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Article #13652Re: request for assistance (RJ-45 cables, coaxial cables)
From: Donald Becker
Date: Thu, 10 Sep 1998 00:00
Date: Thu, 10 Sep 1998 00:00
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In article <OD1gl9G39GA.251@upnetnews02.moswest.msn.net>, Andreas Gladisch <varon66@email.msn.com> wrote: >Can somebody please help me with the following simple questions? >(1) How many circuits are there in an RJ-45 cable? There are four two-wire twisted pairs. (There are many more "circuits", depending on your definition of circuit, but that's a useless number.) In Europe a sometime-used version called "STP" has a metallic screen similar to the foil around TV cable. The screen is not designed to carry current or signals, and is intended to shield the cable from interference. In reality it increases attenuation and couples more electrical noise to the pairs. While safety is rarely a problem, STP also increases the risk of humans encountering dangerous voltages. >(2) How many circuits in the RJ-45 cable are used in a twisted pair > network? Two pairs are active, one each for transmit and receive. The other two pairs are usually passively terminated at one or both ends to minimize noise. No other signals should be run on the two passive pairs. >(3) How many circuits does a coaxial cable contain? For typical coax, one. Perhaps you are really asking "Is it possible to run 10baseT over an old coax network." No, it's not. -- Donald Becker becker@cesdis.gsfc.nasa.gov USRA-CESDIS, Center of Excellence in Space Data and Information Sciences. Code 930.5, Goddard Space Flight Center, Greenbelt, MD. 20771 301-286-0882 http://cesdis.gsfc.nasa.gov/people/becker/whoiam.html
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X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: fa123,79b920088b17acae X-Google-Attributes: gidfa123,public X-Google-Thread: 1045e3,79b920088b17acae X-Google-Attributes: gid1045e3,public X-Google-Thread: 10669a,79b920088b17acae X-Google-Attributes: gid10669a,public From: becker@cesdis.gsfc.nasa.gov (Donald Becker) Subject: Re: request for assistance (RJ-45 cables, coaxial cables) Date: 1998/09/10 Message-ID: <6t8ukt$78f@yukon.gsfc.nasa.gov> X-Deja-AN: 389793689 References: <OD1gl9G39GA.251@upnetnews02.moswest.msn.net> Organization: NASA Goddard Space Flight Center -- Greenbelt, Maryland USA Newsgroups: ch.comp.networks,comp.os.linux.networking,de.comp.os.unix.networking