| 摘要 |
A technique automatically configures the role of a router interface coupled to a synchronous data link control (SDLC) device, such as a physical unit (PU) station, of a computer network. When the router is activated and attached to a PU station over a communication link, it waits a predetermined period time before issuing any frames. A PU 2.1 or PU 4.0 station promptly initiates an exchange identification (XID) frame exchange upon being activated to determine its primary/secondary role according to the SDLC protocol. If no XID frames are received during the predetermined period, the router issues a null XID to the PU station, thereby forcing the PU station to respond with a configured XID identifying the station. If the PU station returns an XID0 frame, the router automatically configures the role of its interface to primary because a PU 2.0 device can only assume the role of a secondary.
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