Since its release, InfiniBand has been made in 5 speeds and has used two types of connectors.
FDR InfiniBand provides a 56 Gbps second link. The data encoding for FDR is different from the other InfiniBand speeds: for every 66 bits transmitted 64 bit are data. This is cable 64b/66b encoding. This provides actual speeds of 54 Gbps.
FDR uses the QSFP connector but the cable must be built for FDR use. This will be noted on the cable.
FDR can be used as 10 Gbps or 40 Gbps Ethernet.
Like FDR, the physical connection of FDR-10 is 56 Gbps. FDR-10 uses the same data encoding as older, slower InfiniBand speeds: for every 10 bits transmitted, 8 bits are data. This is called 8b/10b encoding. This reduces the actual speed of transfer 40 Gbps.
FDR-10 does require the FDR specific cable but maintains the use of the QSFP connector.
FDR-10 can be used as 10 Gbps or 40 Gbps Ethernet
QDR InfiniBand provides a 40 Gbps link. 8b/10b encoding is used by QDR which provides actual speeds of 32 Gbps.
The QSFP connector is used by QDR InfiniBand.
QDR InfiniBand may be used as 10 Gbps or 40 Gbps Ethernet.
DDR InfiniBand provides a 20 Gbps link. 8b/10b encoding is used which provides actual speeds of 16 Gbps.
DDR InfiniBand may use either CX4 or QSFP connectors.
SDR InfiniBand provides a 10 Gbps link. 8b/10b encoding is used which provides actual speeds of 8 Gbps.
SDR InfiniBand uses the CX4 connector.