[Moissanite]

EFA is not InfiniBand. It has similar goals (low latency via kernel bypass), but is implemented using AWS Nitro NICs and regular Ethernet networking.

Other providers (Azure and Oracle) do offer InfiniBand, but that creates a problem with "islands" of compute which can't be easily expanded. There are also more security considerations when using IB in a multi-tenant environment which makes it not such a slam-dunk advantage as you might first assume.

[carlsborg]

You're right, EFA is custom nitro NICs. Although Mellanox (now Nvidia ConnectX) is not solely Inifiband either - Nvidia offers them with Ethernet upto 400GbE as well, same speed as EFA says on the label.