H3C Technologies H3C S12500 Series Switches - Manual (Page 261)

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Share-MDT establishment in a BIDIR-PIM network
Figure 70 Share-MDT establishment in a BIDIR-PIM network
As shown in Figure 70 , BIDIR-PIM is enabled in the network and all the PE devices support VPN instance
A. The process of establishing a share-MDT is as follows:
1. The public network on PE 1 initiates a join to the public network RP, with the share-group address
as the multicast group address in the join message, and a (*, 239.1.1.1) entry is created on each
device along the path on the public network. At the same time, PE 2 and PE 3 respectively initiate
a similar join process. Finally, the receiver-side RPT is established in the MD, with the public
network RP as the root and PE 1, PE 2 and PE 3 as leaves.
2. The public network on PE 1 sends multicast data, with the share-group address as the destination
multicast group address. The DF on each subnet that the multicast data travels through on the
public network unconditionally forwards the data to the RP, and a (*, 239.1.1.1) entry is created
on each device along the path. At the same time, PE 2 and PE 3 respectively initiate a similar
process. Finally, the source-side RPT is established in the MD, with PE 1, PE 2, and PE 3 as the roots
and the public network RP as the leave.
In the BIDIR-PIM network, the receiver-side RPT and the source-side RPT constitute a bi-directional RPT (the
(*, 239.1.1.1) tree), which is a share-MDT.