All - I'd like to thank Mladen for his contribution of a multicast trace program to FRR. This is a implementation of draft https://tools.ietf.org/html/draft-ietf-idmr-traceroute-ipm-05 . The command can be run from inside of vtysh with `mtrace <source>`. Alternatively it can be invoked from the command line as `mtracebis <source>`. thanks! donald