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Old 08-04-2019, 11:12 AM   #1
captainKKK
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Default Do switches have different output distance capabilities?

I have an older 5 Port Cisco switch that works on all five ports connecting computers that are within 10 m but cannot reach a computer at 50 m, on any port. After switching to a different 5 Port switch it has no trouble reaching the 50m computer. Is this normal?
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Old 08-04-2019, 12:46 PM   #2
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Default Re: Do switches have different output distance capabilities?

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I have an older 5 Port Cisco switch that works on all five ports connecting computers that are within 10 m but cannot reach a computer at 50 m, on any port. After switching to a different 5 Port switch it has no trouble reaching the 50m computer. Is this normal?
Assuming 10/100/1000Base, maximum "guaranteed" cable length is 100m.

Switches go bad. As do cables. Verify your connection is actually performing in FDX, etc. before casting a verdict. E.g., swap cable is an easy test.
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Old 08-04-2019, 12:50 PM   #3
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Default Re: Do switches have different output distance capabilities?

I have noticed differences too, I have a link that is significantly too long at around 170m.
With my laptops built in Intel NIC I get a solid 10Mbps connections that I can saturate.
However with an Asus RT-N66U router I can only achieve ca 2Mbps in the same throughput test.
I have been meaning to test some different switches on that link but have not gotten around to it yet...
Of course it could just be bad caps too: https://www.badcaps.net/forum/showpo...38&postcount=6
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Last edited by Per Hansson; 08-04-2019 at 12:52 PM..
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Old 08-04-2019, 03:27 PM   #4
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Default Re: Do switches have different output distance capabilities?

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I have noticed differences too, I have a link that is significantly too long at around 170m.
With my laptops built in Intel NIC I get a solid 10Mbps connections that I can saturate.
However with an Asus RT-N66U router I can only achieve ca 2Mbps in the same throughput test.
I have been meaning to test some different switches on that link but have not gotten around to it yet...
Are you pushing UDP packets or trying to benchmark a TCP connection?

You can query the interface to see what sort of errors it thinks are happening.

But, unless you have a look at the actual signal on the pairs, it's hard to know how much to blame, each device. Could even be kinked cables, etc.

The "easy" solution is a media converter (or even throwing another switch at the midspan).

[I convert to fiber for any longer links -- or anything between buildings, across the yard, etc.]
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Old 08-04-2019, 09:30 PM   #5
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Default Re: Do switches have different output distance capabilities?

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I have an older 5 Port Cisco switch
What is the model number?

Is this a Linksys switch (a division of Cisco)?
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Old 08-06-2019, 02:29 PM   #6
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Default Re: Do switches have different output distance capabilities?

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What is the model number?

Is this a Linksys switch (a division of Cisco)?
Performance issues are often a sign of misconfiguration (PEBKaC) -- duplex mismatching being one of the most common. (e.g., "auto" doesn't always mean "auto"!)

So, swapping (active) EQUIPMENT could make the problem "go away" -- simply because the new piece of kit is serendipitously configured compatibly. OTOH, cables have no configuration information stored in them so swapping a cable will not fix a configuration problem.

I had "issues" with some of the "green" switches when they were first introduced -- much the same as with the "5V only" RS232 transceivers. But, I think most of those problems have evolved their way into obscurity.
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Old 08-12-2019, 10:24 PM   #7
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Default Re: Do switches have different output distance capabilities?

Cisco Small Business SG110D-05
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Old 08-12-2019, 11:42 PM   #8
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Default Re: Do switches have different output distance capabilities?

Doesn't seem right to me. 50 meters should be fine unless you have some heavy interference near to that specific cable, or it's damaged.
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Old 08-13-2019, 02:51 AM   #9
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Default Re: Do switches have different output distance capabilities?

check the voltdrop/resistance of the cable against known good stuff.
or scope it for external interference - if you see some them maybe switch to STP cable.
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Old 08-13-2019, 02:01 PM   #10
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Default Re: Do switches have different output distance capabilities?

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Cisco Small Business SG110D-05
According to Cisco's website, that is a 5 port unmanaged 10/100 switch.

https://www.cisco.com/c/en/us/produc...omparison.html

50 meters should be no problem for this switch. Or any ethernet switch.

Did this switch work before and just die now? Or did you get this used from someone in some unknown state?

And when you say "cannot reach a computer at 50 m", I assume you see no link light on the switch?
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Old 08-13-2019, 02:55 PM   #11
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Default Re: Do switches have different output distance capabilities?

Some switches can tolerate imbalance in the Ethernet cable better than others.
Ethernet cables can get damaged, if the pulls were rough it stretches the cable, or stepped on flat, and ruins the twisted pairs. If the end connections are sloppy, for jacks or wallplates etc. this can also cause problems.
It's important to keep the twisted pairs in tact, no splices in the middle of the run etc. which can cause reflections.

I know IT guys that flip out if you wind up excess Ethernet cable in a loop. It would make a loop antenna adding common-mode noise, but Ethernet shouldn't mind because it can take a lot of common-mode noise assuming the pairs are intact.

Last edited by redwire; 08-13-2019 at 03:29 PM.. Reason: added loop issue
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Old 08-13-2019, 03:43 PM   #12
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Default Re: Do switches have different output distance capabilities?

Ok, smoking gun found. The Cat6 was run through the attic. That wire checked 3 times good. Both end wall plate connectors checked good but replace anyway. Problem remained intermittent, random. ISP modem showed 81 faults in last 40 days, replaced. Problem remained intermittent, random. Ping logs made 24/7. Problem remained intermittent, random. One night, as I was pinging the 50 meter AP, the issue arose......at just the time I heard the A/C come on. Next day, inspection in the attic revealed the Cat6 wire ran right next to the A/C air handler and when it vibrated, the insulation was damaged and grounded by touching the air handler temporarily. Lesson learned, needles in haystacks are hard to find and expensive.
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Old 08-13-2019, 03:48 PM   #13
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Default Re: Do switches have different output distance capabilities?

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Next day, inspection in the attic revealed the Cat6 wire ran right next to the A/C air handler and when it vibrated, the insulation was damaged and grounded by touching the air handler temporarily.
I had a PSTN cable that rested on the exhaust plenum of the furnace. Winter heating would cause the phone to periodically go dead.
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Old 08-13-2019, 11:58 PM   #14
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Default Re: Do switches have different output distance capabilities?

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Lesson learned, needles in haystacks are hard to find and expensive.
Been there and will be there again in the future.

You do learn A LOT though in the process.

Good job finding the problem.
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