To implement multicast VPN, the following network conditions need to be met:
l Each site supports multicast based on VPN instances.
l Public network supports multicast based on the public network instance.
l PE device supports multi-instance multicast:
– Connecting sites through a VPN instance, and supporting multicast based on the VPN
instance
– Connecting the public network through the public instance, and supporting multicast
based on the public network instance
– Supporting information communication and data switching between the public network
instance and the VPN instance
8.2 IPv4 Multicast VPN Supported by the S7700
The system supports multiple IPv4 multicast VPN features, including MD VPNs, share-MDT
and switch-MDT switchover, and inter-AS MD VPNs.
MD VPN
The S7700 applies Multicast Domain (MD) to implement multicast VPN, which is called MD
VPN. In an MD, VPN data is transmitted through the Multicast Tunnel (MT).
The greatest advantage of the MD solution is that only PEs are required to support multi-instance.
MD neither needs to upgrade CEs and Ps, nor modify the previous Protocol Independent
Multicast (PIM) configuration on CEs and Ps. That is, the MD solution is transparent to CEs
and Ps.
Users can bind Share-Group to Multicast Tunnel Interfaces (MTIs), and set MTI parameters.
Share-Multicast Distribution Tree
For a VPN instance, data transmission in the public network is transparent. The VPN data is
seamlessly connected at MTIs on PEs: The VPN instance only knows that after it sends the VPN
data through an MTI on local PE, and the remote PE can receive the data through an MTI.
Actually, the data experiences the complex public network transmission process, that is,
multicast distribution tree (MDT) transmission.
The MDT that takes the address of Share-group as the group address is called Share-MDT. VPNs
use Share-Group to uniquely identify a Share-MDT.
Multicast can be enabled in a PIM-SM network or a PIM-DM network. In the two different
modes, the process of setting up a Share-MDT is different.
Switch-MDT Switchover
When multicast data is forwarded through a Share-MDT in the public network, the multicast
data is forwarded to all PEs that support the same VPN instance, regardless of whether there is
a receiver in the site connected to PEs. When the rate of VPN multicast data is higher, it may
lead to data flooding, which wastes the network bandwidth and adds load to PEs.
The S7700 optimizes the MD. Special Switch-MDTs is set up between PEs connected to VPN
receivers and PEs connected to the VPN multicast source for VPN multicast data of a high rate
Quidway S7700 Smart Routing Switch
Configuration Guide - Multicast 8 IPv4 Multicast VPN Configuration
Issue 01 (2011-07-15) Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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