in your customer case it sounds like the wan and lan of their router are also in the same lanbypass group which joins their internal switch to their wan Kindest regards, Tom Smyth. On Wed, 16 Sept 2026, 22:16 Tom Smyth, <tom.smyth@wirelessconnect.eu> wrote:
hi Brandon... it sounds like alan-bypass is enabled ( usually by jumpers or a dip switch on the router
it is an 8 pole relay between two nic interfaces for passing through traffic in the event of a failure of a router... ( config for appropiate use of bypass is p1 uplink connected to a primary router with a lanbypass as a group or( when the device is booted up acts as a layer 2 bridge ) then the backup router is plugged into the second port of tje lanbypass group
so the router acts like a layer 1 passthrough cable to the 2nd router when it is switched off or being reset ( and in normal operation a layer2 device exposing the bridged wan of the primary router and the wan of 2ndary router to the 1 port of yhe upstream ntu...
( idea is that 1 port can be passed through 2
Kindest regards, Tom Smyth.
On Wed, 16 Sept 2026, 22:03 Brandon Martin via NANOG, < nanog@lists.nanog.org> wrote:
I have a customer who's Eero seems to be exposing either their entire LAN L2 or at least several Eero MACs to the SP side consistently upon every reboot, and given the lack of configurability that the Eero presents, I'm at a loss to figure out how to make it not do that.
Some sources suggest this is "expected behavior" which seems baffling. I can't imagine many SPs take kindly to having their access network flooded with dozens of MACs all asking for addressing via DHCP on a single access port.
Is this really "expected behavior" from a customer edge router, these days? If so, what's the protocol people have adopted to handle it? The only thing I can think of is very short MAC aging at L2 and then blindly handing any device that shows up on the same access port the same addresses regardless of what L2 address it purports to have.
Of course that doesn't fix the fact that any device on the customer's network that successfully completed the DHCP exchange while the true border Eero was "getting ready" now has unusable addressing. Turning DHCP lease times down low enough to combat this without the customer noticing is pretty much a non-starter.
So what gives?
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