ES Multicast Not Working, Multicasting enabled and working otherwise

Hello,

Are there any particular steps to debugging zen discovery using multicasting?

I'm able to send multicast traffic between two nodes following these steps:

Here's the output to confirm multicasting is enabled at the router level and functional on the network:

iperf -s -u -B 224.0.55.55 -i 1

Server listening on UDP port 5001
Binding to local address 224.0.55.55
Joining multicast group 224.0.55.55
Receiving 1470 byte datagrams
UDP buffer size: 8.00 MByte (default)

[ 3] local 224.0.55.55 port 5001 connected with 209.41.67.68 port 56666
[ ID] Interval Transfer Bandwidth Jitter Lost/Total Datagrams
[ 3] 0.0- 1.0 sec 128 KBytes 1.05 Mbits/sec 0.010 ms 0/ 89 (0%)
[ 3] 1.0- 2.0 sec 128 KBytes 1.05 Mbits/sec 0.018 ms 0/ 89 (0%)
[ 3] 2.0- 3.0 sec 128 KBytes 1.05 Mbits/sec 0.024 ms 0/ 89 (0%)
[ 3] 0.0- 3.0 sec 386 KBytes 1.05 Mbits/sec 0.023 ms 0/ 269 (0%)

eth0 appears to bind to the 224.2.2.4 IP:
netstat -g
IPv6/IPv4 Group Memberships
Interface RefCnt Group


lo 1 all-systems.mcast.net
eth0 1 224.2.2.4
eth0 1 all-systems.mcast.net
lo 1 ip6-allnodes
lo 1 ff01::1
eth0 1 ff02::1:ff84:7902
eth0 1 ip6-allnodes
eth0 1 ff01::1
eth1 1 ip6-allnodes
eth1 1 ff01::1

Any suggestions on how to debug why nodes are unable to discover eachother using multicast is greatly appreciated.

Thanks!
Ryan

What do the logs say?