From ejbehr@rs6000.cmp.ilstu.edu Thu May 2 23:45:42 1991 Received: from rs6000.cmp.ilstu.edu by plains.NoDak.edu; Thu, 2 May 91 23:45:35 -0500 Received: by rs6000.cmp.ilstu.edu (AIX 3.1/UCB 5.61/4.03) id AA04975; Thu, 2 May 91 23:46:55 -0500 From: ejbehr@rs6000.cmp.ilstu.edu (Eric Behr) Reply-To: ejbehr@rs6000.cmp.ilstu.edu (Eric Behr) Message-Id: <9105030446.AA04975@rs6000.cmp.ilstu.edu> Subject: Re: 10Base-T hubs (1) To: overby@plains.NoDak.edu Date: Thu, 2 May 91 23:46:55 PDT In-Reply-To: <9105030435.AA01898@plains.NoDak.edu>; from "Glen Overby" at May 2, 91 11:35 pm X-Mailer: ELM [version 2.3 PL11] Status: R Here is a summary of responses I received re. 10Base-T hubs and wiring. In our situation, arguments in favor of 10Base-T sound convincing. Distances are relatively short, new twisted pair is being pulled anyway, most stations will be in offices as opposed to labs, and our users are not terribly computer-conscious, so management and fault detection are quite important. Given the trends in pricing, thinnet is not as attractive as it was just a year or so ago. Eric PS. The confusion about "passive" hubs was caused by an Asante tech type, who told me that theirs was a "passive hub". part 1 ---------------------------------------------------------------------- Reply-To: mkd@cbnewsj.att.com Date: Wed, 3 Apr 91 09:01:13 EST From: mkd@mtunh.att.com (Mark K Darby) To: ejbehr@rs6000.cmp.ilstu.edu Subject: Re: 10Base-T hubs News-Path: att!linac!mp.cs.niu.edu!ux1.cso.uiuc.edu!rs6000.cmp.ilstu.edu!ejbehr > We're considering using our twisted pair wires for Ethernet. Hence tons of > questions, some of which are below: > > - aside from distance/no. of stations differences, is UTP inherenly less > reliable than thin/thick E-net? No. As a matter of fact, you can consider it more reliable in a sense that the 10BASE-T architecture, being point-to-point, can allow a network to remain active whena single station goes fubar, thanks to the REQUIRED auto- partition mechanism in the 10BASE-T hub device. If a station goes fubar or a break occurs on a stretch of thick/thin coax, all stations on that segment are essentially out of luck in working on the network. Also, 10BASE-T electrical/signal requirements are designed such that the sharing of services in a TP 25-pair sheath is possible without degradation of the 10BASE-T signals running through the sheath. > > - in a smallish network (30 nodes, less that 300 ft.) is a passive hub OK? > Price difference between active and passive hubs is substantial... The hub/repeater for 10BASE-T is MANDATED to be based on the multi-port repeater spec in 802.3 (i.e it must have retiming and regeneration capabilities, therefore it must be active). If it's passive, it's not 10BASE-T and therefore not standard. Period. In this case, it might be more cost effective to go to a 10BASE-2 thin ethernet network. > > - has anyone had any experience with the passive 12-port hub from Asante? No (at least not me). > > - is there any advantage to "cascading" hubs (attaching the next one to a > port in the previous one - you lose two ports) as opposed to putting both > directly on a thin/thick backbone and using all ports for the UTP star? Depends upon the placement of the nodes you wish to connect, the number of nodes you want to connect, the availability of AUI ports on the hubs the amount of money you want to spend, and the prospects for future network expansion. Having a thick(or thin) ethernet backbone is typical for networks is which clusters of nodes are farther apart than 10BASE-T's maximum of 100meters. If they are all close together and you have no need to consider future expansion then cascading would seem better. However, as you mentioned, you lose two ports when you cascade. If you needed those two ports to connect up one or two more nodes in your network, then obtaining another 12-port hub to connect up only two nodes would be a cost issue. > > - (must be obvious...) does 10Base-T *have* to use star topology? That's the way the standard is written. > If so, then (troubleshooting aspects set aside) I save maybe $500 in > thinwire cabling costs but I lose $1000+ on a hub... I think that > 10Base-T's economic advantages are a bit overblown given the current > prices; am I right? A lot of the advantages of 10BASE-T center upon the use of pre-existing wiring. If your installation requires new wiring, then you lose that advantage. Then the cost of troubleshooting/managing a 10BASE-T plays a significant role in the advantages of 10BASE-T networks over traditional thick/thin ethernet networks. 10BASE-T has become a commodity market. Expect prices to get lower as competition increases. The LAN industry is one of the few growth markets right now, and 10BASE-T has played a MORE THAN SIGNIFICANT role in that growth. > > Thanks very much for answers/opinions. E. Glad to help. > -- > Eric Behr, Illinois State University, Mathematics Department > Internet: ejbehr@rs6000.cmp.ilstu.edu Bitnet: ebehr@ilstu Mark K. Darby AT&T StarLAN Network Hardware Development mkd@mtung.att.com ---------------------------------------------------------------------- Reply-To: german@uxh.cso.uiuc.edu Date: Wed, 3 Apr 91 10:36:26 -0600 From: Gregory German To: ejbehr@rs6000.cmp.ilstu.edu >Orig-To: ejbehr@rs6000.cmp.ilstu.edu (Eric Behr) >Subject: Re: 10Base-T hubs >Newsgroups: comp.dcom.lans >References: <1991Apr03.004515.12021@rs6000.cmp.ilstu.edu> In comp.dcom.lans you write: >We're considering using our twisted pair wires for Ethernet. Hence tons of >questions, some of which are below: Just a note that I have have hundreds of nodes on 10baseT now and have been using some since Oct 1989 before the standard was finalized. >- aside from distance/no. of stations differences, is UTP inherenly less >reliable than thin/thick E-net? Not really. The unshield nature of UTP makes is more vulnerable to electro- magnetic interference, but that affects the distance you can run, not the speed of the signal. A well designed network with either system will work fine. >- in a smallish network (30 nodes, less that 300 ft.) is a passive hub OK? >Price difference between active and passive hubs is substantial... I do not know what you mean by passive hub? All hubs are active repeaters with 10baseT. We have used equipment from Cabletron, Plexcom, David Systems and 3Com and evaluated some by other vendors, but have not gotten one in from Asante' yet. We have used some Asante' cards for the Mac with the other hubs though. 