A share-multicast distribution tree (MDT) has a share-group address as the group address and is uniquely identified by a share-group address.
Figure 1 shows the share-MDT setup process on a public network that runs PIM-SM.
The PIM P-instance on PE1 sends the rendezvous point (RP) a Join message that carries a share-group address. The RP, that is the P device, receives the Join message and creates the (*, 18.104.22.168) entry. PE2 and PE3 also send Join messages to the RP. A rendezvous point tree (RPT) is thus created in the multicast domain (MD), with the RP at the root and PE1, PE2, and PE3 at the leaves.
The PIM P-instance on PE1 sends the RP a Register message that has the multicast tunnel interface (MTI) address as the source address and the share-group address as the group address. The RP receives the Register message and creates the (10.1.1.1, 22.214.171.124) entry. PE2 and PE3 also send Register messages to the RP. Then, three independent RP-source trees that connect PEs to the RP are built in the MD.
On the PIM-SM network, an RPT (*, 126.96.36.199) and three independent RP-source trees construct a share-MDT.