[rescue] What is this traffic?

[Mouse]

> My network is an ADSL router into an 8 port TP-Link unmanaged switch.
> For a long time now, when my network is idle (as far as I know) the
> switch has been showing a very high level activity on the line from
> the router while the router itself shows no activity on the WAN/LAN.

Curious, at the very least.

Personally, I would take a machine with two Ethernets, bridge them in
software (from memory, for the NetBSD version I'd use: ifconfig bridge0
create; brconfig bridge0 add INTF1; brconfig bridge0 add INTF2;
ifconfig bridge0 up; brconfig bridge0 up), interpose that between the
two devices, and fire up tcpdump.

Depending on what the issue is, the problem might go away entirely (eg,
some autonegotiation issues will disappear under such a setup).  It
also might persist, in which case you might be able to see what's up.

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