10baseT is a standard and I have yet to find any vendor's product that does not interoperate with what we use. >- has anyone had any experience with the passive 12-port hub from Asante? >- is there any advantage to "cascading" hubs (attaching the next one to a >port in the previous one - you lose two ports) as opposed to putting both >directly on a thin/thick backbone and using all ports for the UTP star? There are several ways you can have larger networks: Multiple hubs off a coax backbone. (standalone hubs) Cascading hubs off of master hub. (Plexcom) Active backplane in the Chassis that interconnects for you. (Cabletron) You may get an arguement from the vendor, but I consider Cascading to add an extra unpopulated segment and repeater towards your 4 repeaters in any given path limitation. I still use it where convenient, but keep the rules in mind. >- (must be obvious...) does 10Base-T *have* to use star topology? >If so, then (troubleshooting aspects set aside) I save maybe $500 in >thinwire cabling costs but I lose $1000+ on a hub... I think that >10Base-T's economic advantages are a bit overblown given the current >prices; am I right? Most vendors have 10baseT to thin-coax products. This allows you to have 10 stations on a thin-wire segment after a 10baseT run, but other than repeating or bridging off the end of your 10baseT run it is designed to be point to point. Where I find 10baseT economical is when I design for an entire building. I like to bring a connection from every room in the building to a central location and terminate it in a patch pannel. I then locate my repeater hub at this location. When I have this I can add ANY office to ANY network I care to configure. Each office is immune to what the office next to it does with its connection unlike daisy chained thin-coax. Changing and office from one network to another is done by moving a jumper. You can have AppleTalk, Ethernet, Token Ring or serial conenctions through the same distribution system. If you pay for the network monitoring options you can look at everything remotely. >Thanks very much for answers/opinions. E. >-- >Eric Behr, Illinois State University, Mathematics Department >Internet: ejbehr@rs6000.cmp.ilstu.edu Bitnet: ebehr@ilstu -- Greg German (german@sonne.CSO.UIUC.EDU) (217-333-8293) US Mail: Univ of Illinois, CSO, 1304 W Springfield Ave, Urbana, IL 61801 Office: 129 Digital Computer Lab., Network Design Office ---------------------------------------------------------------------- Reply-To: ckollars@East.Sun.COM Date: Wed, 3 Apr 91 10:47:30 EST From: ckollars@East.Sun.COM (Chuck Kollars - Sun Technical Marketing - Boston) To: ejbehr@rs6000.cmp.ilstu.edu Subject: Re: 10Base-T hubs Newsgroups: comp.dcom.lans Organization: Sun Microsystems, Billerica MA In article <1991Apr03.004515.12021@rs6000.cmp.ilstu.edu> you write: >We're considering using our twisted pair wires for Ethernet. Hence tons of >questions, some of which are below: > >- aside from distance/no. of stations differences, is UTP inherenly less >reliable than thin/thick E-net? I believe it's _more_ reliable. It includes an integrity check on each wire. An outage in one place doesn't usually bring down the whole net. And many hubs have substantial network monitoring and/or fault isolation logic built into them. > >- in a smallish network (30 nodes, less that 300 ft.) is a passive hub OK? >Price difference between active and passive hubs is substantial... > >- has anyone had any experience with the passive 12-port hub from Asante? > >- is there any advantage to "cascading" hubs (attaching the next one to a >port in the previous one - you lose two ports) as opposed to putting both >directly on a thin/thick backbone and using all ports for the UTP star? > >- (must be obvious...) does 10Base-T *have* to use star topology? >If so, then (troubleshooting aspects set aside) I save maybe $500 in >thinwire cabling costs but I lose $1000+ on a hub... I think that >10Base-T's economic advantages are a bit overblown given the current >prices; am I right? If you look only at purchase cost of the equipment, UTP still costs nearly as much a thicknet and more than thinnet. But if you include installation costs (unless you have slave student labor available), UTP costs a lot less. Any telephone service dweeb can plug together UTP, but thinnet and thicknet require snaking these "unusual" wires through walls. If you include ongoing maintenance costs (again unless you have slave labor available) and downtime costs (unless you don't care about downtime), UTP is even more cost- effective. > >Thanks very much for answers/opinions. E. You're welcome. I always like invitations to throw in my $0.02. >-- >Eric Behr, Illinois State University, Mathematics Department >Internet: ejbehr@rs6000.cmp.ilstu.edu Bitnet: ebehr@ilstu -- chuck kollars Sun Technical Marketing, located in Sun's Boston Development Center ---------------------------------------------------------------------- >From root Wed Apr 3 15:01:20 1991 Reply-To: craigo@mercury.TSD.3Com.COM Date: Wed, 3 Apr 91 13:00:06 -0800 From: Craig Owen Message-Id: <9104032100.AA13589@mercury.TSD.3Com.COM> To: ejbehr@rs6000.cmp.ilstu.edu Subject: Re: 10Base-T hubs Newsgroups: comp.dcom.lans In-Reply-To: <1991Apr03.004515.12021@rs6000.cmp.ilstu.edu> Organization: 3Com Corporation Cc: Status: RO In article <1991Apr03.004515.12021@rs6000.cmp.ilstu.edu> you write: >We're considering using our twisted pair wires for Ethernet. Hence tons of >questions, some of which are below: > >- aside from distance/no. of stations differences, is UTP inherenly less >reliable than thin/thick E-net? Possibly. If you have a high-noise environment there might be problems, but 10BASE-T does have quite a bit of noise immunity built in. I've never seen a problem with too much noise and I've designed three 10BASE-T adapters. > >- in a smallish network (30 nodes, less that 300 ft.) is a passive hub OK? >Price difference between active and passive hubs is substantial... > I don`t know anything about passive hubs but in a smallish network coax is probably cheaper since you don't need a repeater or hub. >- has anyone had any experience with the passive 12-port hub from Asante? > >- is there any advantage to "cascading" hubs (attaching the next one to a >port in the previous one - you lose two ports) as opposed to putting both >directly on a thin/thick backbone and using all ports for the UTP star? > Most hubs would require a special cable (crossed over) to go between 10BASE- T ports. Also, remember that you can only have a maximum of four repeaters between any two nodes. >- (must be obvious...) does 10Base-T *have* to use star topology? >If so, then (troubleshooting aspects set aside) I save maybe $500 in >thinwire cabling costs but I lose $1000+ on a hub... I think that >10Base-T's economic advantages are a bit overblown given the current >prices; am I right? > 10BASE-T must use a star topology. The main advantage of this is network management in large networks. This is why I suggest above that coax would be cheaper for your small network which probably doesn't need network management. 3Com also sells a product called "PairTamer" which runs over twisted pair but allows you to put up to 30 nodes on one port of your hub or eliminate the hub altogether. Other companies also sell baluns that might accomplish the same function. The main disadvantage of this is that it's a proprietary system that is only supported by one company. >Thanks very much for answers/opinions. E. >-- >Eric Behr, Illinois State University, Mathematics Department >Internet: ejbehr@rs6000.cmp.ilstu.edu Bitnet: ebehr@ilstu ---------------------------------------------------------------------- >From root Thu Apr 4 00:17:34 1991 Received: from gacvx2.gac.edu by rs6000.cmp.ilstu.edu (AIX 3.1/UCB 5.61/4.03) id AA04363; Thu, 4 Apr 91 00:17:25 -0600 Reply-To: DAN@gacvx2.gac.edu Date: Thu, 4 Apr 1991 00:11 CST From: Dan Boehlke Subject: Re: 10Base-T hubs To: ejbehr@rs6000.cmp.ilstu.edu Message-Id: <9A193BB3000030A0@gacvx2.gac.edu> X-Vms-To: IN%"ejbehr@rs6000.cmp.ilstu.edu" Status: RO In article <1991Apr03.004515.12021@rs6000.cmp.ilstu.edu>, ejbehr@rs6000.cmp.ilstu.edu (Eric Behr) writes: > We're considering using our twisted pair wires for Ethernet. Hence tons