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Author Topic: Running CAT5 network cable beyond 100 meters  (Read 2593 times)
W0BTU
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« on: November 14, 2009, 03:28:22 PM »

Do you have an experience running CAT5/CAT5e/CAT6 UTP network cable beyond the 'theoretical' 100 meter limit between hubs/routers/switches? If so, I'd appreciate hearing from you.

I found lots of information on the Web that implied that it was probably possible run farther than that, but no personal experiences of anyone who had tried that.

We need to run some cable underground (in PVC conduit) and there's no way to get power to a repeater of any kind.

TIA.
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AA4PB
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« Reply #1 on: November 14, 2009, 04:06:27 PM »

For an underground run between buildings you'd probably be better off running fiber. That's especially true if the buildings use separate electrical system grounds. I have experienced multiple equipment failures when trying to run CAT5 between buildings and it was solved with fiber.

The problem with pushing the 100M limits is that data rates gradually slow due to retries. Its not a simple matter of hooking it up and seeing if it "works" unless you actually measure the throughput that you can obtain. You may get by with a little longer but if you are trying to get 300-400 meters the data rates will likely be slow.
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KG4UPR
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« Reply #2 on: November 15, 2009, 08:16:45 AM »

Better option would be to consider a pair of fiber optic XCVRs. You want 62.5 um multimode. Check Patton Electronics, Black Box, etc. for Ethernet extenders or fiber optic XCVRs/modems.

I don't recommend it, but there have been a couple of cases we exceeded the 100BaseT spec in special circumstances as a last resort. Consider the criticality of the application before proceeding (e.g., business operation, etc.), and the possibility that something working one day out of spec may cease functioning in the future as variables change.

Operating beyond the spec depends on the quality of the cable, end devices, and installation (connector attachment). Test it before installing. If you have a reel or box of cable pull a length exceeding the operational length and install temporary connectors. It might be insightful to characterize the test segment with a cable tester. You could also run a stress test of some kind while observing link performance with an Ethernet sniffer, protocol analyzer, etc. Locking the link to 10Mbps may offer more margin.

KG4UPR
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KG4UPR
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« Reply #3 on: November 15, 2009, 08:22:37 AM »

IIRC, most CAT5/6 is 24 awg, but 22 awg is available (slightly lower attenuation).
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KB3TJT
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« Reply #4 on: November 23, 2009, 03:07:18 PM »

Locking the connection at 10Mbps will definitely help.  Also, stay away from hubs so if there are any errors or retransmits, they will not get broadcast across the whole network segment.  For your application, even a $20 retail store special switch is better than any hub out there.
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W0BTU
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« Reply #5 on: November 27, 2009, 06:19:42 PM »

My thanks to all who replied.

It works just fine at 100Mbs. More details at
http://forums.qrz.com/showthread.php?t=225556

73 Mike
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WA7CC
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« Reply #6 on: November 28, 2009, 09:56:59 AM »

It sounds llike your problem is solved, but if you ever need a good networking reference book, let me recommend "Ethernet: The Definitive Guide" by Charles E Spurgeon.
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