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Recently I purchased CAT6 cable with a length of 150 meter. I bought another CAT6 with a length of 148 meter. I joined both the cables using RJ45 cable coupler. I tested it using LAN TESTER, and everything looks normal. One of the end of the cable was connected to ROUTER and the other end was connected to D-Link DES-1005C 5-port 10/100 Mbps Ethernet LAN Network Switch Dlink 5 Port. It also blinks On the network switch when connected. But this is not working. The Pinging always failed. I recheck everything and found that everything was perfectly connected. So looked at the adapter setting, I saw that the Network Connection showed as Unidentified and sometimes it showed as network unplugged, It was blinking plugged and unplugged. How do I solve this? Is there any limit o

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    I would throw away that LAN TESTER.. – user36472 Jul 20 '17 at 16:50
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Per the ANSI/TIA/EIA 568, Commercial Building Telecommunication Standard, UTP cabling is limited to 100 meters. That length assumes up to 90 meters of solid-core (better performance, but fragile) horizontal cable, and no more than 10 meters of stranded (poor performance, but less fragile) patch cord divided between both ends.

Installation is critical, and you must use the same category components throughout a cable run. Each cable run must be tested to meet or exceed all the tests in the test suite for the cable category. Simple connectivity from end-to-end (like for telephone cable) is not sufficient. The high, modern networking frequencies require tight specifications to be met. The primary tests are (see the length in bold):

  • Wire Map - Checks for proper pin to pin termination, and for each of the 8 conductors the wire map checks for: Continuity to the far end, Shorts between any two or more conductors, Reversed Pairs, Split Pairs, Transposed Pairs, Any other miswiring.

  • Length - The physical length of the cable is the actual length derived by measurement of the cable(s) between the two end points. The electrical length is the length derived from the propagation delay of the signal and depends on the construction of the cable. The maximum physical length of the horizontal cable (permanent link) one end of the cable to the other is 90 meters. The maximum length of the channel model is 100 meters.

  • Insertion Loss - Insertion loss is the loss derived from inserting a device into a transmission line. The insertion loss for both the permanent link and the channel models are the total insertion losses of all the components.

  • Near End Cross Talk (NEXT) - Pair to pair NEXT loss is the measurement of signal coupling from one pair to another. The result is based on the worst pair to pair measurement.

  • Power Sum Near End Cross Talk (PSNEXT) - Power sum NEXT takes into account the statistical crosstalk between all pairs while energized. This is a calculated amount derived by adding up the crosstalk results between all pair combinations.

  • Equal Level Far End Cross Talk (ELFEXT) - FEXT is the unwanted coupling of a signal induced by a transmitter at the near end, measured on the disturbed pair at the far end. ELFEXT is the same measurement of FEXT, less the effect of attenuation.

  • Power Sum Equal Level Far End Crosstalk (PSELFEXT) - As in Power Sum NEXT, these are computed values based on the sum of all the possible pair combinations under the respective tests.

  • Return Loss - Return loss is the value of energy reflected by impedance variations when devices are inserted into the cabling system.

  • Propagation Delay - Is the time it takes the signal to travel from one end of the cable/system to the other. The maximum channel propagation delay is 555ns (nanoseconds) and for the link it is 498 ns, both measured at 10 MHz.

  • Delay Skew - Delay skew is the signalling delay difference in time (nanoseconds) between the fastest pair and the slowest pair. The maximum channel delay skew is 50 ns, and in the permanent link it is 44 ns.

Any tests that are out of specification will fail the test, and the condition must be corrected and the test suite performed again until the cable passes or is replaced.

You can also permanently damage a cable by exceeding the pulling tension or minimum bend radius when installing the cable run.

Also, splices, taps, couplers, etc., are not allowed in a cable run.


For Category-6 or above cabling, you should really leave it up to a professional with the experience and proper tools (several thousand dollars), which apparently you do not have. Even experienced installers often have difficulty getting Category-6 or Category-6a cable to pass the test suite.


For cable runs exceeding the 100 meter specification, you use fiber.

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For twisted-pair Ethernet, maximum cable length is 100 m (Cat-6A for 10GBASE-T, Cat-5e for 1000BASE-T or 100BASE-TX, Cat-3 for 10BASE-T). The only exceptions are 2.5G and 5GBASE-T where the maximum length depends on cable grade and and 25GBASE-T or 40GBASE-T which are limited to 30 m (24 m horizontal) over Cat-8. With excessive lengths, the link might still come up (the link pulses for negotiating the link are rather low frequency), but will not actually work reliably.

A cheap LAN tester only tests for continuity, pairing and shorts. For attenuation and NEXT/FEXT you'll need a professional cable tester.

If you need longer links you'll need fiber or plug a switch or an extender in between for regeneration.

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Twisted pair Ethernet is officially limited to 100m. In practice your milage may vary, if you have substandard components or installation it may not reach the full 100m. If you get lucky and things are slightly better than required it may go a little further but either way it's NOT going to go 300m.

So what are your options? there are a few ways you can go.

  1. Break up the link into a number of shorter links with Ethernet switches for regeneration. This is likely the cheapest option if you can get power along the route but it's adding extra points of failure.
  2. Replace the link with fiber. Probablly the best option if replacing the cable is not unreasonablly difficult. You can get pre-terminated fiber to avoid the need for specialist termination equipment.
  3. Run something other than Ethernet. You can get VDSL based extenders (for example https://www.startech.com/uk/Networking-IO/Media-Converters/Ethernet-Extenders/vdsl2-ethernet-over-single-pair-wire-extender-kit~110VDSLEX2GB ) and while they are pretty expensive they may still be cheaper than replacing the cable.
  • I did replace it with fiber. Thanks for the answer. – Mawia HL Mar 6 '18 at 18:11

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