of > questions, some of which are below: > > - aside from distance/no. of stations differences, is UTP inherenly less > reliable than thin/thick E-net? I have found UTP to be more reliable than thin ethernet. We have been using thin ethernet in several building. I have found that the BNC connectors on thin ethernet do not take wear well. I have had faculty rearrange their office and take out an entire segment consisting of several offices, not because they are being malicious but just because they don't know better. In classrooms I use a $75 connector and cable from AMP that shorts out inside the wall when the cable is removed. Most faculty offices have a $8 wall plate with two BNC connectors on it. The real solutions are to use more expensive connectors, or change to a star topology (DEC recommends this in their local area networking books.) I have also found that the physics department likes to extend their cable on their own. When I finally caught up with them they had a network that was quite a bit over the 30 connections and 300 meters allowed in a thin ethernet. A unix computer on their segment could not be reliably accessed by users on other segments. The physics departments excuse was that I didn't make the rules clear enough and just how were they suppose to know the length of the cable. They still paid for the repeater and earned my ire. The faculty in the building I have using UTP ethernet have not been able to mess up the network yet. I have had some stations go bad in the lab due to strained cables, but a longer cable took care of that. > - in a smallish network (30 nodes, less that 300 ft.) is a passive hub OK? > Price difference between active and passive hubs is substantial... > > - has anyone had any experience with the passive 12-port hub from Asante? I don't know that active and passive hubs is a good way to describe the difference between the types of hubs. All hubs are essentially multi-port repeaters some have incorporated bridges or a high speed internal bus. The more expensive hubs usually include managment capabilities. This allows monitoring all the ports from one workstation anywhere on the ethernet. Most managment hubs allow the managment station to get the number of packets/bytes transfered through the port and also an error count. Many allow the management station to turn ports on and off. I have built a 60 computer network using the Asante hubs. They work well. They have no management capability. I did run into some problems with the Asante hub not being able to tell a shorted cable from a cable with a computer at the other end. I was told by another use of the hubs that this is because Asante used a single chip UTP ethernet controler that was designed for workstation and as uses the same link integrity pulse as a workstation, thus the loopback caused by the short could not be detected. I don't know if other hubs have the same problem, if they do then something more than a single LED is needed to signal an error. Having managment would help. I also had a problem with a 25 pair cable that was multipled to another punch block this cable caused the hub to go throught a cycle of powerup-error-reset-error-reset-... The whole hub did this making all the workstations on it unuseable. I have seen token ring hubs blow fuses in similar situation. More expensive hubs just cut out the malfunctioning ports. Fixing the cabling problem caused the hub to function normally. In a small network the Asante hub is adiquate. I do not plan to use it in the new Computer Science/Physics/Academic Computing building. There are more than 200 computers in this new building on three floors to start with, the building it being wired by the same contractor that is doing the phones and is going to be capable of supporting about 500 computers before we need to add wire. I am planning to use management hubs in this building. There is also significant need for traffic management in this building. > - is there any advantage to "cascading" hubs (attaching the next one to a > port in the previous one - you lose two ports) as opposed to putting both > directly on a thin/thick backbone and using all ports for the UTP star? I use thin ethernet between the hubs. This reduces the repeater count and allows me to use the cascading feature in a room with one UTP port. I can plug in a hub and have 11. With RJ45 cords a quick network can be build in any classroom. We will be using this this summer as the summer programs here will out number our available computer labs since three labs will be closed while they are moving to the new building. I is also hand if the instructor wants to bring more than one computer into a classroom. Even in the new building I will probably have a couple of Asante hubs available for this use. > - (must be obvious...) does 10Base-T *have* to use star topology? > If so, then (troubleshooting aspects set aside) I save maybe $500 in > thinwire cabling costs but I lose $1000+ on a hub... I think that > 10Base-T's economic advantages are a bit overblown given the current > prices; am I right? I compare 10BASE-T to a thin ethernet star. A thin eithernet bus does not have the same reliability characteristics as a star. It does have to be a strict star where the thin ethernet star can have multiple computers on each segment. I think you will find multi-port thin ethernet repeaters to as expensive as UTP hubs. I also use the UTP wiring for more than just ethernet, we also run token ring and rs-232 over it. It is also possible to run AS/400 twinax terminals and 3270 terminals over it using baluns. Arcnet is another possibility. I have found that a well built thin ethernet network and a UTP ethernet are about the same price per port. By well built I mean one with about the same reliability as the UTP network. I also strongly recommend purchasing a portable cable tester like the ones sold by MicroTest. They have been valuable in finding both thin ethernet and UTP cable problems. Also a cheap PC software package like Ether Monitor from Brightworks or NetCure/NetMon (available on the net) is very helpfull for locating problems. -- Dan Boehlke Internet: dan@gac.edu Campus Network Manager BITNET: dan@gacvax1.bitnet Gustavus Adolphus College St. Peter, MN 56082 USA Phone: (507)933-7596 -- Forwarded-By: Dan Boehlke Internet: dan@gac.edu Campus Network Manager BITNET: dan@gacvax1.bitnet Gustavus Adolphus College St. Peter, MN 56082 USA Phone: (507)933-7596 ---------------------------------------------------------------------- Article 4379 of comp.dcom.lans: Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!news.cs.indiana.edu!samsung!olivea!uun et!vtserf!GroupW.cns.vt.edu!jcrowder From: jcrowder@GroupW.cns.vt.edu (Jeff Crowder) Newsgroups: comp.dcom.lans Subject: Re: 10Base-T hubs Message-ID: <1548@vtserf.cc.vt.edu> Date: 3 Apr 91 15:37:15 GMT References: <1991Apr03.004515.12021@rs6000.cmp.ilstu.edu> Sender: news@vtserf.cc.vt.edu Distribution: usa Organization: Va Tech Communications Resources Lines: 30 In article <1991Apr03.004515.12021@rs6000.cmp.ilstu.edu> ejbehr@rs6000.cmp.ilstu.edu (Eric Behr) writes: >- (must be obvious...) does 10Base-T *have* to use star topology? >If so, then (troubleshooting aspects set aside) I save maybe $500 in >thinwire cabling costs but I lose $1000+ on a hub... I think that >10Base-T's economic advantages are a bit overblown given the