(Multicast backBONE) A group of servers throughout the Internet that support the IP multicast protocol (one-to-many) and allow for live audio and video transmission. When it is necessary to leave the Mbone and traverse a part of the Internet that does not support multicast packets, the packets are tunneled into normal packets. Mbone routers (mrouters) encapsulate the multicast packets into unicast packets and unencapsulate them on the receiving side.