DOBEIRNE@IRLEARN.BITNET (Dermot O'Beirne) (02/12/90)
Can anyone please let me know the 'relative' cost of the various components in tp ethernet systems as against thinnet, thick and fibre components. I am not talking about the actual cabling or its installation but sub-parts like terminators, PC cards, bridges, repeaters and hubs (presumably needed for tp). Thanks, Dermot O'Beirne
MOLTA@VAXB.ACS.UNT.EDU (02/13/90)
>Can anyone please let me know the 'relative' cost of the various components >in tp ethernet systems as against thinnet, thick and fibre components. I >am not talking about the actual cabling or its installation but sub-parts >like terminators, PC cards, bridges, repeaters and hubs (presumably needed >for tp). When comparing the relative costs of twisted-pair Ethernet to thinwire Ethernet, you will need to make sure you consider both initial costs of each system as well as recurring maintenance and management costs. Thinwire Ethernet will almost always be cheaper up front, but you have to affix some kind of cost component to reliability and diagnosis of problems. For example, every time I have to send a couple of people to a building on campus to troubleshoot a thinwire cabling problem, it costs the university money. In addition, there is some monetary value associated with the loss of productivity experienced by the people whose Ethernet is down. Finally, how do you attach a cost to the fact that Professor X can't reorganize his office a certain way because the thinwrire segment won't reach across the room without re- installing the cable segment. Unfortunately, these problems and their associated costs are difficult to predict in advance; all we can say for sure is that if you have large thinwire Ethernet segments, you will eventually develop problems. With twisted-pair, star topologies, you have greatly enhanced problem detection/isolation, superior network monitoring/management, and much more flexibility to reconfigure the physical layout of the network. Having said all of that, here are some cost components that I have begun to gather in dealing with two new building-wide twisted-pair Ethernets: Interface cards: In the short term, you will probably be able to purchase clone-quality thinwire Ethernet cards for less that twisted-pair cards. I've seen Novell NE-1000s for less than $150 each. Now that commodity Ethernet card vendors, such as Western Digital, have announced twisted pair cards, I anticipate that we will see discounted TP cards available for between $200 and $250 (the WD TP cards list for $349). We have been working with Cabletron, whose cards have some unique diagnostic and management features, and they have indicated that we would be looking at pricing of less than $250 on large quantity orders. Concentrators: The cost of concentrators is highly dependent on the features of the unit itself. A barebones TP concentrator without network management will probably run you about $150 per port, assuming you can swing a discount in the 25% range. More sophisticated systems with network management, such as those available from David Systems, Fibermux, Cabletron, Optical Data Systems, and Synoptics, will probably run between $200 and $300 per port discounted. Bridges: Some of the more sophisticated concentrators, such as those available from Cabletron and Synoptics, include options for the integration of a MAC-level bridge within the concentrator chassis itself. The incremental cost of $3500 to $4000 is usually about the same as for a high-performance stand-alone bridge. Since all of the concentrators include an AUI port, you can always use a stand-alone bridge connected directly to the concentrator if you want to go with a medium-performance bridge. As far as repeaters and terminators are concerned, they don't really apply in the TP environment since each concentrator port really includes repeater functions. One of the nice devices that Cabletron sells is a TP to thinwire converter that allows a twisted pair port to support up to 9 thinwire devices that are daisy-chained together. Of course, using this device forces you to give up some of the management/fault isolation capabilities inherent in TP Ethernet. I hope this helps and I'd be happy to discuss TP Ethernet issues in more detail with anyone who's interested. Dave Molta University of North Texas 817-565-2324