Stands for multicast backbone, an experimental portion of the Internet that is used to test multicasting technology.
The MBone platform was established in 1992 to test and develop technology and software for multicasting audio and video information over the Internet. It consists of a portion of the Internet with specially configured routers that support routing of multicast Internet Protocol (IP) packets.
These MBone routers can forward IP packets through nonmulticast routers using tunneling technologies that encapsulate multicast IP packets into unicast packets that the routers can understand.
MBone IP addresses used for multicasting of audio and video information have been allocated by the Internet Assigned Numbers Authority (IANA) as those in the range 224.2.y.z, which is a subset of the class D group of IP addresses ranging from 224.0.0.0 to 239.255.255.255.