Discovery/Signaling via UDP Multicast

I have an application that should allow sharing of data even if there is
no Internet access at all (think sharing data in disaster conditions, or
with repressive censorship), but the nodes are in a LAN (at least some
of the time). At the moment, it seems like the practical signalling
channels are:

· a STUN server reachable by both endpoints, with a permanent & public name
· a web server reachable by both endpoints, with a permanent & public name
· User interaction, say entering the signalling information in a text
box, or via QR code, or via sound->microphone

Is there any reason why there is no additional channel for
discovery/signalling via a simple UDP multicast protocol, whether custom
or zeroconf/mDNS?
This seems fairly straightforward to implement. Apart from my use case,
it would speed up connection setup between hosts in the same LAN.

Are there security considerations in play? I don't think of my use case
as esoteric at all, but there must be a reason why I cannot find any
discussion or implementation of UDP multicast discovery/signalling. If
my weak google-fu is to blame, I would appreciate a pointer.

- Philipp

Received on Sunday, 4 October 2015 16:42:14 UTC