[kea-dev] More Kea/OpenWRT integration

[Morten Brørup]

> From: Philip Prindeville [mailto:philipp_subx at redfish-solutions.com]
> Sent: Thursday, 29 January 2026 21.34
> 
> > On Jan 29, 2026, at 12:58 PM, Morten Brørup
> <mb at smartsharesystems.com> wrote:
> >
> >> On OpenWRT we support a host having multiple MAC addresses for the
> same
> >> IP, to allow people to have laptops with docking stations and WiFi
> and
> >> to roam without losing connectivity.
> >
> > I'm sorry if my question is off-topic, but this scenario got me
> really curious!
> >
> > Can you please elaborate about how having the same IP address on
> Ethernet and Wi-Fi works on the laptop?
> >
> > Are both interfaces on the laptop active at the same time?
> > How does the laptop respond to ARP?
> > Is it controlled by the "metric" on the laptop's route table, or does
> it respond to ARP depending on the interface where the ARP request was
> received, or something else?
> >
> > Which laptop operating systems does it work with? Windows? Mac?
> Linux?
> >
> > -Morten
> >
> 
> 
> I can't tell you how all systems will behave, but I do know that the
> Linux IP neighbor table caches the interface associated with an ARP
> query (as well as the interface, IP and MAC of the requestor as an
> optimization).
> 
> It's not ARP that's driving this, though, it's DHCP.  Whenever carrier
> on an interface flaps and that interface is configured to use DHCP, a
> DHCP request will be sent on that interface, or the DHCP settings on
> that interface will be scrubbed (for up and down transitions,
> respectively).
> 
> Typically Ethernet has a better metric than WiFi, so even if both are
> up your docking station will be preferred if it has carrier (i.e. is
> connected).

Makes sense; thanks for the explanation. :-)