Method and apparatus are described for improving
information transfer over
USB. In one approach, hub-based extension is realized wherein power is distributed using auxiliary wiring distinct from
signal and power wiring present in conventional
USB cabling. Additional signals allow optimization of power distribution for powering attached devices, and for detecting and handling illegal connection configurations. In another approach, improvements are realized through use of alternative signaling techniques which eschew reflective and high-speed common-mode signaling. Described are various configuration, media and
signal-protocol combinations, including implementations containing embedded hubs. Methods ensuring reliable
system behavior are also described, including determination of extension
path delay and use of topology-
enforcement hubs. In other approaches, further improvements are realized by allowing information exchanges to take longer than the nominal
timeout period, or by allowing host requests to be delayed for transmission until the extended
bus is available for use.