IP mesh: UDP and AutoInterface

Any IP network carries Reticulum, and the bridge speaks the two interface types the reference implementation uses for a LAN or a mesh: UDPInterface and AutoInterface. That covers a plain Ethernet segment, a Wi-Fi HaLow mesh such as a Haven node, MOROSX or HaLowLink radios running OpenMANET with batman-adv, or anything else that hands the bridge a network device.

AutoInterface

Zero configuration: nodes find each other with IPv6 link-local multicast on the chosen devices and exchange packets over UDP. It is what rnsd, Sideband and CrossTalk do by default, so a bridge on the same segment joins with nothing configured on either side. The bridge follows the reference implementation to the byte: discovery on port 29716 (unicast peering on 29717), data on 42671, the group address and the discovery token derived from the group id, peers expire after 22 s.

Field	Default	Notes
Group id	reticulum	Peers must use the same one
Devices	eth0	Comma separated. wlan0 is refused: on a kit it is the only management path

The device only needs to be up with a link-local address; no IPv4 lease is required.

UDP

One raw Reticulum packet per datagram, broadcast to a forward address and received on a bind address. This is how a Haven or OpenMANET node runs rnsd on the mesh itself:

Field	Haven / OpenMANET value
Listen	0.0.0.0:4242
Forward	10.41.255.255:4242

Or name the device and the bridge derives both from its IPv4 broadcast address.

Configuration

Settings > Routing > Reticulum Interfaces > Add, type AutoInterface or UDP. Environment seeds for a fresh database:

MESHSAT_AUTO_IFACE_DEVICES=eth0
MESHSAT_AUTO_IFACE_GROUP=reticulum
MESHSAT_UDP_LISTEN=0.0.0.0:4242
MESHSAT_UDP_FORWARD=10.41.255.255:4242

On a field kit, plugging the mesh radio's Ethernet into the Pi and adding an AutoInterface on eth0 is the whole job; the Wi-Fi stays untouched.

A peer's side

An rnsd config that talks to the bridge over the same segment needs nothing beyond its own AutoInterface:

[interfaces]
  [[Default Interface]]
    type = AutoInterface
    enabled = yes

Verified

Both types pass announces, packets with proofs and receipts in both directions against a stock rnsd 1.5.4: UDP over loopback, AutoInterface over a virtual Ethernet pair. A real HaLow segment has not been on the bench yet.