MDTs are multicast tunnels through the P-network. MDTs transport customer multicast traffic encapsulated in GREs that are part of the same multicast domain. The two types of MDTs are as follows:
The Default-MDT— An mVRF uses this MDT to send low-bandwidth multicast traffic or traffic that is destined to a widely distributed set of receivers. The Default-MDT is always used to send multicast control traffic between PE routers in a multicast domain.
The Data-MDT— This MDT type is used to tunnel high-bandwidth source traffic through the P-network to interested PE routers. Data-MDTs avoid unnecessary flooding of customer multicast traffic to all PE routers in a multicast domain.
When a VRF is multicast enabled (as described in