current >prices; am I right? I think this is a salient point. I keep wanting to go with 10Base-T for all the obvious reasons (we already have good UTP installed, the aesthetics are much better, cable fault isolation and tolerance, management, etc.). But I just can't get the numbers to add up. If you read the rags and listen to the poop, it sounds like EVERYBODY is doing 10Base-T for ALL their new installations. But its kind of funny; net managers I actually talk to aren't moving so fast. I think a lot of the hype has been invented. You know, if you're a hardware manufacturer of ethernetworking type stuff (or a seller of such), this thinwire coax thing just doesn't leave much room for revenue. Heck, you can install a small thinwire ethernet with absolutely NO electronic gizmos whatsoever. These smooth talkers and network-conference-showers have every reason to push 10Base-T as hard as they can. The good news is that this should enhance competition and lead to very rapid price incentives for customers like me. The per port cost is already on the downswing. But until it drops quite a bit more, I won't be able to justify it in most cases... Jeff Crowder Virginia Tech jcrowder@GroupW.cns.vt.edu ---------------------------------------------------------------------- end of part 1 -- Eric Behr, Illinois State University, Mathematics Department =====> ejbehr@rs6000.cmp.ilstu.edu <===== From ejbehr@rs6000.cmp.ilstu.edu Thu May 2 23:46:00 1991 Received: from rs6000.cmp.ilstu.edu by plains.NoDak.edu; Thu, 2 May 91 23:45:53 -0500 Received: by rs6000.cmp.ilstu.edu (AIX 3.1/UCB 5.61/4.03) id AA04470; Thu, 2 May 91 23:47:14 -0500 From: ejbehr@rs6000.cmp.ilstu.edu (Eric Behr) Reply-To: ejbehr@rs6000.cmp.ilstu.edu (Eric Behr) Message-Id: <9105030447.AA04470@rs6000.cmp.ilstu.edu> Subject: Re: 10Base-T hubs (2) To: overby@plains.NoDak.edu Date: Thu, 2 May 91 23:47:14 PDT In-Reply-To: <9105030435.AA01898@plains.NoDak.edu>; from "Glen Overby" at May 2, 91 11:35 pm X-Mailer: ELM [version 2.3 PL11] Status: R 10Base-T summary part 2 ---------------------------------------------------------------------- Article 4381 of comp.dcom.lans: Newsgroups: comp.dcom.lans Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!news.cs.indiana.edu!msi.umn.edu!noc.MR .NET!jhereg!andrew From: andrew@jhereg.osa.com (Andrew C. Esh) Subject: Re: 10Base-T hubs Message-ID: <1991Apr3.161219.19343@jhereg.osa.com> Organization: Open Systems Architects, Inc., Mpls, MN References: <1991Apr03.004515.12021@rs6000.cmp.ilstu.edu> Distribution: usa Date: Wed, 3 Apr 1991 16:12:19 GMT In article <1991Apr03.004515.12021@rs6000.cmp.ilstu.edu> ejbehr@rs6000.cmp.ilstu.edu (Eric Behr) writes: >We're considering using our twisted pair wires for Ethernet. Hence tons of >questions, some of which are below: > >- aside from distance/no. of stations differences, is UTP inherenly less >reliable than thin/thick E-net? > UTP? Unshielded Twisted Pair, I assume. Since the inclusion of Link Pulse, I have found 10baseT to be much more reliable. One bad node doesn't affect any of the others, and the bad one is obvious. The wiring can be tested with a continuity tester, and it either works or it doesn't. Shielded wire is prone to problems that are marginal, and hard to locate without a Cable Scanner or a Time Domain Reflectometer. Connectors are much easier with 10baseT, and the distribution blocks and wiring schemes are ones that any telephone contractor can handle. >- in a smallish network (30 nodes, less that 300 ft.) is a passive hub OK? >Price difference between active and passive hubs is substantial... > >- has anyone had any experience with the passive 12-port hub from Asante? By the way, 384 feet (100 meters) is the limit for 10baseT, so 300 feet is not what I would call small. Passive and active hubs? I didn't know there was such a thing as a passive hub. Either way, the wiring is the same, so I would wire it, and then get a cheap hub on evaluation. If it runs, go for it. Be sure it is advertised as 10baseT. Ones I have tried out or helped beta test are David, Xyplex, ODS, and others. Please tell me about the active and passive deal though. This is interesting. I have no experience with Assante. > >- is there any advantage to "cascading" hubs (attaching the next one to a >port in the previous one - you lose two ports) as opposed to putting both >directly on a thin/thick backbone and using all ports for the UTP star? Lose two ports? If you are connecting two "out" ports together, you will have problems. To cascade, you need to connect an out port of the parent, to the AUI port of the child, with a 10BaseT transceiver. Without the tree heirarchy, the timing gets all crunched and one or both of the hubs will stop working until the problem is corrected. Also, I would not cascade more than two levels. Although I have not tried it, I have had experience with time delay problems with other types of hubs if there are many cascades. You need to figure a loss budget for the retransmission time, and see if it stays within the net specifications. > >- (must be obvious...) does 10Base-T *have* to use star topology? >If so, then (troubleshooting aspects set aside) I save maybe $500 in >thinwire cabling costs but I lose $1000+ on a hub... I think that >10Base-T's economic advantages are a bit overblown given the current >prices; am I right? > Yes, 10baseT has to be star, just like telephones. When you consider costs, compare the cost per foot of wire, connectors, wiring blocks, manpower for installation, and the rental or purchase of test equipment to certify that the net is correctly installed. A Pair Tester is a lot cheaper than a Cable Scanner, and a four year old can operate it. Maintenance should also be figured. I have found Thin net to be prone to connector trouble after a few months getting kicked around under the desk. UTP is less sensitive to this sort of thing. >Thanks very much for answers/opinions. E. >-- >Eric Behr, Illinois State University, Mathematics Department >Internet: ejbehr@rs6000.cmp.ilstu.edu Bitnet: ebehr@ilstu -- Andrew C. Esh andrew@osa.com Open Systems Architects, Inc. Minneapolis, MN 55416-1528 So much System, (612) 525-0000 so little CPU time... ---------------------------------------------------------------------- Article 4383 of comp.dcom.lans: Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!news.cs.indiana.edu!sdd.hp.com!usc!app le!netcom!jbreeden From: jbreeden@netcom.COM (John Breeden) Newsgroups: comp.dcom.lans Subject: Re: 10Base-T hubs Message-ID: <1991Apr3.164611.4088@netcom.COM> Date: 3 Apr 91 16:46:11 GMT References: <1991Apr03.004515.12021@rs6000.cmp.ilstu.edu> Distribution: usa Organization: Netcom - Somewhere in the S.F. Bay Area Lines: 59 In article <1991Apr03.004515.12021@rs6000.cmp.ilstu.edu> ejbehr@rs6000.cmp.ilstu.edu (Eric Behr) writes: >We're considering using our twisted pair wires for Ethernet. Hence tons of >questions, some of which are below: > >- aside from distance/no. of stations differences, is UTP inherenly less >reliable than thin/thick E-net? > No (I can hook up just as many stations using UDP as thin/thicknet). >- in a smallish network (30 nodes, less that 300 ft.) is a passive hub OK? >Price difference between active and passive hubs is substantial... > If you are using a "passive" hub, it's not 10baseT. The standard calls for hubs that are active repeaters. If you decide to