HP MSR2003 Configuration Manual page 185

Uses the address to encapsulate the multicast packets for that VPN.
• All the PE devices in the network monitor the forwarding rate on the default-MDT.
a. When the rate of a VPN multicast stream that entered the public network at a specific PE device
exceeds the threshold, the PE device initiates an MDT switchover message. The message
travels to the downstream along the default-MDT. This causes a data-MDT to be built by using
the data-group between that PE device and the remote PE devices with downstream receivers.
b. After a data-delay period has passed, an MDT switchover process starts. All VPN multicast
packets that have entered the public network through that PE device are not encapsulated with
the default-group address. They are encapsulated into public network multicast packets with
the data-group address. Then they are switched from the default-MDT to the data-MDT.
For more information about MDT switchover, see
NOTE:
A VPN uniquely corresponds to an MD and an MD provides services for only one VPN, which is called a
one-to-one relationship. Such a relationship exists between VPN, MD, MTI, default-group, and the
data-group address range.
PIM neighboring relationships in MD-VPN
Figure 59 PIM neighboring relationships in MD-VPN
PIM neighboring relationships are established between two or more directly interconnected devices on
the same subnet. As shown in
MD-VPN:
PE-P PIM neighboring relationship—Established between the public network interface on a PE
•
device and the peer interface on the P device over the link.
PE-PE PIM neighboring relationship—Established between PE devices that are in the same VPN
•
instance after they receive the PIM hello packets.
• PE-CE PIM neighboring relationship—Established between a PE interface that is bound with the
VPN instance and the peer interface on the CE device over the link.
Figure 59, the following types of PIM neighboring relationships exist in
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"MDT switchover."