This is the first-generation GSM Digital Unit for RBS 6xxx. It combines the baseband processing and back-haul interface of up to 12 TRX, in 1..6 logical BTSs.
The DUG 10 has 6 HSIO connectors for the interface towards the RUG units. The cable between DUG 10 and RUG is called "RPM 777 301/00900"
The back-haul interface is Classic T1/E1 (ISDN) based. The DUG 10 has four T1/E1 ports exposed as RJ45 connectors.