High-Speed Serial Interface. For speeds higher than a T1, like SMDS or Frame Relay over T3. It is delivered on a HSSI Processor Card. The HIP card is inserted into any slot on a 7x00 series router and interfaces to the Cisco eXtended bus, or cxbus. The HSSI is also known as the EIA/612/613 standard and it operates at speeds up to 52 Mbps, which enables the interface to be used for SONET (51.82 Mbps), T3 (45), and E3 (34). You can't connect a HSSI with a SCSI cable; it uses a 50-pin Centronics connector and requires a particular cable to connect to the incoming line's DSU. It can then be configured like any serial port.