BBU3806 - Inter-BBU interface

Hello all.

Regarding DBS3806 system, two basebands BBU3806 can work as Master-Slave connecting both BBU with a MDR36 cable between EIa port of each baseband. Does anybody know if the cable MDR36 needed to this connections is a special one?. I have tried to connect them with a direct cable, an old SCSI cable but the slave BBU is not recognized by the master BBU.

If someone knows the type of cable needed or its P/N I will be very grateful if you let me know.

Thanks a lot.