What is MSDP Multicast Source Discovery Protocol?

MSDP gives inter-domain admittance to multicast sources in all domains by empowering all rendezvous points (RPs) to find multicast sources outside of their domains. RPs additionally use MSDP to announce sources that are transmitted to a multicast group. This convention makes it conceivable to utilize independent multicast routing within the domains, while the multicast sessions beginning from or to different domains reach all the members.