RDMA Transport Specification

Transport

The individual transport specifications allow NVM Express to isolate and independently evolve transports for evolving memory and fabric transports. The NVM Express® (NVMe®) 2.0 specifications define the theory of operations for transports in the NVMe Base specification and the mapping of specific transports to individual specifications.

What is the RDMA Transport specification?

The RDMA Transport specification uses Remote Direct Memory Access (RDMA) and enables data and memory to be transferred between computer and storage devices across a fabric network. RDMA is a way of exchanging information between two computers’ main memory in a network without involving the processor, cache, or OS of either computer. Because RDMA avoids the OS, it is a fast and low-overhead mechanism for transmitting data across a network.

As of August 2024, NVMe is a set of the following eleven specifications:

  • NVM Express® Base Specification, Revision 2.1
  • Command Set Specifications:
    • NVM Express® NVM Command Set Specification, Revision 1.1
    • NVM Express® NVMe Zoned Namespaces Command Set Specification, Revision 1.2
    • NVM Express® Key Value Command Set Specification, Revision 1.1
    • NVM Express® Subsystem Local Memory Command Set Specification, Revision 1.0
    • NVM Express® Computational Programs Command Set Specification, Revision 1.0
  • Transport Specifications:
    • NVM Express® NVMe over PCIe Transport Specification, Revision 1.1
    • NVM Express® RDMA Transport Specification, Revision 1.1
    • NVM Express® TCP Transport Specification, Revision 1.1
  • NVM Express® NVM Express Management Interface Specification, Revision 2.0
  • NVM Express® NVMe Boot Specification, Revision 1.1

The NVM Express® Base Specification, Revision 2.1 reorganizes sections to distinguish requirements on functionality common to PCIe® and Fabrics implementations, specific to PCIe implementations, and specific to Fabrics implementations.