MDT-based MVPN inter-AS option C
As shown in Figure 76:
A VPN network involves AS 1 and AS 2.
PE 3 and PE 4 are the ASBRs for AS 1 and AS 2, respectively.
PE 3 and PE 4 are interconnected through MP-EBGP and treat each other as a P device.
PEs in different ASs establish a multihop MP-EBGP session to advertise VPN-IPv4 routes to each other.
Figure 76: MVPN inter-AS option C
To implement MVPN inter-AS option C, only one MVPN needs to be created for the two ASs. Multicast data is transmitted between the two ASs through the MVPN.
Multicast packets are delivered as follows:
CE 1 forwards the VPN instance multicast packet to PE 1.
PE 1 encapsulates the multicast packet into a public network multicast packet and forwards it to PE 3 through the MTI interface on the public network.
PE 3 and PE 4 are interconnected through MP-EBGP, so PE 3 forwards the public network multicast packet to PE 4 along the VPN IPv4 route.
The public network multicast packet arrives at the MTI interface of PE 2 in AS 2. PE 2 decapsulates the public network multicast packet and forwards the VPN multicast packet to CE 2.