Share-Mdt-Based Delivery - HP A6600 Configuration Manual

Share-MDT establishment in a PIM-SSM network
Figure 68 Share-MDT establishment in a PIM-SSM network
PE 1
BGP: 11.1.1.1/24
As shown in Figure
The process of establishing a share-MDT is as follows:
The public network on PE 1 sends the local BGP MDT routing information, including its BGP interface
address and the share-group address, to PE 2 and PE 3. PE 2 and PE 3 perform the same operation to
exchange their BGP MDT routing information with one another. After receiving the BGP MDT information
from PE1, PE 2 and PE 3 respectively send a subscribe message for channel subscription hop by hop
toward the BGP interface of PE1. A (11.1.1.1, 232.1.1.1) entry is created on devices on the path toward
PE 1 in the public network. Thus an SPT is created in the network, with PE 1 as its root, PE 2 and PE 3 as
its leaves.
At the same time, PE 2 and PE 3 respectively initiate a similar SPT establishment process. Finally, three
independent SPTs are established in the MD. In the PIM-SS M network, the three independent SPTs
constitute a share-MDT.
In PIM-SSM, subscribe messages are used equivalent to join messages.
Characteristics of a share-MDT
A share-MDT is characterized as follows, no matter what PIM mode is running in the public network:
All PE devices that support this VPN instance join the share-MDT.
•
All VPN multicast packets that belong to this VPN, including protocol packets and data packets, are
•
forwarded along the share-MDT to every PE device in the public network, even if they have no active
receivers downstream.

Share-MDT-based delivery

A share-MDT can be used for delivering multicast packets, including both multicast protocol packets and
multicast data packets. However, the transmission processes for these two types of multicast packets are
different.
Delivering multicast protocol packets
To forward the multicast protocol packets of a VPN over the public network, the local PE device
encapsulates them into public-network multicast data packets. These packets are transmitted along the
BGP: 11.1.3.1/24
PE 3
P
MD
BGP: 11.1.2.1/24
68, PIM-SSM is enabled in the network and all the PE devices support VPN instance A.
Share-Group: 232.1.1.1
Public instance BGP peers
SPT (11.1.1.1, 232.1.1.1)
SPT (11.1.2.1, 232.1.1.1)
SPT (11.1.3.1, 232.1.1.1)
PE 2
223