Hello everyone,
my first post here. My networking skills are hmm okay, but this kind of edge case is reaching my limits. Played with Mikrotik in uni, some 8 years ago... I have a funky scenario, I'm not asking for a solution, but more of an answer to a) is my idea absolutely stupid, b) can CCR2004 or CSS326 be used?

Situation:
- I have 6 or 8 or 16 (plenty, numbers varies on number of ports on a router/switch) devices with the *same IP address* (thanks god, they have different MACs), I cannot change IP, data volume is small,
- I have a computer (Linux) which wants to talk to all of them over Ethernet.

My imagined solution:
- grab a router/smart-switch,
- connect devices to separate ports,
- setup each port to a different VLAN, except for one port (used for the computer),
- therefore same IP is not a problem - different VLANs,
- the computer on another port, but since the other devices are on different VLANs, it cannot communicate with them yet,
- so setup some firewall/routing per VLAN - get source IP i.e. 10.10.10.1 + VLAN tag 2, and route them as different IP to my computer, i.e. 10.10.10.1(tag2) becomes 192.168.123.2, 10.10.10.1(t3) becomes 192.168.123.3
- put the computer on. 192.168.123.0/24 network, since now the devices have different IP, they can be easily accessed.

This is such a funky weird case Does this idea make any sense? And can it be done on i.e. CCR2004 or CSS326?

Thanks!

I think it should be possible with VRF: https://www.youtube.com/watch?v=-hdLsXd9OgE. The video is not exactly what you want (the devices with the same IP address try to go to the internet in that video), but you should get the idea of interacting with multiple devices sharing the same IP address from there. I don't think VLAN is even needed. You can just keep the individual etherX ports out of the main bridge.

You need one L3 interface per device with same IP address. It can either be a router with multiple routed ports or a VLAN-enabled switch with each pirt set as access port to different VLAN and backed with router using many VLANs.

There were a few discussions about the same issue before (solutions were fit for slightly older ROS versiobs, but should conceptually work with v7 as well):

viewtopic.php?t=187178
viewtopic.php?t=130127

Thank you everyone, so seems doable. CCR2004 Ordered I’ll hack it up sometime next week. If I have time I might update the post with actual solution I did.