use "passive" hubs, you'll save money but a) you're not 10baseT and b) you're not "reliable". One of the things that makes 10baseT reliable is the active nature of the hubs (ie: multiport repeater function - packet re-generation). > >- is there any advantage to "cascading" hubs (attaching the next one to a >port in the previous one - you lose two ports) as opposed to putting both >directly on a thin/thick backbone and using all ports for the UTP star? > No, you can attach hubs off of coax, chain hub to hub or star hubs off of a single hub or any combination. >- (must be obvious...) does 10Base-T *have* to use star topology? >If so, then (troubleshooting aspects set aside) I save maybe $500 in >thinwire cabling costs but I lose $1000+ on a hub... I think that >10Base-T's economic advantages are a bit overblown given the current >prices; am I right? > Yes, 10baseT must be in a star configuration (it's in the standard). There is nothing that stops you from using a bus configuration (other than mechanical, you need to flip wire pairs to make it work). You loose the "reliability" of 10baseT without the hubs (packet regeneration, port jamming on bad packets, station isolation, "added-value vendor" hub management etc). 10baseT's economic advantage is'nt in the installation (that rumor got started with the "cost savings" of using existing phone wiring, which considering the type and condition of the wire installed may not be the case. The "cost savings" is the ease of trouble reporting, isolation and management due to the a) star configuration and b) management and fault isolation inherent in the hubs. If you are looking for "cheap" - use thinnet. -- John Robert Breeden, jbreeden@netcom.com, apple!netcom!jbreeden, ATTMAIL:!jbreeden ------------------------------------------------------------------- "The nice thing about standards is that you have so many to choose from. If you don't like any of them, you just wait for next year's model." ---------------------------------------------------------------------- Article 4387 of comp.dcom.lans: Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!uwm.edu!rpi!zaphod.mps.ohio- state.edu!casbah.acns.nwu.edu!casbah.acns.nwu.edu!asteiner From: asteiner@casbah.acns.nwu.edu (Albert Steiner) Newsgroups: comp.dcom.lans Subject: Re: 10Base-T hubs Message-ID: <1991Apr3.225739.29828@casbah.acns.nwu.edu> Date: 3 Apr 91 22:57:39 GMT References: <1991Apr03.004515.12021@rs6000.cmp.ilstu.edu> Sender: news@casbah.acns.nwu.edu (Mr. News) Distribution: usa Organization: Northwestern University ACNS Lines: 14 Nntp-Posting-Host: moses.acns.nwu.edu In article <1991Apr03.004515.12021@rs6000.cmp.ilstu.edu> ejbehr@rs6000.cmp.ilstu.edu (Eric Behr) writes: > - has anyone had any experience with the passive 12-port hub from Asante? No experience with Asante, but Asante, SMC, David Volksnet and some other cheap (<$1000) hubs have no management as well as other cutting other corners. It's not that they are passive. ----------------------------------------- asteiner@casbah.acns.nwu.edu Albert Steiner, Academic Computing and Networking, Northwestern University, Evanston, IL 60208 708-491-4056 ---------------------------------------------------------------------- Article 4390 of comp.dcom.lans: Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!uwm.edu!wuarchive!zaphod.mps.ohio- state.edu!rpi!crdgw1!uunet!hayes!msieweke From: msieweke@hayes.uucp Newsgroups: comp.dcom.lans Subject: Re: 10Base-T hubs Message-ID: <3901.27f9e38a@hayes.uucp> Date: 3 Apr 91 14:15:38 GMT References: <1991Apr03.004515.12021@rs6000.cmp.ilstu.edu> Distribution: usa Organization: Hayes Microcomputer Products, Norcross, GA Lines: 51 In article <1991Apr03.004515.12021@rs6000.cmp.ilstu.edu>, ejbehr@rs6000.cmp.ilstu.edu (Eric Behr) writes: > We're considering using our twisted pair wires for Ethernet. Hence tons of > questions, some of which are below: > > - aside from distance/no. of stations differences, is UTP inherenly less > reliable than thin/thick E-net? What is reliable? Our most frequent problem with our thinwire segments is people disconnecting their equipment and not putting back the jumper. This brings down the net for everyone on the same cable. Our thickwire xceiver cables frequently come out of the back of the equipment. So far (5 months) we have had no problems with our UTP segments. If someone screws up his/her machine, no one else is affected. Also, with Synoptics equipment our UTP traffic is easier to manage. > - in a smallish network (30 nodes, less that 300 ft.) is a passive hub OK? > Price difference between active and passive hubs is substantial... I don't know the difference. I have seen TP hubs for about $150 per port. Is there another type besides this? > - (must be obvious...) does 10Base-T *have* to use star topology? > If so, then (troubleshooting aspects set aside) I save maybe $500 in > thinwire cabling costs but I lose $1000+ on a hub... I think that > 10Base-T's economic advantages are a bit overblown given the current > prices; am I right? > Eric Behr, Illinois State University, Mathematics Department > Internet: ejbehr@rs6000.cmp.ilstu.edu Bitnet: ebehr@ilstu Yes, 10BaseT is always physically a star. Its advantage is that you can run it off of existing wiring (if it meets spec). You save the cost of running new wire (very expensive if contracted out). You brush off the troubleshooting aspects as though they weren't a consideration. How much is your time worth? 10BaseT eliminates several potential problems and will save you time every month that you use it. It's the gift that keeps on giving. :-) In my experience only the people in a government or university are short- sighted enough to ignore the time savings. This is not intended as an insult. I worked for Georgia Tech for 7 years, and every purchase had to be justified on tangible cost. No one took the time to investigate the _people_ costs of any purchase decision. Usually quality wasn't an obvious factor in the decision either. I hope this helps. -- Mike Sieweke ...!uunet!hayes!msieweke Hayes Microcomputer Products msieweke@hayes.uucp Norcross, Georgia hayes!msieweke@uunet.uu.net ---------------------------------------------------------------------- Article 4439 of comp.dcom.lans: Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!uwm.edu!zaphod.mps.ohio- state.edu!samsung!uunet!shl!phil From: phil@shl.com (Phil Trubey) Newsgroups: comp.dcom.lans Subject: Re: 10Base-T hubs Message-ID: <1991Apr08.171237.19978@shl.com> Date: 8 Apr 91 17:12:37 GMT References: <1991Apr03.004515.12021@rs6000.cmp.ilstu.edu> <1548@vtserf.cc.vt.edu> Distribution: usa Organization: SHL Systemhouse Inc. Lines: 44 In article <1548@vtserf.cc.vt.edu> jcrowder@GroupW.cns.vt.edu (Jeff Crowder) writes: >In article <1991Apr03.004515.12021@rs6000.cmp.ilstu.edu> ejbehr@rs6000.cmp.ilstu.edu (Eric Behr) writes: >>- (must be obvious...) does 10Base-T *have* to use star topology? >>If so, then (troubleshooting aspects set aside) I save maybe $500 in >>thinwire cabling costs but I lose $1000+ on a hub... I think that >>10Base-T's economic advantages are a bit overblown given the current >>prices; am I right? > >I think this is a salient point. I keep wanting to go with 10Base-T for >all the obvious reasons (we already have good UTP installed, the >aesthetics are much better, cable fault isolation and tolerance, >management, etc.). But I