I have a series of components that communicate over localhost on Windows. For various reasons that I won't get into (combination of company VPN blocking us, and need to re-use same port across components), these components use an IP address scheme as follows:
127.x.x.x
For instance, one component may be assigned 127.1.2.3, another 127.2.4.6.
I have a case where a message from component A needs to go to component B and C, but not D.
I can't use multicast - we have a VPN that blocks multicast over localhost, or at least, I was unsuccessful in using multicast unless I turned off the VPN (but this is not a viable path, we need to have the VPN on going forward).
So next I thought to try broadcast. Broadcast, however, would not work because I only want some of the components to receive it based on the second octet.
For example, message A should only go to components assigned to 127.1.x.x, and message B should only go to components assigned to 127.2.x.x.
First I tested broadcast with 127.255.255.255 and verified all components were able to receive that message.
Then I tried to isolate to that specific subnet: 127.1.255.255.
Unfortunately, when I do this, I get a "destination unreachable" error in Wireshark.
So to summarize my question, broadcast over localhost works if I use 127.255.255.255, but is it possible to target specific subnets (eg, 127.1.255.255)?