this we can achieve from ip pim auto-rp mapping-agent command but I have not tried ..Dont have image. With L2IRON man this command is not supporting.

ip pim auto-rp mapping-agent
To configure the router as an IPv4 Protocol Independent Multicast (PIM) Auto-RP mapping agent that sends RP-Discovery messages, use the ip pim auto-rp mapping-agent command. To remove the mapping agent configuration, use the no form of this command.

https://www.cisco.com/c/m/en_us/tech...ing-agent.html