Hi Hayashi,
I am not sure what you mean by link, but generally in SRM the backend vendors are mapped to the supplier business partners in table VENMAP. This is the same in a SUS/ROS client too. After the ROS supplier has been transfered to ECC and replicated back to SUS/ROS there should be one entry in this table with the backend vendor number and the business partner GUID. You can use view BBPV_BUPA_VENMAP to easily identify the BP number for the vendor number.
regards
Zoltan