I need a device that can sit midspan (at a "splice point") and monitor
an ethernet connection for integrity. At the very least, that continuity exists to both ends of the span.

While these are PoE/PoE+ drops, I don't want to place any significant
burden on the PSEs; an external power supply is therefor likely.

I can tolerate brief interruptions in traffic (e.g., during "testing")
and even continuity (less desirable but tolerable as the testing is
only sporadic)

Active, in-line solutions are complicated by power delivery over the pairs.
So, I'm wondering if I could passively monitor signals coming in/out and communicate that status through a different channel?

Cost isn't too critical. Though physical size might be. (the wet-dream ideal would be something that could fit in a 8P8C coupler)

--- SoupGate-Win32 v1.05
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"Don Y" <[email protected]d> wrote in message news:1020c8h$2oq18$[email protected]...

I need a device that can sit midspan (at a "splice point") and monitor
an ethernet connection for integrity. At the very least, that continuity exists to both ends of the span.

While these are PoE/PoE+ drops, I don't want to place any significant
burden on the PSEs; an external power supply is therefor likely.

In that case I'd just put an unmanaged four port non PoE switch at mid run and look into getting access to the LEDs on the switch
which tell me what the link is doing.
The last design I did which had an ethernet port used KS8721BL

I can tolerate brief interruptions in traffic (e.g., during "testing")
and even continuity (less desirable but tolerable as the testing is
only sporadic)

Active, in-line solutions are complicated by power delivery over the pairs. So, I'm wondering if I could passively monitor signals coming in/out and communicate that status through a different channel?

Cost isn't too critical. Though physical size might be. (the wet-dream ideal
would be something that could fit in a 8P8C coupler)

--- SoupGate-Win32 v1.05
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On 6/7/2025 9:11 AM, Edward Rawde wrote:

"Don Y" <[email protected]d> wrote in message news:1020c8h$2oq18$[email protected]...

I need a device that can sit midspan (at a "splice point") and monitor
an ethernet connection for integrity. At the very least, that continuity
exists to both ends of the span.

While these are PoE/PoE+ drops, I don't want to place any significant
burden on the PSEs; an external power supply is therefor likely.

In that case I'd just put an unmanaged four port non PoE switch at mid run and
look into getting access to the LEDs on the switch
which tell me what the link is doing.
The last design I did which had an ethernet port used KS8721BL

But that assumes the cables into and out of the switch are intact
and correctly made. (see my reply to JW)

--- SoupGate-Win32 v1.05
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On 6/7/2025 8:27 AM, John R Walliker wrote:

On 07/06/2025 04:38, Don Y wrote:

I need a device that can sit midspan (at a "splice point") and monitor
an ethernet connection for integrity.  At the very least, that continuity >> exists to both ends of the span.

Do you need to read the data in the signals or just know that there is activity
each way?  The latter would be a lot easier.

I'm trying to address the case where a cable has been "extended"
after initial installation. Expect some "local talent" (of ducious
ability) to have made the modifications.

I want to verify that the "assembly" was made properly (correct pinout)
in each direction from that coupler. And, that the coupler, itself,
was intact. I'm not looking to "qualify" the connection; just
verify that it "should" work -- or not.

I'm debating whether or not the coupler should, in fact, *act* as the interconnect or just monitor it.

Note that the far/device end of the drop may not be operational
if the coupler has been incorrectly made -- it may not be possible
to communicate with it (from the near end/switch) or it may not
even be powered (PoE).

As I only need to do this sporadically, I can tolerate the link to the
far device being down during the testing. But, the kit doing the testing
can't interfere with normal operation of the link (including power
signalling and delivery)

--- SoupGate-Win32 v1.05
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Edward Rawde <[email protected]d> wrote:

"Don Y" <[email protected]d> wrote in message news:1020c8h$2oq18$[email protected]...

I need a device that can sit midspan (at a "splice point") and monitor
an ethernet connection for integrity. At the very least, that continuity exists to both ends of the span.

While these are PoE/PoE+ drops, I don't want to place any significant burden on the PSEs; an external power supply is therefor likely.

In that case I'd just put an unmanaged four port non PoE switch at mid run and look into getting access to the LEDs on the switch which tell me what
the link is doing.
The last design I did which had an ethernet port used KS8721BL

Won't that prevent PoE passing through the link? This switch will terminate the PoE and won't pass power or PoE signalling through to the far end.

I suppose you could have some kind of relay box that normally passes the
line through but interposes an ethernet switch (or something else) in the middle for testing purposes. When you're in test mode the PoE drops, but
maybe you don't mind that. Or maybe you do a PoE receiver and PoE injector
to let PoE pass the tester switch. Some switches can do pair tests: https://www.engineerkhan.com/networking/testing-an-ethernet-cable-from-a-cisco-switch/

Don't know what a relay would do to signal integrity though.
(it probably has to be mechanical due to isolation requirements)

Theo

--- SoupGate-Win32 v1.05
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"Theo" <[email protected]> wrote in message news:lKm*[email protected]...

