HP MSR2003 Configuration Manual page 184

As shown in Figure
that provides services for a particular VPN instance. All the VPN multicast traffic in that VPN is
transmitted within that MD.
• Inside an MD, all the private traffic is transmitted through the MT. The process of multicast traffic
transmission through an MT is as follows:
a. The local PE device encapsulates a VPN multicast packet into a public network multicast
packet.
b. The encapsulated multicast packet is sent by the PE device and travels over the public network.
c. After receiving the multicast packet, the remote PE device decapsulates the multicast packet to
get the original VPN multicast packet.
The local PE device sends VPN data out of the MTI. The remote PE devices receive the private data
•
from their MTI interfaces.
As shown in Figure
an entrance or exit of the pool. The local PE device puts the private data into the transmission pool
(MD) through the entrance (MTI). The transmission pool automatically duplicates the private data
and transmits the data to each exit (MTI) of the transmission pool. Each remote PE device that
needs the data can get the private data from its exit (MTI).
Figure 58 Relationship between PIM on the public network and an MD in a VPN instance
Each VPN instance is assigned a unique default-group address. The VPN data is transparent to the
•
public network.
A PE device encapsulates a VPN multicast packet (a multicast protocol packet or a multicast data
packet) into a public network multicast packet. The default-group address is used as the public
network multicast group. Then, the PE sends this multicast packet to the public network.
• A default-group corresponds to a unique MD. For each default-group, a unique default-MDT is
constructed through the public network resources for multicast data forwarding. All the VPN
multicast packets transmitted in this VPN are forwarded along this default-MDT, regardless of which
PE device they used to enter the public network.
An MD is assigned a unique data-group address range for MDT switchover. When the rate of a
•
VPN multicast stream that entered the public network at a PE device reaches or exceeds the
switchover threshold, the PE does the following:
Selects an address that is least referenced from the data-group address range.
57, the ellipse area in the center of each VPN instance plane represents an MD
58, you can think of an MD as a private data transmission pool and an MTI as
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