HP FlexNetwork 7500 Series Configuration Manual page 196

Default-MDT establishment in a PIM-SM network
Figure 65 Default-MDT establishment in a PIM-SM network
As shown in
instance A. The process of establishing a default-MDT is as follows:
PE 1 initiates a join to the public network RP by specifying the multicast group address as the
1.
default-group address in the join message. A (*, 239.1.1.1) state entry is created on each
device along the path on the public network.
At the same time, PE 2 and PE 3 separately initiate a similar join process.
2.
Finally, an RPT is established in the MD, with the public network RP as the root and PE 1, PE 2,
and PE 3 as leaves.
To establish PIM neighboring relationships with PE 2 and PE 3 through the MTI in VPN
3.
instance A, PE 1 performs the following actions:
a. Encapsulates the PIM protocol packet of the private network into a public network multicast
data packet. PE 1 does this by specifying the source address as the IP address of the MD
source interface and the multicast group address as the default-group address.
b. Sends the multicast data packet to the public network.
This action triggers the registration of the multicast source with the public network RP. Then,
the public network RP initiates a join to PE 1. An (11.1.1.1, 239.1.1.1) state entry is created
on each device along the path on the public network.
At the same time, PE 2 and PE 3 separately initiate a similar register process.
4.
Finally, three SPTs between the PE devices and the RP are established in the MD.
In the PIM-SM network, the RPT, or the (*, 239.1.1.1) tree, and the three independent SPTs
constitute a default-MDT.
Figure 65, PIM-SM is enabled on the network, and all the PE devices support VPN
186