1. RFC 6037: Cisco Systems' Solution for Multicast in BGP/MPLS IP VPNs.
Section 3, "Building the Default-MDT": "Each PE router that is a member of a given VRF is configured with a multicast address from the provider's address space. This address, called the 'Default-MDT group address', must be the same for all PE routers that are members of that VRF."
Section 4, "Sending Multicast Packets to Remote PE Routers": "When a PE router receives a multicast packet from a site, it encapsulates the packet... The destination address of the encapsulating... packet is the Default-MDT group address for the VRF."
2. Nokia 7450 ESS, 7750 SR, 7950 XRS, and VSR Services Guide, Release 21.10.R1.
Chapter: Multicast VPN, Section: Rosen MVPN: "The default-MDT uses a specific P-multicast group address to build a P-tunnel to flood C-multicast traffic for a specific MVPN... When C-multicast traffic is received on an ingress PE, the ingress PE encapsulates the C-multicast packets and forwards them over the P-network to the P-multicast group address of the default-MDT."