Which statement describes the target channel adapter in InfiniBand architecture?

The correct answer is B. In InfiniBand architecture, a Target Channel Adapter (TCA) is a type of channel adapter typically used in I/O devices or I/O units, not in host systems. Its role is to connect the I/O controller to the InfiniBand fabric, and that fabric connection is ordinarily made through an InfiniBand switch. NVIDIA’s InfiniBand terminology defines a TCA as a channel adapter usually used in I/O devices, while InfiniBand fabrics are composed of switches and channel adapter devices (HCA/TCA).

This eliminates the other options. A router in InfiniBand is used to connect different InfiniBand subnets, not to serve as the normal attachment point for an I/O controller. Cisco data center knowledge aligns with this architectural distinction: HCAs/TCAs attach endpoints to the fabric, while switches interconnect endpoints within a subnet and routers interconnect subnets. NVIDIA documentation on InfiniBand routing states that IB routers forward traffic between two or more IB subnets, which is a different function from a TCA.

Therefore, the target channel adapter is best described as providing the connection between the InfiniBand switch and the I/O controller.