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Some 20-odd years ago I laid a cable through my house. This backbone is a Cat5 cable. On the cable it says "Verified for gigabit".

Over the years my network has grown and I've recently started reviewing the layout and I need to make some changes (additional cabling and changing routing). This got me wondering if the old cable is still up to spec. But I have no idea how to find that out. I could take it out and replace it for a Cat5e or Cat6. But, that's quite a task.

Question 1: How do I test if the 20 years old "Cat5 verified for gigabit" cable is (still) capable of supporting my LAN at gigabit speed?

Question 2: What symptoms should I be looking out for if the cable is deteriorated?

P.S.: I have two switches (NETGEAR GS105E) in my network that allow me to test the cables, but I think this only tests for impedance and cable breaks. Not sure if those tests are useful in this case.

  • Buy (or borrow) an Ethernet cable tester to be sure. The one linked is only $16. – DavidPostill Jun 24 '17 at 12:20
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    That will not test for speed, just continuity or lack of it. Testing for speed takes a lot more expensive tester - or two computers. – Ecnerwal Jun 24 '17 at 12:27
  • I'd recommend to borrow something more sophisticated or better hire a technician who can handle that. – LotPings Jun 24 '17 at 12:33
  • This may be tested by connecting two PC with crossover cable and send/receive packet in 1GBPS. – Biswapriyo Jun 24 '17 at 12:35
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    The IEEE designed, tested, and specified 1000BASE-T — gigabit Ethernet — to work over 100m runs of plain ol' Cat5 (no 'e'). There's a pervasive myth among networking geeks that it actually requires Cat5e, but that has never been true. It's all there plain as day in the freely downloadable 802.3 spec, but no one seems to bother reading the spec. – Spiff Jun 24 '17 at 17:13
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The practical, affordable test - connect a computer to each end of the cable (or to a switch at each end of the cable.) Basic sanity test - they (or the switch) indicate gigabit connection established over the cable in question.

Transfer large files between them and check the time, or use iPerf, Tamosoft Throughput Test, or some other means of your choice to verify that data moves across the link at something reasonably close to gigabit (may depend on your network adapters, so you might need to check with a short high-quality cable between the computers if you don't get, say, at least 0.8 gigabit throughput between computers.) Some early gigabit ethernet cards can't really keep up, even if they light the light and claim gigabit connection.

Cable sounds like it's "cat5e before there was a cat5e spec" and if so, it should be fine for gigabit. They don't get worse with age unless they are physically abused (hello mice in the walls.)

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