Topology: In the topology there is router NE20-1 (VRP5.10-1243.01) and router NE20-2 (VRP5.10 Release 1243.01). They serve as P device. NE20-1 and NE20-2 are connected through eight 2M binding. NE20-1 connects core NE40 (It is PE.) through POS and under NE20 there is AR28-11. It connects NE20 (NE20-1 and NE20-2) through 2M and AR28-11 acts as PE device and NE40 also serves as PE.
NE20-2 router enable MPLS LDP at connected interface (8*2M binding) and it cannot ping through loopback interface address of NE40-8.
Shutdown all 2M of NE20-1 and NE20-2 and then undo shutdown. VT renegotiates and the problem is solved.
For 2M binding, VT negotiation is problematic.