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How It Works

InfiniBand addressing works in an environment that is compatible with Transfer Control Protocol/Internet Protocol addressing and is based on Version 6 of IP, which allows more addresses for network-linked devices "than atoms in the universe," Eunice said.

The large number of addresses ensures InfiniBands future scalability. One InfiniBand switch is expected to be able to communicate with a maximum 64,000 devices, but theres no reason that a switch cant use one of those connections to attach to another InfiniBand switch, multiplying the number of possible connections by another 64,000, according to Meier.

Such interconnections constitute what advocates call the "switched fabric" of an InfiniBand subnetwork. The PCI bus was a highway that carried messages from one point down a general-purpose path, and the more messages, the slower the traffic could move, IBMs Bradicich said. InfiniBand is more like a high-speed train, moving from one point to another through clearly defined switching stations. No matter how much traffic there is, it can move at the same speed.

Unlike a train, however, InfiniBand doesnt require a message to follow one route the way a train follows its tracks. With InfiniBand, alternative routes can be found around a failed device. In addition, InfiniBand makes it much easier to cluster Internet servers together, as in a Web server farm or group of database servers, Bradicich said.

While clusters of just two machines prevail today, InfiniBand is likely to make clusters of 10, 20 or 50 machines commonplace, Eunice said, because it standardizes a shared server interconnect. And given the distances InfiniBand links may cover, its conceivable that all the servers in an office building or on a small campus could be linked together in an InfiniBand cluster.

In addition, InfiniBand promises to do another task attractive to Internet server users: Allow users to connect large pools of storage to multiple servers over an InfiniBand connection. With InfiniBand, companies like Sun may be better able to compete with market leader EMCs Symmetrix disk arrays.

"Sun views storage as a feature of the server," Eunice said. The new standard, he said, will level the playing field among storage vendors, speeding up connections between various storage arrays and servers.