Re: Mid-span ethernet monitor

On 07/06/2025 21:09, Don Y wrote:

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

"Don Y" <blockedofcourse@foo.invalid> wrote in message news:1020c8h$2oq18$1@dont-email.me...

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.