vd09+@andrew.cmu.edu (Vincent M. Del Vecchio) (12/05/90)
Many thanks to everyone who responded. I received a variety of suggestions, all of which basically fell into a few categories. Several people (Tom Seto (Seto@UNCAMULT.BITNET), Bill Westfield (BILLW@mathom.cisco.com), Del Riesenhuber (del@ads.com), and Max Tardiveau (root@nextserver.cs.stthomas.edu)) said that it is possible to simply connect the two networks together with the appropriate type of adapter, available for less than $20. I think that this is probably what we will try first, as it seems to be the simplest and is likely to require the smallest investment of time and money. Bill Westfield also commented, however: > It probably isn't wonderful from an electrical signal point of view, but > I've seen it work. As long as everyone knows that this is likely to be > a source of problems (so it becomes the first thing to remove when the > network breaks), it's certainly worth a try. And Max Tardiveau had similar points: > Theoretically, you can connect thick and thin Ethernet 'directly', i.e. > without a repeater. However, the connection has to be relatively > clean....Note that the total length of the network has to be reasonably > short for that to work. Also, Del Riesenhuber said that they (he wasn't sure whether this would be true in the general case) needed to use a router rather than a simple connector in order to run protocols other than TCP/IP (e.g. NetWare) over the PC half of the network. I am not sure whether this will be a problem for us or not (since, at the moment, our network isn't being > used for anything at all :-( ). A number of people mentioned using a PC with two ethernet cards as a router or bridge. This sounds like a viable solution in general, as I indicated in my original posting, because we probably have old PCs we can spare, and if we needed more ethernet cards, they are not that expensive. Several people (Mark Boyd (mark@ccvr1.cc.ncsu.edu) Tom Seto, Bill Westfield, Phil Green (pmgreen@rodan.acs.syr.edu)) mentioned PCRoute or the simpler (and almost certainly still sufficient for our needs) PCBridge, by Vance Morrison at Northwestern U, ftpable from accuvax.nwu.edu. This has the disadvantage that it requires Western Digital ethernet cards, but we might be able to afford two of those. Bill Nickless (nickless@elrond.cs.andrews.edu) mentioned KA9Q, ftpable from uunet or thumper.bellcore.com. While this package seems a little complicated, it sounds like it may do what we want, and I think it will work with the 3Com cards if we get packet drivers for them (which I understand are available from Clarkson). As a third basic alternative, some people (Bill Westfield, Cris Shuldiner (cws@ftp.com), Eric Durbin (ericd@ms.uky.edu), and Doug Nelson (08071TCP@MSU.BITNET)) suggested we might get new transceivers, or perhaps even just modify our old transceivers to put the unix boxes on thinnet. It seems like this is likely to be more expensive, and we will probably only try this if the first two solutions fail. A couple of these people also suggested that we get an ethernet repeater or router, but we have priced some of these things, and they really don't look like they're in our price range. If someone knows where we can get one of these things for < $1000, please tell me. Actually, the more important figure may be $250, which is a price estimate I have on the pair of Western Digital cards which would be needed for the PCBridge solution. Finally, Frank Actis (franka@hpctdlb.hp.com) mentioned an HP bridge, for ~$5000, and suggested: > Why not call your local HP sales office and see if HP would be > interested in an educational grant? While HP is most interested in > giving away things to colleges, it never hurts to try. We will probably at least check into this as well. As he says, it won't hurt to try. Again, thanks very much for all of the info. -Vince Del Vecchio (vd09@andrew.cmu.edu)
DMPM@DUKEMC.BITNET (James Dryfoos- PostMaster) (12/06/90)
I would like to comment on your thick to thin proposals. I would suggest using a repeater. The repeater will pass all protocols. You do not need a router. The repeater also will protect your thick wire network. One problem with thin wire is it is easily disrupted. Adding new connections requires breaking the cable, and simply sliding a pc on the desk top can cause the thin wire to go down. If you have a repeater the repeater will segment the thin from the thick and allow the thick to continue working while the thin is down. This has been very important to us as we find the thin not the most secure. You can add a couple of extra blank (not used) t connectors on the thin for future connections, but if you add too many you also add interference on the wire which may cause it to die. The repeater is a MAC layer device and is therefore protocol independant. Jim Dryfoos