Hello all,

Is it possible to make ARP proxy work for only one subnet ?

I have a Mikrotik RB1100AHx2 plugged on a switch with multiple subnets but Mikrotik only knows how to route one subnet (say 192.0.2.0/24). Unfortunately Mikrotik often answer ARP requests for a computer on another subnet on the lan (198.51.100.0/24) and of course connection breaks
Here is a small diagram :
With ARP proxy enable :
* Computers in group 1 can join computers in its own group and computers in group 3
* Computers group 3 can join computers on its own group and computers in group 1

But sometime computers in group 2 can't connect to computers in group 2 because RB1100 answer faster to arp request.
I'd like ARP proxy to be active only to request to/from 192.0.2.0/24 not 198.51.100.0/24

Is there a way to do that ?
Denis

If you give the RouterBoard an IP address on 198.51.100.0/24 on the relevant interface then proxy arp will not reply to requests from that subnet.

If those switches support VLANs I would suggest moving to VLANs and dumping proxy arp.

If you give the RouterBoard an IP address on 198.51.100.0/24 on the relevant interface then proxy arp will not reply to requests from that subnet.

Thank you very much for that answer !
I hadn't try that because I had 192.0.2.1/24 on an interface and arp-proxying is working on that subnet. But adding an IP on 198.51.100.0/24 made it work as expected

Glad to hear that it solved the immediate problem. Don't forget to consider migrating to a VLAN solution at some point.