Edward Rawde <[email protected]d> wrote:

"Don Y" <[email protected]d> wrote in message news:1020c8h$2oq18$[email protected]...

I need a device that can sit midspan (at a "splice point") and monitor
an ethernet connection for integrity. At the very least, that continuity >> > exists to both ends of the span.

While these are PoE/PoE+ drops, I don't want to place any significant
burden on the PSEs; an external power supply is therefor likely.

In that case I'd just put an unmanaged four port non PoE switch at mid run >> and look into getting access to the LEDs on the switch which tell me what
the link is doing.
The last design I did which had an ethernet port used KS8721BL

Won't that prevent PoE passing through the link? This switch will terminate the PoE and won't pass power or PoE signalling through to the far end.

Yes you're right a PoE passthrough switch would be needed. https://www.google.com/search?&q=poe+passthrough+switch&udm=2

I suppose you could have some kind of relay box that normally passes the
line through but interposes an ethernet switch (or something else) in the middle for testing purposes. When you're in test mode the PoE drops, but maybe you don't mind that. Or maybe you do a PoE receiver and PoE injector to let PoE pass the tester switch. Some switches can do pair tests: https://www.engineerkhan.com/networking/testing-an-ethernet-cable-from-a-cisco-switch/

Don't know what a relay would do to signal integrity though.
(it probably has to be mechanical due to isolation requirements)

Theo

--- SoupGate-Win32 v1.05
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On 6/8/2025 6:52 AM, Theo wrote:

Edward Rawde <[email protected]d> wrote:

"Don Y" <[email protected]d> wrote in message news:1020c8h$2oq18$[email protected]...

I need a device that can sit midspan (at a "splice point") and monitor
an ethernet connection for integrity. At the very least, that continuity >>> exists to both ends of the span.

While these are PoE/PoE+ drops, I don't want to place any significant
burden on the PSEs; an external power supply is therefor likely.

In that case I'd just put an unmanaged four port non PoE switch at mid run >> and look into getting access to the LEDs on the switch which tell me what
the link is doing.
The last design I did which had an ethernet port used KS8721BL

Won't that prevent PoE passing through the link? This switch will terminate the PoE and won't pass power or PoE signalling through to the far end.

Yes. And, the switch will have to signal to the PSE that it is present
in order to receive power (even if the PD is NOT) and then mimic the
state of the PD after the testing is complete.

An active solution also has to preserve transit times (or, at least
represent a constant delay across the switch for timing-sensitive
protocols)

I suppose you could have some kind of relay box that normally passes the
line through but interposes an ethernet switch (or something else) in the middle for testing purposes. When you're in test mode the PoE drops, but maybe you don't mind that. Or maybe you do a PoE receiver and PoE injector to let PoE pass the tester switch. Some switches can do pair tests: https://www.engineerkhan.com/networking/testing-an-ethernet-cable-from-a-cisco-switch/

You're not just looking for a failed conductor/pair but, also, miswired pairs. Using a switch (or even a 1-port router) means you expect the connections to
it to be correctly pinned.

It's a much simpler problem to solve if you assume someone "certified"
has made the changes. However, that is often not the case (witness the
number of Code violations that you see licensed electricians making
in the name of expedience or economy; how careful do you think folks
will be with network drops?)

Don't know what a relay would do to signal integrity though.
(it probably has to be mechanical due to isolation requirements)

Theo

--- SoupGate-Win32 v1.05
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On 07/06/2025 21:09, Don Y wrote:

On 6/7/2025 9:11 AM, Edward Rawde wrote:

"Don Y" <[email protected]d> wrote in message
news:1020c8h$2oq18$[email protected]...

I need a device that can sit midspan (at a "splice point") and monitor
an ethernet connection for integrity.  At the very least, that
continuity
exists to both ends of the span.

While these are PoE/PoE+ drops, I don't want to place any significant
burden on the PSEs; an external power supply is therefor likely.

In that case I'd just put an unmanaged four port non PoE switch at mid
run and
look into getting access to the LEDs on the switch
which tell me what the link is doing.
The last design I did which had an ethernet port used KS8721BL

But that assumes the cables into and out of the switch are intact
and correctly made.  (see my reply to JW)

Some managed switches (and presumably therefore also managed switch
chips, if you are making it yourself) have support for more detailed
link monitoring and measurement. As well as obvious thinks like
connection rates (a lower than expected rate, or half duplex, indicates
a very suspect electrical connection somewhere) and packet error
counters, some also have measurement of link lengths.

I don't know how this would work with PoE passthrough as well. If you
make the device yourself, of course, it should be relatively
straightforward.

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