just can't get the numbers to add up. > >If you read the rags and listen to the poop, it sounds like EVERYBODY is >doing 10Base-T for ALL their new installations. But its kind of funny; >net managers I actually talk to aren't moving so fast. I think a lot of the >hype has been invented. You know, if you're a hardware manufacturer of >ethernetworking type stuff (or a seller of such), this thinwire coax >thing just doesn't leave much room for revenue. Heck, you can install a >small thinwire ethernet with absolutely NO electronic gizmos whatsoever. >These smooth talkers and network-conference-showers have every reason to >push 10Base-T as hard as they can. The good news is that this should >enhance competition and lead to very rapid price incentives for >customers like me. As others have pointed out, the cost savings aren't in physical capital costs - they are in people time saved from not having to fix and diagnose broken segments. This is a *major* cost for any network over a few dozen nodes. Add to this the fact that the dozens of LAN users won't experience network outages and you have large cost *savings* going to 10BaseT for most environments. As fas as the hype being invented, every new installation that I've dealt with (I work for a systems integrator) in the last year has been 10BaseT. The *only* place where I would recommend coax is in a lab environment where the machines are close together and don't move (ever), in a computer room connecting a few hosts together, or for a demo setup where you want to connect a few machines together for an on site demo. -- Phil Trubey | Internet: phil@shl.com SHL Systemhouse Inc. | UUCP: ...!uunet!shl!phil 50 O'Connor St., Suite 501 | Phone: 613-236-6604 x667 Ottawa, Ontario, Canada | Fax: 613-236-2043 ---------------------------------------------------------------------- Article 4441 of comp.dcom.lans: Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!uwm.edu!rpi!crdgw1!uunet!vtserf!GroupW.cns.vt.ed u!jcrowder From: jcrowder@GroupW.cns.vt.edu (Jeff Crowder) Newsgroups: comp.dcom.lans Subject: Re: 10Base-T hubs Message-ID: <1582@vtserf.cc.vt.edu> Date: 8 Apr 91 19:59:03 GMT References: <1991Apr03.004515.12021@rs6000.cmp.ilstu.edu> <1548@vtserf.cc.vt.edu> <1991Apr08.171237.19978@shl.com> Sender: news@vtserf.cc.vt.edu Distribution: usa Organization: Va Tech Communications Resources Lines: 44 In article <1991Apr08.171237.19978@shl.com> phil@shl.com (Phil Trubey) writes: >>>thinwire cabling costs but I lose $1000+ on a hub... I think that >>>10Base-T's economic advantages are a bit overblown given the current >>>prices; am I right? >> >>I think this is a salient point. I keep wanting to go with 10Base-T for >>all the obvious reasons (we already have good UTP installed, the >>aesthetics are much better, cable fault isolation and tolerance, >>management, etc.). But I just can't get the numbers to add up. >As others have pointed out, the cost savings aren't in physical >capital costs - they are in people time saved from not having to >fix and diagnose broken segments. This is a *major* cost for any >network over a few dozen nodes. Add to this the fact that the dozens Well, I can appreciate that a manageable hub should provide better fault isolation and diagnostic capabilities. In real terms, however, we've had only 3 physical layer failures which required dispatching a diagnostician within the last 14 months on a campus wide network connecting several thousand machines. Thinwire coax *installed properly* (i.e. good stress relief and careful connector installation) is quite reliable. Of course, a modicum of user training is recommended; it does not help to have a geology professor unplug the cable from the tee on his machine. I might also mention that the vast majority of responses I've received via e-mail have indicated that the authors had already come the more or less the same conclusion I had. (threads of paranoia showing thru) >As fas as the hype being invented, every new installation that I've dealt >with (I work for a systems integrator) in the last year has been 10BaseT. >The *only* place where I would recommend coax is in a lab environment Do you SELL the hubs you install by any chance ... ??? In any event, I'll bet you haven't helped out with many installations at state supported universities in states where very scarce funds are being channelled out of education and into a presidential campaign fund... >Phil Trubey | Internet: phil@shl.com Jeff Crowder, Network Guy and Grass Mower Virginia Tech jcrowder@GroupW.cns.vt.edu ---------------------------------------------------------------------- Article 4443 of comp.dcom.lans: Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!uwm.edu!spool.mu.edu!uunet!shl!phil From: phil@shl.com (Phil Trubey) Newsgroups: comp.dcom.lans Subject: Re: 10Base-T hubs Message-ID: <1991Apr09.021426.12241@shl.com> Date: 9 Apr 91 02:14:26 GMT References: <1548@vtserf.cc.vt.edu> <1991Apr08.171237.19978@shl.com> <1582@vtserf.cc.vt.edu> Distribution: usa Organization: SHL Systemhouse Inc. Lines: 29 In article <1582@vtserf.cc.vt.edu> jcrowder@GroupW.cns.vt.edu (Jeff Crowder) writes: >>As fas as the hype being invented, every new installation that I've dealt >>with (I work for a systems integrator) in the last year has been 10BaseT. >>The *only* place where I would recommend coax is in a lab environment > >Do you SELL the hubs you install by any chance ... ??? Yes, however we don't have exclusive distributorships with any particular product - we can markup Ethernet transceivers as well as we can 10BaseT hubs (on fixed price contracts). Interestingly enough, the reason for the majority of our 10BaseT installations is that our customers *ask* for it. > In any event, >I'll bet you haven't helped out with many installations at state >supported universities in states where very scarce funds are being >channelled out of education and into a presidential campaign fund... Stripped of the jabs, you're quite right. Universities tend to view labour as cheap and capital equipment as expensive. Most operating companies operate exactly the opposite way 'round. At least that's what I've found after working in both environments... -- Phil Trubey | Internet: phil@shl.com SHL Systemhouse Inc. | UUCP: ...!uunet!shl!phil 50 O'Connor St., Suite 501 | Phone: 613-236-6604 x667 Ottawa, Ontario, Canada | Fax: 613-236-2043 ---------------------------------------------------------------------- Article 4450 of comp.dcom.lans: Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!uwm.edu!spool.mu.edu!snorkelwacker.mit.edu!stanf ord.edu!leland.Stanford.EDU!Panther.Stanford.EDU!morgan From: morgan@Panther.Stanford.EDU (RL "Bob" Morgan) Newsgroups: comp.dcom.lans Subject: Re: 10Base-T hubs Message-ID: <1991Apr9.181721.15560@leland.Stanford.EDU> Date: 9 Apr 91 18:17:21 GMT References: <1548@vtserf.cc.vt.edu> <1991Apr08.171237.19978@shl.com> <1582@vtserf.cc.vt.edu> Sender: news@leland.Stanford.EDU (Mr News) Distribution: usa Organization: Networking Systems, Stanford University Lines: 80 Re 10Base-T: >As others have pointed out, the cost savings aren't in physical >capital costs - they are in people time saved from not having to >fix and diagnose broken segments. Hmm, my numbers show that 10Base-T is cheaper in almost every case (excepting those special cases of student labs and such that benefit from big-time daisy-chaining), even