If the mplsvpn backbone is running over dense mode and serving mvpn services and designers want to migrate the dense mode to ssm. But the mplsvpn core is using type 2 rd which is actually reserve for inter-as mvpn and some of the core routers are running over SB or SRC series ios. During the migration of core; one should not face any type of issue but of mvpwhen migration n customers will start you might face a problem of pim neighborship of vrf not coming up but mdt tunnels up. The main reason for this is that mdt-safi which I have already covered in my previous post. In these cases, ipv4 mdt need to be activated with RR. As soon as it will be configured you will be glad to see mvpn vrf pim neighborships come up.