Hello
Today I was playing with multicast over a GRE tunnel and I had this weird problem where I could ping from a source all the way to an IGMP receiver over the GRE tunnel, but if I pinged back, that is I joined the multicast group on the interface near a source, I couldn’t ping it from the other end.
After 30 minutes of tshooting I simply wrote the config on all routers, reloaded, and was then able to ping everything back and forth. Weird, but i’ve seen this in production a few times, so i guess that something got stuck.
