Recent Developments

published paper

The Extended Sockets Interface for Accessing RDMA Hardware (PDF)
by Robert Russell, in PDCS, November 2008

new documentation

An EXS Overview (PDF)
by Robert Russell, November 2008

published paper

Implementation and Evaluation of iSCSI over RDMA (PDF)
by Ethan Burns and Robert Russell, in IEEE SNAPI, September 2008

About the Consortium

The UNH-IOL iWARP Testing Consortium, formed August 17, 2004, is an industry-supported organization that works with member companies to provide a neutral test environment and industry-accepted test methodologies to advance the interoperability of devices that implement the iWARP protocol family.

About iWARP

iWARP (for “internet Wide-Area RDMA Protocol”) allows computers anywhere in the world to communicate with each other using RDMA (remote direct memory access). RDMA, which has a longer history of use in local networks for such demanding applications as enterprise storage and clustered supercomputing, has recently become valuable for Internet applications as well. As network links increase in capacity to ten gigabits per second and beyond, RDMA becomes attractive because it removes what would otherwise be overwhelming network load from a computer's central processor.

iWARP traffic is designed to pass through the Internet like any other traffic, so no adaptations are needed in the conventional Internet infrastructure. However, each of the two computers at the endpoints does need the following special adaptations, which are all focused on eliminating wasteful copying of the transmitted data.

• hardware: a specially-made RDMA network interface card (RNIC) which is able to directly transmit from and receive to the motherboard memory bus (typically PCI Express) rather than from/to memory on the interface card itself, as is the case with conventional NICs
• software: operating system kernel adjustments to allow data to move directly between application memory and the RNIC without an intermediate move into operating-system kernel memory
• software: a driver to match the RNIC, exploiting the above two adaptations

Members of the UNH-IOL iWARP Consortium are typically vendors of these hardware and software adaptations. The work of the Consortium is to test their products for conformance to standards and for interoperability with each other.

(In addition to the adaptations listed above, an end computer could also emulate the hardware component (i.e., the RNIC) with software. This would allow one end computer to gain the advantages of RDMA without requiring the other end to invest in a hardware RNIC. Programmers at the UNH-IOL are currently developing such software emulation, which we call SoftWARP.)

For more details see our FAQ.