3Com 3C780 User Guide - Page 163

2 Glossary Concentrator DAC DAS Dotted decimal notation Downstream Dual counter-rotating ring Dual ring Dual homing A sophisticated multiplexer or hub device that has additional ports beyond those required for its own attachment to the main ring of an FDDI network. These additional ports are for attaching other FDDI nodes (including single attachment stations [SASs] and other concentrators) in a tree topology. Concentrators may be stand-alone (null attachment) and not connected to the main ring; they may support only the interconnection of a few SASs. Dual Attachment Concentrator. A concentrator with A and B ports for attachment to both the primary and secondary rings. Dual Attachment Station. A station with A and B ports for attachment to the primary ring only. The syntactic representation for a 32-bit integer that consists of four 8-bit numbers written in base 10 with periods (dots) separating them. The normal direction of data flow on a token ring network. Also, the adjacent station in the transmission (ring) path. A dual-ring LAN topology in which two separate fiber or copper cables provide signal paths on which information travels in opposite directions. The second ring provides a backup for the first ring in the event of failure of the first (primary) ring. A pair of counter-rotating logical rings. An FDDI redundant topology. This refers to one of two situations: in the first, a dual-MAC station is connected to (is homed on) both rings at the same time. The second situation involves redundant attachments of a dual-attached station or concentrator to the ring(s), with one attachment functioning as a backup link.