High Quality Content by WIKIPEDIA articles! DOCSIS Set-top Gateway (or DSG) is a specification describing how out of band data is delivered to a cable set-top box. Cable set-top boxes need a reliable source of out of band data for information such as program guides, channel lineups, and updated code images.DSG is an extension of the DOCSIS protocol governing cable modems, and applies equally to all versions of DOCSIS.The original DOCSIS protocol supports only two way connectivity. A cable modem that is unable to acquire an upstream channel will give up and resume scanning for new channels. Likewise, persistent upstream errors will cause a cable modem to "reinitialize its MAC" and scan for new downstream channels. This behavior is appropriate for traditional cable modems, but not for cable set-top boxes. A cable set-top box still needs to acquire its out of band data even if the upstream channel is impaired.

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