Bridging multicast address between LAN and WAN


I'm currently working on the following scenario:-

Two routers, R1 and R2. Both running different versions of Openwrt.
R1 is a wired router between the internal network and the Internet.
R2 is a wireless router connected to a LAN switch port on R1.
R1 and R2 both provide DHCP services to their respective LANs for different subnets.

A DLNA DMR (renderer) is connected to another LAN switch port on R1.
A DLNA DMS (server) is connected to a LAN switch port on R2.
Both of these devices use the multicast address UDP port 1900 (SSDP) to discover other devices.

Available interfaces on R2 are eth0.2 (WAN) and br-lan (LAN, including wireless clients).
I would like to repeat these multicast packets received from eth0.2 to br-lan and vice-versa.
I have installed smcroute and tcpdump onto R2.
So far, I have managed to get R2 to join on the WAN and repeat packets to br-lan, which I have observed using tcpdump.
The opposite direction (R2 LAN -> R2 WAN (R1 LAN)) however doesn't seem to work.

Admittedly I've never used smcroute before and I'm not certain if I am configuring it correctly.
Does anyone have experience setting this up? :slight_smile:

I know that SSDP packets from R2 will contain a LAN address for the server, but I can fudge that by adding a static route on R1 for that address to go via R2.

This is my current smcroute.conf:-

phyint eth0.2 enable ttl-threshold 11                           
phyint br-lan enable ttl-threshold 3

mgroup from eth0.2 group
mroute from br-lan group to eth0.2