bidirectional applications like 1000BASE-T, additional parameters have been specified (not only for Category 6 but for Category 5e as well). These parameters are skew, far-end crosstalk (FEXT), power sum crosstalk (PSNEXT and PSELFEXT), and return loss.
It seems that, the more cabling system technology evolves, the more there is to learn. It has been determined that secondary signal reflections—those headed away from the transmitter—are a significant, additional source of noise not accounted for in other parameter measurements. The effect of these reflections shows up as differences between the actual insertion loss (attenuation) of a link or channel and the insertion loss as determined from adding the component losses. This insertion loss deviation (ILD) is taken into consideration in the Category 6 standard.
Another “new” performance parameter involved in the Category 6 standard is balance. Balance refers to the ability of the cabling system to cancel out ambient (common mode) noise picked up from the environment. The requirements for balance are still under discussion and are represented by placeholders in the draft standard.
So, where does the industry stand in the Category 6 development process? What will you get if you install a Category 6 system today? Well, the good news is that the system (channel and link) performance requirements for Category 6 have been stable throughout the development process, and there are no indications that these system specifications will change. But the main issue of interoperability between manufacturers has yet to be resolved.
The biggest issue still facing Category 6 product designers and the standards committee is the connecting hardware and patch cords. The performance of the jack is highly dependent on the plug connected to it. The jacks must be optimized to a certain range of plug performance. What this range will be is still under discussion.
Part of the problem is that the range is so narrow that it is difficult to measure consistently, from lab to lab. Until this issue is resolved, there will be little interoperability between Category 6 products. The problem also affects the manufacturers of field test equipment. Until all Category 6 jacks are tuned to a standard plug, test equipment will have to be provided with multiple test leads, each suitable for particular jacks.
Now that TIA has approved TIA/EIA-568-B.1 and is wrapping up TIA/EIA-568-B.2, the committee will be able to dedicate much-needed time to Category 6. The TIA sent out the latest draft of the Category 6 standard for internal committee ballot in December 2000. They have reviewed the comments in February 2001 and planned to send it out for an industry ballot in March 2001. However, do not expect the standard to be finalized for several months at best. In the meantime, as long as you stick with your system manufacturer of choice and are willing to accept system (channel and link) performance, you will be OK.
Interoperability and support for the local area network (LAN) systems, such as 1000BASE-T, is not the issue. It is the ability to mix-and-match cable and connectivity products, specifically, jacks and patch cords.
BEAM is director of systems marketing at AMP NETCONNECT Systems. He can be reached at (336) 727-5784 or firstname.lastname@example.org.