MDT-based MVPN inter-AS option A
As shown in Figure 74:
Two VPN instances are in AS 1 and AS 2.
PE 3 and PE 4 are ASBRs for AS 1 and AS 2, respectively.
PE 3 and PE 4 are interconnected through their respective VPN instance and treat each other as a CE.
Figure 74: MVPN inter-AS option A
To implement MVPN inter-AS option A, a separate MVPN must be created in each AS. Multicast data is transmitted between the VPNs in different ASs through the MDs.
Multicast packets of VPN instance 1 are delivered as follows:
CE 1 forwards the multicast packet of VPN instance 1 to PE 1.
PE 1 encapsulates the multicast packet into a public network packet and forwards it to PE 3 through the MTI interface in MVPN 1.
PE 3 considers PE 4 as a CE of VPN instance 1, so PE 3 forwards the multicast packet to PE 4.
PE 4 considers PE 3 as a CE of VPN instance 2, so it forwards the multicast packet to PE 2 through the MTI interface in MVPN 2 on the public network.
PE 2 forwards the multicast packet to CE 2.
Because only VPN multicast data is forwarded between ASBRs, different PIM modes can run within different ASs. However, the same PIM mode must run on all interfaces that belong to the same VPN (including interfaces with VPN bindings on ASBRs).