Protocols And Standards; How Md-Vpn Works; Share-Mdt Establishment - HP MSR ASM Configuration Manual

PE-PE neighboring relationship—PIM neighboring relationship established after a VPN instance on
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a PE device receives a PIM hello from a VPN instance on a remote PE device through an MTI.
PE-CE neighboring relationship—PIM neighboring relationship established between a
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VPN-instance-associated interface on a PE device and an interface on a peer CE device.

Protocols and standards

draft-rosen-vpn-mcast-08, Multicast in MPLS/BGP IP VPNs

How MD-VPN works

This section describes how the MD-VPN technology is implemented, including the construction of a
share-MDT, delivery of multicast traffic based on the share-MDT, and implementation of multi-AS
MD-VPN.
For a VPN instance, multicast data transmission on the public network is transparent. The MTIs at the
local PE device and the remote PE device form a channel for the seamless transmission of VPN data over
the public network. All that is known to the VPN instance is that the VPN data is sent out of the MTI and
then the remote site can receive the data through the MTI. Actually, the multicast data transmission
process (the MDT transmission process) over the public network is very complicated.

Share-MDT establishment

The multicast routing protocol running on the public network can be PIM-DM, PIM-SM, BIDIR-PIM, or
PIM-SSM. The process of creating a share-MDT is different in these PIM modes.
Share-MDT establishment in a PIM-DM network
Figure 63 Share-MDT establishment in a PIM-DM network
PE 1
BGP: 11.1.1.1/24
As shown in
A. The process of establishing a share-MDT is as follows:
1. The public network on PE 1 initiates a flood-prune process in the entire public network, with the
BGP interface address (namely the interface address used to establish the BGP peer) as the
multicast source address and the share-group address as the multicast group address.
BGP: 11.1.3.1/24
PE 3
P
MD
Figure 63, PIM-DM is enabled in the network and all the PE devices support VPN instance
Share-Group: 239.1.1.1
Public network BGP peers
SPT (11.1.1.1, 239.1.1.1)
SPT (11.1.2.1, 239.1.1.1)
SPT (11.1.3.1, 239.1.1.1)
PE 2
BGP: 11.1.2.1/24
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