before the less immediate wins of using the structured cabling, etc. The cheapest thinnet MPR we've found has 9 ports (8 thin + 1 AUI) and runs about $1300 = $162.50 per thinnet port. The cheapest 10Base-T MPR has 14 ports (12 T + 1 thin + 1 AUI) and they want to sell it to us for the remarkable price of $700 = $58.33 per T port. A $100 win per port right off the bat. Lest you think this is a fluke, there are multiple vendors beating down our doors wanting to sell 10Base-T MPRs for around $900/12 = $75/port. Now cabling. My rule of thumb for contractor-installed thinnet in existing office space is about $100/office for quick & dirty, $150 for nice-looking (ie all in wiremold, etc). This isn't really affected much by whether you daisy-chain or not, since most of the cost is in the connectors and the time spent in the rooms and stringing the cable, not in the cable itself. Our on-campus telephone people, who support their operation entirely by user fees, are willing to do the wiring part of installing 10Base-T (ie, mounting punchblocks and cross-connects and labelling and any futzing with the jack that might be required) for $50 per circuit plus a $150 setup per job. We also choose to use a 110 block with RJ-45s mounted in it for jumpering to the MPR, which runs $100 or so. BTW, I haven't found an existing telephone circuit here yet that couldn't run 10Base-T acceptably (but then we haven't put in that many yet). 10Base-T Ethernet cards are only a few dollars more than thinnet these days. Jumper cables (wall outlet to computer) cost about the same for the two methods. So, comparing variable costs for an 8-station network (which puts thinnet in the best light): Thin: Repeater: $1300 Cable installation: 800 ---- 2100 10Base-T: Repeater: 700 Cable installation: 650 ---- 1350 So 10Base-T wins already, not even considering that we have 4 ports left over, we didn't have to get contractor bids, users didn't have to get their offices disrupted, moves and changes are much easier, etc. Even if all this weren't already compelling enough, an enormous win in our situation is that our on-campus telephone people are prepared to install these kinds of nets using their existing techs who already know how to handle twisted pair cable. This simply wasn't the case for thinnet. We're working out the procedures now so they can just take the whole process and run with it. So the *biggest* cost savings of all (IMHO) is that these networks can be installed en masse by readily-available, well-trained telephone people; you no longer need to use hard-to-find, expensive computer-network types who'd rather spend all their time sending news articles 8^). I'd like to see the numbers of those who say thinnet is cheaper. Again, I'll believe you if you're mostly installing student labs and such, but here at least those are mostly done already. The challenge is giving network access to every single office on campus, and that's where 10Base-T wins big. - RL "Bob" Morgan Networking Systems Stanford ---------------------------------------------------------------------- Article 4454 of comp.dcom.lans: Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!uwm.edu!rpi!zaphod.mps.ohio- state.edu!mips!news.cs.indiana.edu!msi.umn.edu!noc.MR.NET!jhereg!andrew From: andrew@jhereg.osa.com (Andrew C. Esh) Newsgroups: comp.dcom.lans Subject: Re: 10Base-T hubs Message-ID: <1991Apr9.221136.12326@jhereg.osa.com> Date: 9 Apr 91 22:11:36 GMT References: <1991Apr08.171237.19978@shl.com> <1582@vtserf.cc.vt.edu> Distribution: usa Organization: Open Systems Architects, Inc., Mpls, MN Lines: 33 In article <1582@vtserf.cc.vt.edu> jcrowder@GroupW.cns.vt.edu (Jeff Crowder) writes: >In article <1991Apr08.171237.19978@shl.com> phil@shl.com (Phil Trubey) writes: > >>As fas as the hype being invented, every new installation that I've dealt >>with (I work for a systems integrator) in the last year has been 10BaseT. >>The *only* place where I would recommend coax is in a lab environment Only a lab environment? You must realize that some sites are more spread out than what 10baseT can reach. Sure, it will work for one floor of a small to medium sized building, but sheer physics drives you up into ThinNet, ThickNet, and Fiber when the physical seperation between nodes is great. 10baseT just doesn't go more than 400 ft. The company I work for is called upon to design nets for buildings up to a quarter MILE on a side. 10baseT is great for an office area, but you need something else for distance. > >Do you SELL the hubs you install by any chance ... ??? In any event, >I'll bet you haven't helped out with many installations at state >supported universities in states where very scarce funds are being >channelled out of education and into a presidential campaign fund... > >>Phil Trubey | Internet: phil@shl.com > >Jeff Crowder, Network Guy and Grass Mower >Virginia Tech >jcrowder@GroupW.cns.vt.edu The company I work for is "vendor inspecific" for just this reason. :-) -- Andrew C. Esh andrew@osa.com Open Systems Architects, Inc. Minneapolis, MN 55416-1528 (612) 525-0000 Practicing the OSI Standard ---------------------------------------------------------------------- Article 4444 of comp.dcom.lans: Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!uwm.edu!zaphod.mps.ohio- state.edu!sdd.hp.com!hplabs!hpcc05!hpsciz!paul From: paul@hpsciz.sc.hp.com (Paul Mooney) Newsgroups: comp.dcom.lans Subject: Re: 10baseT Installation costs Message-ID: <900003@hpsciz.sc.hp.com> Date: 8 Apr 91 21:34:55 GMT References: <40993@cup.portal.com> Organization: Hewlett-Packard, Santa Clara, CA Lines: 12 Interesting ... One really must define "administrative costs." The major disadvantage of coax is the bus topology. At HP, where the user community cannot function when the LAN is down, StarLAN makes sense even if the initial installation costs are higher. Paul Mooney Network Services Hewlett Packard ---------------------------------------------------------------------- end of part 2 -- Eric Behr, Illinois State University, Mathematics Department =====> ejbehr@rs6000.cmp.ilstu.edu <===== From ejbehr@rs6000.cmp.ilstu.edu Thu May 2 23:46:15 1991 Received: from rs6000.cmp.ilstu.edu by plains.NoDak.edu; Thu, 2 May 91 23:46:07 -0500 Received: by rs6000.cmp.ilstu.edu (AIX 3.1/UCB 5.61/4.03) id AA04989; Thu, 2 May 91 23:47:27 -0500 From: ejbehr@rs6000.cmp.ilstu.edu (Eric Behr) Reply-To: ejbehr@rs6000.cmp.ilstu.edu (Eric Behr) Message-Id: <9105030447.AA04989@rs6000.cmp.ilstu.edu> Subject: Re: 10Base-T hubs (3) To: overby@plains.NoDak.edu Date: Thu, 2 May 91 23:47:27 PDT In-Reply-To: <9105030435.AA01898@plains.NoDak.edu>; from "Glen Overby" at May 2, 91 11:35 pm X-Mailer: ELM [version 2.3 PL11] Status: R 10Base-T summary part 3 ---------------------------------------------------------------------- Article 4455 of comp.dcom.lans: Xref: rs6000.cmp.ilstu.edu comp.dcom.lans:4455 comp.protocols.tcp-ip:7409 Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!uwm.edu!spool.mu.edu!mips!news.cs.indiana.edu!ms i.umn.edu!noc.MR.NET!jhereg!andrew From: andrew@jhereg.osa.com (Andrew C. Esh) Newsgroups: comp.dcom.lans,comp.protocols.tcp-ip Subject: Re: 10BaseT installation Message-ID: <1991Apr9.224333.13034@jhereg.osa.com> Date: 9 Apr 91 22:43:33 GMT Organization: Open Systems Architects, Inc., Mpls, MN Lines: 56 Well, the boss put the kaibosh on the 10baseT soliloquy, so all I can do is comment on what you folks are talking about. No paper. Something about having to make money and selling information being our business, and all that. I suppose I can say a few things though. 