Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site deepthot.UUCP Path: utzoo!watmath!deepthot!julian From: julian@deepthot.UUCP (Julian Davies) Newsgroups: net.lan Subject: Re: cheapernet? Message-ID: <323@deepthot.UUCP> Date: Fri, 15-Jun-84 12:25:56 EDT Article-I.D.: deepthot.323 Posted: Fri Jun 15 12:25:56 1984 Date-Received: Sat, 16-Jun-84 06:24:29 EDT References: <1259@sun.uucp> Organization: UWO CS, London Canada Lines: 21 At a presentation here by 3Com, it was explained that the 'thin cable' is lossier by a factor of 3, not 2, so that 1 foot of thin cable should be counted as 3 feet of thick-cable equivalent. A system with thick cable and only 3Com external transceivers can go to 1000m, so a thin cable segment can only go to 300m. However, the two can be combined in one 'segment' up to the 1000m "thick equivalent", provided there are only a few thickness transitions. Thick cable with less controlled transceivers is limited to 500m, they said. Another thing I learned and hadn't appreciated before is that the 'repeater' joining two cable segments is a bit-level repeater, not a frame-level buffering repeater, so there is an upper limit if 2500m and two repeaters between any pair of transceivers in a single network made from several segments. and *that* limit 2500m includes the connecting cables used at repeaters or in fibre-optic repeater connections. one can go beyond that limit if a full-fledged gateway buffering and retransmiting frames is used. Julian davies university of Western Ontario