scp@bpa.BELL-ATL.COM (Steve Parowski) (11/30/89)
Thank you for the responses, I think that I will implement a thickwire backbone and twisted pair to workstations or A fiber backbone and twisted pair to workstations. Any pros/cons and hardware vendors that can provide this will be helpful.... Ethernet responses are listed below... Subject: Re: ETHERNET Installation HELP Organization: Boston U. Information Technology > > >I am building an ether net network and would like to use >twisted pair but I think the 100 meters is too limiting . > >Thin Net is a possibility but I do not like the intrusive cable tapping >feature.......... > >Thick wire looks great but the cable pull 8 floors might be difficult > >HELP!!!!!!! I'll do what I can. :-) > >The following is my topology... > > > > | ><_137'_______>|_________________***8th floor*****_____________ >^ >| >| >| >|122 feet >| >| >| >| >| >|<______38'__>___________**1st floor*** > | | > One of the nice things about Ethernet is that you have the choice of so many media and the opportunity to make so many more mistakes than you could otherwise hope to make. :-) I think you could exploit the strengths of a couple of Ethernet media and come up with something you would like. If you already have telephone wire and closets available, consider installing unshielded twisted pair (UTP) Ethernet multiport concentrators in or near your phone closets. Then you can exploit existing cable and you might not run into the 100 meter limit. You should have at least one closet per floor. Concentrators usually come modulo eight to twelve ports. Some include network management features. Wire the concentrators together with an intra-building backbone of thin or thick Ethernet. Limit the taps on this backbone to concentrators within the closets, so you can easily locate and look at the transceivers. You will find thin/thick cabling of this scale to be easy to manage. So, in brief, use UTP Ethernet for the stations and use thick or thin between the UTP concentrators. Kent England, Boston University Subject: Re: ETHERNET Installation HELP THICK CABLE: An 8 story drop is not all that bad as long as you have a straight shot down a Teleco or utility closet. We run 1600ft segments of thick coax all through our buildings which cover up to 7 floors in one segment. I recommend that you start on the top floor, drop the cable down to the first... run it around the first and then unspool enough to run it the rest of the way on the 8th floor. I prefer thick over thin for more than one floor operations. -rick crispin Subject: Re: ETHERNET Installation HELP I would use thick-wire for the riser cable making sure that it is accessible from each wiring closet on each floor. Either leave enough cable on each floor for multiple taps (cheapest) or plan on a multiport transceiver in each closet (best). Allocate enough space in each closet for star controllers (multiport repeaters) so that each office has its own dedicated point to point link. Use either twisted-pair or thin-wire. Any active components that I installed would either be manageable or would be upgradgeable to managed versions. Networks always grow much larger than anyone ever thought they would. If you're going to pull cable from each office to the wiring closets then why not investigate installing fiber at the same time? Dave Osterman LLNL 7000 East Ave MS L-72 Livermore, CA 94550 415.422.3499 osterman@snmp.ocf.llnl.gov Subject: Re: ETHERNET Installation HELP What about fiber? -----------fiber-modem--------------fiber-modem------------ ethernet ethernet Subject: Re: ETHERNET Installation HELP Organization: Defense Industrial Supply Center, Philadelphia, Pa Cc: Status: RO We are in the process now of doing a twisted pair network since we already have experienced the problems with thin-net. We still use thick coax for long runs through a single building and tap it in the departments where we need to connect nodes. We have studied the distance problem you cite however found we are well within the constraint. The 100 meters is from the concentrator to the workstation, and the twisted pair runs under the floor so there is virtually little vertical waste. As I under- stand it the twisted pair networks where designed knowning that 95+% of existing twisted pair runs that where installed by the phone companies are under this 100 meter limit to the punch down closets. >Thin Net is a possibility but I do not like the intrusive cable tapping >feature.......... You got that right! This becomes worst with adds, moves and changes you may need to make later -- with twisted pair all this is eliminated. > >Thick wire looks great but the cable pull 8 floors might be difficult > Do you plan to do this yourself? We had a cable contractor run a 1000' of thick coax down the length of our building within a week. Thick coax does not bend well so it should not be a problem in long straight runs. > >The following is my topology... > Looks like a piece of cake.. -- Ray Matrone {bpa,osu-cis!dsacg1}!discg1!rmatrone Internet: rmatrone%discg1.uucp@dsac.dla.mil Subject: ETHERNET Installation HELP To: scp@bpa.BELL-ATL.COM Status: RO <I am building an ether net network and would like to use <twisted pair but I think the 100 meters is too limiting . I would suggest a combination of Fiber as the backbone riser and twisted pair for your horizontal. The fiber gets you ready for FDDI if perfromance is a need and the TP gives you ease of installation with Ethernet products available today. When you do a fiber riser be certain to configure it in a star configuration, that is a fiber run to each floor repeater from a star on say the first floor. THis keeps your net running if you loose the wire to a repeater on one floor fro some reason. 3Com provides a TP repeater which can also use fiber modules made by Chipcom or Codenoll. I can send you more information if you would like. Reinier Tuinzing 3Com Corp 408 970-2085