| Geographic Extension of HIPPI Channels via (2007) | |||||||||||||
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| The HIPPI channel, as defined by the ANSI standard, operates in a dual simplex fashion transmitting data at 800 Mb/s. The basic standard allows 25 meter separation between the sending and receiving channel endpoints as the defined connection medium is a "bundle " of twisted pair with each data line operating at 25 Mb/s. The standard also supports networked, i.e. switched, operation via the channel defined "I-field", (an information field), such that HIPPI channel end points can be connected and switched through an arbitrary mesh of physical channel inter-connections supported by HIPPI channel cross-bar switches. Switches with as many as thirty two channel ports have been realized. Further "extension " mechanisms are needed, however, to increase the twenty five meter distance limitation between channel connection points, be they channel end point to channel end point, channel endpoint to switch port, or switch port to switch port. Specification of one extension mechanism, i.e. "ad hoc serial HIPPI", is nearing completion. Serial HIPPI specifies how the twisted pair "bundled " data lines are to be carried over a pair of single mode fibers, each operating at 1.025 Gb/s, extending the maximum connection point separation from twenty five meters, to ten to forty kilometers over dark fiber, i.e. over fiber with no signal regeneration between end points. Viable geographically wide area connectivity can be achieved via use of the emerging carrier oriented synchronous digital hierarchy, i.e. SONET. More specifically the full duplex SONET STS 12c over OC-12 offering operating at 622 Mb/s with a payload of 600 Mb/s, offers a reasonable speed match with the HIPPI 800 Mb/s data transfer rate. (This device is also compatible with STM-4c in Europe), | |||||||||||||
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