Method to do pubsub over local network only

Hello, I was talking to folks at the IPFS Thing last week about how I have a use case where I'd like to keep gossip to a particular network interface or to limit it to a local network.

The general use case is for local network service discovery / gossip which lets you find folks advertising data on your wifi hotspot/router rather than globally gossiping about a topic. For this use case the application would have a hardcoded "service discovery" topic so that peers wouldn't need an extra layer of data exchange to establish gossip.

I was wondering if this is something that could be done with the existing libp2p pubsub implementations or if it's something we could spec out as a standard.

I have some thoughts on how it could be done, but I wanted to do a temperature check on whether it's something we could spec out before writing too much about it.

Start by reviewing the existing libp2p pubsub implementations and specifications, then examine whether interface or local-network limits can support service discovery on a hardcoded topic. Done would require an agreed scope and a specification or decision on whether this should become a standard; the issue names no files or tests.