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InfiniBand (abbreviated IB) is a computer-networking communications standard used in high-performance computing that features very high throughput and very low latency. It is used for data interconnect both among and within computers. InfiniBand is also utilized as either a direct, or switched interconnect between servers and storage systems, as well as an interconnect between storage systems.
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As of 2014 it was the most commonly used interconnect in supercomputers. Mellanox and Intel manufacture InfiniBand host bus adapters and network switches, and in February 2016 it was reported that Oracle Corporation had engineered its own Infiniband switch units and server adapter chips for use in its own product lines and by third parties. Mellanox IB cards are available for Solaris, RHEL, SLES, Windows, HP-UX, VMware ESX, AIX. It is designed to be scalable and uses a switched fabric network topology.
As an interconnect, IB competes with Ethernet, Fibre Channel, and proprietary technologies such as Cray's Aries™.
The technology is promoted by the InfiniBand Trade Association.
Performance
Links can be aggregated: most systems use a 4X aggregate. 12X links are typically used for cluster and supercomputer interconnects and for inter-switch connections.
InfiniBand also provides RDMA capabilities for low CPU overhead.
Topology
InfiniBand uses a switched fabric topology, as opposed to early shared medium Ethernet. All transmissions begin or end at a channel adapter. Each processor contains a host channel adapter (HCA) and each peripheral has a target channel adapter (TCA). These adapters can also exchange information for security or quality of service (QoS).
Messages
InfiniBand transmits data in packets of up to 4 KB that are taken together to form a message. A message can be:
Physical interconnection
In addition to a board form factor connection, it supports both active and passive copper (up to 30 meters) and optical fiber cable (up to 10 km). QSFP connectors are used.
The Infiniband Association also specified the CXP copper connector system for speeds up to 120 Gbit/s over copper and active optical cables.
API
InfiniBand has no standard API. The standard only lists a set of verbs like ibv_open_device or ibv_post_send, which are abstract representations of functions or methods that must exist. The syntax of these functions is left to the vendors. The de facto standard software stack is that developed by OpenFabrics Alliance. It is released under two licenses GPL2 or BSD license for GNU/Linux and FreeBSD, and as WinOF under a choice of BSD license for Windows. It has been adopted by most of the InfiniBand vendors, for GNU/Linux, FreeBSD, and Windows.
History
InfiniBand originated in 1999 from the merger of two competing designs: Future I/O and Next Generation I/O. This led to the formation of the InfiniBand Trade Association (IBTA), which included Compaq, Dell, Hewlett-Packard, IBM, Intel, Microsoft, and Sun. At the time it was thought some of the more powerful computers were approaching the interconnect bottleneck of the PCI bus, in spite of upgrades like PCI-X. Version 1.0 of the InfiniBand Architecture Specification was released in 2000. Initially the IBTA vision for IB was simultaneously a replacement for PCI in I/O, Ethernet in the machine room, cluster interconnect and Fibre Channel. IBTA also envisaged decomposing server hardware on an IB fabric. Following the burst of the dot-com bubble there was hesitation in the industry to invest in such a far-reaching technology jump.