Accessing Devices on Different Subnets Using a Switch

layer2layer3subnetswitchswitching

I have two devices which come up with default IP addresses:

  • Device 1 – 192.168.168.168 mask 255.255.255.0
  • Device 2 – 192.168.1.254 mask 255.255.255.0

I can commonly deduce that both the devices are part of the 192.168.0.0/16 network. Is that a correct assumption?

The reason I ask is because I want to manage both the devices at the same time, and I will be connecting both of these devices to a dumb ethernet switch (no VLANs etc. – really dumb). I plan to also connect a PC to the switch.

I am thinking of using 192.168.2.5/16 as the IP address of the PC. Let me know if I will be able to access the device, or is this not a good practice.

Edit:

I cannot change the default IP addresses the devices have when they come up. When the devices go to a bad state, and I factory default them, these are the IP addresses they come up with.

So when the packet from the PC with
src-ip : 192.168.2.5/16 & dst-ip : 192.168.168.168

comes to device 1 (assuming that the dumb switch just sent it on all ports), why will device-1 not respond?

Best Answer

Now I can commonly deduce that both the devices are part of the 192.168.0.0/16 network. Is that a correct assumption.

No, that's incorrect. You're using netmask 255.255.255.0, so that are two different /24s. Just because you can summarize them to a /16 doesn't make it a /16.

If you want this to work, you'll need to change the netmask on all devices to /16, or place a router which is connected to both /24s and routes packets between them.

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