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InfiniBand is an
architecture and specification for data flow between
processors and I/O devices that promises greater bandwidth
and almost unlimited expandability in tomorrow's computer
systems. In the next few years, InfiniBand is expected to
gradually replace the existing Peripheral Component
Interconnect (PCI)
shared-bus
approach used in most of today's personal computers and
servers. Offering throughput of up to 2.5 gigabytes
per second and support for up to 64,000 addressable devices,
the architecture also promises increased reliability, better
sharing of data between clustered processors, and built-in
security. InfiniBand is the result of merging two competing
designs, Future I/O, developed by Compaq, IBM, and
Hewlett-Packard, with Next Generation I/O, developed by Intel,
Microsoft, and Sun Microsystems. For a short time before the
group came up with a new name, InfiniBand was called System
I/O.
Existing PCs and server systems are hampered with an
inflexible and relatively slow internal data flow system,
including today's 64-bit, 66 MHz PCI bus. As the
amount of data coming into and flowing between components in
the computer increases, the existing bus system becomes a
bottleneck. InfiniBand provides a revolutionary new approach.
Instead of sending data in parallel (typically 32 bits at a
time, but in some computers 64 bits) across the backplane
bus (data path), InfiniBand specifies a serial (bit-at-a-time)
bus. Fewer PINs
and other electrical connections are required, saving
manufacturing cost and improving reliability. The serial bus
can carry multiple channels
of data at the same time in a multiplexing
signal. InfiniBand also supports multiple memory
areas, each of which can addressed by both processors and
storage devices.
Unlike the present I/O subsystem in a computer, InfiniBand
seems like a full-fledged network. The InfiniBand Trade
Organization describes the new bus as an I/O network and views
the bus itself as a switch
since control information will determine the route a given
message follows in getting to its destination address. In
fact, InfiniBand uses Internet Protocol Version 6 (IPv6)
with its 128-bit address, allowing an almost limitless amount
of device expansion.
With InfiniBand, data is transmitted in packets
that together form a communication called a message. A
message can be a remote direct memory access (RDMA) read or
write operation, a channel send or receive message, a
transaction-based operation (that can be reversed), or a multicast
transmission. Like the channel model many mainframe users are
familiar with, all transmission begins or ends with a channel
adapter. Each processor (your PC or a data center server, for
example) has what is called a host channel adapter
(HCA) and each peripheral device has a target channel
adapter (TCA). These adapters can potentially exchange
information that ensures security or work with a given Quality
of Service level.
The first products equipped for InfiniBand are expected to
be available in early 2001.
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Last updated on: Jun 05,
2001
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