roy@phri.UUCP (Roy Smith) (02/20/86)
Is there any reason why an ethernet (thin or thick) cable can't be
branched? All the diagrams I see only show linear layouts with taps off
the main line. Will the following work? We plan on some extra runs that
don't have anything on them (yet); thus the branch with just a terminator.
Assuming these branches are legal at all, should the ends have just dust
caps instead of terminators?
*=======T========T===========T============X======X====*
| | | # #
3/50--+ * +---3/50 etc #
| 3/50---+ #
+---3/50 +---3/50 3/180
| |
* *
Key: * 50-Ohm terminator + BNC-tee connector
= Thick cable | Thin cable
X Ethernet tranceiver T N-tee connector with BNC adapter
--
Roy Smith, {allegra,philabs}!phri!roy
System Administrator, Public Health Research Institute
455 First Avenue, New York, NY 10016carl@hpcnof.UUCP (02/21/86)
> Is there any reason why an ethernet (thin or thick) cable can't be > branched? All the diagrams I see only show linear layouts with taps off > the main line. Will the following work? From my experience you will definitely get hosed if you try to tee a cable without using a repeater. It *might* work, but unreliably. You definitely want to use a repeater or other alternative. Carl Dierschow Hewlett-Packard Colorado Networks Division {ihnp4|hplabs}!hpfcla!hpcnof!c_dierschow
skip@ubvax.UUCP (Skip Addison Jr) (02/21/86)
In article <2239@phri.UUCP> roy@phri.UUCP (Roy Smith) writes: > > Is there any reason why an ethernet (thin or thick) cable can't be >branched? All the diagrams I see only show linear layouts with taps off > ... Yes, there is a reason why that won't work, in general. Just about anything can work, as those of the bubble-gum and bailing wire school of thought so often discover. But branching an Ethernet will not work reliably in general. The reason has to do with transmission line theory, maxwell's equations, or the law of parallel resistors :-), depending on your persuasion. Basically, the cable needs to appear to be one continuous length of cable. -- Skip Addison {lll-crg, decwrl, ihnp4}!amdcad!cae780!ubvax!skip
andre@nrcvax.UUCP (Andre Hut) (03/02/86)
In article <454@ubvax.UUCP> skip@ubvax.UUCP (Skip Addison Jr) writes: >In article <2239@phri.UUCP> roy@phri.UUCP (Roy Smith) writes: >> Is there any reason why an ethernet (thin or thick) cable can't be >>branched? All the diagrams I see only show linear layouts with taps off >> ... >Yes, there is a reason why that won't work, in general. Just about anything >can work, as those of the bubble-gum and bailing wire school of thought so >often discover. But branching an Ethernet will not work reliably in general. > >The reason has to do with transmission line theory, maxwell's equations, or >the law of parallel resistors :-), depending on your persuasion. Basically, >the cable needs to appear to be one continuous length of cable. Sorry Skip, that is wrong. The only rule is that there can not be more than two paths between any two stations. Each branch must also be terminated. -- ----------------------------------------------------------------------------- ihnp4-\ sdcsvax-\ \ Andre' Hut sdcrdcf!psivax!nrcvax!andre hplabs--/ / ucbvax!calma-/ Network Research Corporation 923 Executive Park Dr. Suite C Salt Lake City, Utah 84117 -----------------------------------------------------------------------------