On comparing log information before and after, it was found NE40E fails to establish BGP peer relationships with 16 ALU 7750 devices. When examine the event, we enable the bgp debugging. The following information was shown from the debug:
RM/6/RMDEBUG:(Public):Receive unsupported orf type from peer (10.100.90.1). orf type(3), orf mode(Both)
It was apparently BGP protocol mismatch happened causing the connection to fail to setup.