InfiniBand speeds

InfiniBand names each generation with a short code. The code is a per-lane rate; the port bandwidth is that rate times the link width (usually ×4).

Generations (per lane)

Generation	Per lane	×4 port
SDR	2.5 Gb/s	10 Gb/s
DDR	5 Gb/s	20 Gb/s
QDR	10 Gb/s	40 Gb/s
FDR	~14 Gb/s	~56 Gb/s
EDR	25 Gb/s	100 Gb/s
HDR	50 Gb/s	200 Gb/s
NDR	100 Gb/s	400 Gb/s

Modules

Because the common port is ×4, InfiniBand rides QSFP-family optics: EDR on QSFP28, HDR on QSFP56, and NDR on OSFP or QSFP112. The form factor follows the per-lane rate and lane count, just as it does for Ethernet.

Early generations (SDR–QDR) used 8b/10b line coding; FDR and later moved to 64b/66b, which is why FDR's per-lane figure is about 14 rather than 12.