Do the Standards go far enough?

Do the Standards go far enough?Current position and focus of Standards versus what we now know regarding component matching.For some time now we have had ratified standards throughout the world relating to generic, or structured cabling. We have seen progress from the initial Category 3 cable and connectors, to Category 4 albeit very briefly, to Category 5 where we are today. We have also seen a shift of emphasis from component specifications to link and channel specifications which is somewhat more meaningful to the end user. In more recent times we have seen many drafts of Cat. 5, or Cat...
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Do the Standards go far enough?= = === =WHITE PAPER 1 of 4 pages= Do the Standards go far enough?Current position and focus of Standards versuswhat we now know regarding component matching.For some time now we have had ratified standards throughout the world relatingto generic, or structured cabling. We have seen progress from the initial Category3 cable and connectors, to Category 4 albeit very briefly, to Category 5 where weare today. We have also seen a shift of emphasis from component specificationsto link and channel specifications which is somewhat more meaningful to the enduser.In more recent times we have seen many drafts of Cat. 5, or Cat 5e, Category 6and 7. All of these specifications focus heavily on bandwidth, with progressionfrom 16 MHz for Cat 3, to 20 MHz for Cat 4 and for Cat.5 or Cat. 5e still focuseson 100MHz of bandwidth, with some parameters tightened and some newparameters added. Category 6 doubles this bandwidth to 250 MHz, so it is aquantum leap over Cat 5/ Cat 5E. Category 7, if it ever comes to fruition, takes afurther giant leap to 600MHz, however it will be a heavily screened solution withpossibly non-RJ45 connecting hardware.As previously mentioned, we have seen many drafts of both Cat 5e and Cat 6,but the actual ratified published versions seem to be forever coming but neverarriving. In fact, as this paper is being written, we are up to draft 11 of Cat.6! Sowhy the delay? Well, a couple reasons come to mind. Firstly, and mostimportantly, there is an ongoing problem with a relatively new parameter calledreturn loss. Return loss is a signal echo resulting from inconsistencies in thechannel structure, mainly due to poor component impedance matching. Theother reason is that it is no easy feat to produce a Category 6 jack that performsadequately at 250MHz and that remains backwards compatible with Cat 5e patchcords.= = =WHITE PAPER 2 of 4 pagesReturn Loss (RL)Let me come back to the issue of Return Loss (RL). For some time now thestandards bodies have been aware of the problem of poor performance of patchcords when introduced to the basic link (which then becomes the channel). Nowwe have the hard evidence to support this concern.KRONE have identified this problem and the effect on the channel, particularlythe data through-put, through the use of a new test instrument called the Le CroyNewsline. This device has the ability to check both passive and active channels,and when testing active channels has the ability to look at all seven layers of theOSI model.In looking specifically at the passive channel, the Newsline can show anyimpedance anomalies throughout the cabling infrastructure, including the cable,connectors and patch cords. Published standards specify components at 100Ω+/- 15 Ω, which includes cable both solid and stranded, connectors andplug/socket assemblies. The problem comes about from the fact that it appears= = =WHITE PAPER 3 of 4 pages this impedance spread is too broad, resulting in excessive mismatches ofcomponents which affects data throughput on today’s high speed networks. Thediagrams below illustrate this point.All components in the above diagrams are standards compliant, however thereturn loss introduced by the signal reflections seriously distorts data signalsleading to excessive bit error rates (BER’s), resulting in re-transmission of datapackets and an insidious slowing down of your network.This problem often manifests itself when a company upgrades its network from10baseT to 100baseT, which uses more complex and less robust data protocols.The MLT3 encoding used for 100baseT can very quickly degrade due to thesemismatches, resulting in receivers not being able to recognise the signal. CRCerrors become evident and the resultant retransmissions begin to mount. The twodiagrams below are actual traces of the data signal at the transmit end (leftdiagram) and the receive end (right diagram). It’s hard to believe they aresupposed to be the same signal, although the right image would be attenuatedsomewhat in normal circumstances.Tuned Individual Pairs Within The CableKRONE have solved this problem. We have truly matched the cable andconnectors, and also tuned the individual pairs within the cable to ensure amuch tighter impedance spread. The obvious resultant benefit is less return losstherefore less signal degradation, significantly improving network performance.Even the match of the Network Interface Card (NIC) to the cable plant isimproved by this tighter tolerance, often proving to be the saviour of a marginalNIC that may otherwise be discarded and replac ...