10baseT is easier to install, requires less experience to connectorize, and is more fault tolerant than coax. It is not, as far as we can tell, being hyped by the box builders to generate sales, since we see a legitimate application for it. If you are going to do-it-yourself, make sure you are using cable that is really rated for 10baseT. I have seen so many wierdo cable type from non-descript manufacturers that does no do the job. This cheap stuff is exactly what the cable vendor and your boss with the checkbook are going to choose for you, so be ready with information. Don't even settle for a written guarantee from the cable vendor that it's good wire, since such a guarantee can rarely cover all the trouble and downtime necessary to replace bad cable. Don't go over spec. You need a certain number of twists per foot, and you can't run it further than 100 meters, so stick with it. Fudge, and you pay the price, or more specifically, you pay people like me to come fix it. Cards? We have had trouble with a certain vendor's card. My advice is: It's still early in the game. A few vendors still have cards that don't cut it. Get an in house demonstration from the vendor. They'll do it for free, if they think you're going to buy some cards. Run some data back and forth across them (a process I call flossing), and see if they work okay. The same goes for hubs. Usually a vendor will let you have a demo unit for a week. For PCs, you can use a 3c503 card with a small 10baseT transceiver plugged into the AUI port, and it runs just fine. 10baseT transceivers are getting smaller and cheaper. We have some that are about the size of a deck of playing cards cut in half. They're great. Be careful of EMI. About all I can say is that it gets into 10baseT more than the other cable types. It comes from some interesting places, many of which are common in an office environment. Test equipment? Yes. Use a pair tester. Use a cable scanner. That's about all I can say about that. Want some philosophy? 10baseT, ThinNet, ThickNet, and Fiber are all here to stay. They all have their applications, and none can completely replace any of the others. Add 10baseT to you list of solutions to apply. Networking is growing as we speak. There is a lot of work and discovery and development out there waiting to happen. I started out in Software Engineering, but now I have made the switch to networking, and I travel all seven layers of the OSI stack. I love it. Have fun ... -- Andrew C. Esh andrew@osa.com Open Systems Architects, Inc. Minneapolis, MN 55416-1528 (612) 525-0000 Practicing the OSI Standard ---------------------------------------------------------------------- Article 4460 of comp.dcom.lans: Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!news.cs.indiana.edu!samsung!zaphod.mps.ohio- state.edu!rpi!clarkson!grape.ecs.clarkson.edu!nelson From: nelson@sun.soe.clarkson.edu (Russ Nelson) Newsgroups: comp.dcom.lans Subject: Re: 10Base-T hubs Message-ID: Date: 10 Apr 91 02:35:24 GMT References: <1548@vtserf.cc.vt.edu> <1991Apr08.171237.19978@shl.com> <1582@vtserf.cc.vt.edu> <1991Apr9.181721.15560@leland.Stanford.EDU> Sender: usenet@grape.ecs.clarkson.edu Reply-To: nelson@clutx.clarkson.edu (aka NELSON@CLUTX.BITNET) Distribution: usa Organization: Clarkson University, Potsdam NY Lines: 24 In-Reply-To: morgan@Panther.Stanford.EDU's message of 9 Apr 91 18:17:21 GMT In article <1991Apr9.181721.15560@leland.Stanford.EDU> morgan@Panther.Stanford.EDU (RL "Bob" Morgan) writes: Thin: Repeater: $1300 Cable installation: 800 ---- 2100 10Base-T: Repeater: 700 Cable installation: 650 ---- 1350 Perhaps I'm being too stupid here, but why do you need a repeater for an 8-station network? Why not hook them all up to the same cable? In that case, you have $800 for Thin vs $1350 for 10Base-T. -- --russ I'm proud to be a humble Quaker. It's better to get mugged than to live a life of fear -- Freeman Dyson I joined the League for Programming Freedom, and I hope you'll join too. ---------------------------------------------------------------------- Article 4461 of comp.dcom.lans: Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!uwm.edu!spool.mu.edu!snorkelwacker.mit.edu!stanf ord.edu!leland.Stanford.EDU!Panther.Stanford.EDU!morgan From: morgan@Panther.Stanford.EDU (RL "Bob" Morgan) Newsgroups: comp.dcom.lans Subject: Re: 10Base-T hubs Message-ID: <1991Apr10.035143.15862@leland.Stanford.EDU> Date: 10 Apr 91 03:51:43 GMT References: <1582@vtserf.cc.vt.edu> <1991Apr9.181721.15560@leland.Stanford.EDU> Sender: news@leland.Stanford.EDU (Mr News) Distribution: usa Organization: Networking Systems, Stanford University Lines: 61 > Perhaps I'm being too stupid here, but why do you need a repeater > for an 8-station network? Why not hook them all up to the same > cable? Well, if you've been reading comp.dcom.lans, the benefits of structured wiring have been explained at length. But this is indeed just the sort of question that those of us who install these things for a living have to answer on a daily basis. You're right, it isn't obvious. So here are the answers in easy-to-understand terms. 1. I didn't say so in my previous note, but the main point of putting in a network around here (and at almost any large institution these days, I'll bet) isn't to hook the machines to themselves, it's to hook them to the campus net (that is, to the Internet). So your proposed single run of thinnet has to connect to the building backbone in any case, which means a repeater. I'll admit I can't explain it, but I can get a 12-port 10Base-T repeater these days for about the same price as a traditional 2-port AUI-only repeater. 2. Where are these 8 stations anyway? As I said before, if they're in one room, sure, use thinnet. But if, as is the usual case, they're scattered around the floor of your medium-to-large building, then the "single cable" ends up hopping from room to room, crossing the hall, going around the corner, and doubling back to catch the one at the end of the hall. Maybe you're lucky and it's still only 450 feet. Then they get two more computers in two different offices (and yes, they *always* get more computers eventually). Someone looks up in the ceiling and finds where the cable runs kind of near the one office, cuts it and adds a loop. The other one is sort of near the end of the daisy-chain, so they just add to the end. How long is the cable now? Where are its connectors that will fail over time? Who bought the new cable that was spliced in, and why didn't they notice that it was 53 ohms, not 50 (they're lucky it wasn't 75)? So eventually the thing breaks down, and after weeks of cursing and head-scratching, they call in the network guys, who look around, shake their heads, and say: what you should do is buy a MPR and install some home runs to it. That way you'll have a manageable cable plant that is relatively immune to the weird things that people do to nets, and that provides an obvious growth path for future installers. 3. If those 8 stations are typical office PCs these days, they're probably worth a total of $20,000 or so. If they're fancy Unix boxes, the total may be over $100,000. If the people using them are getting paid for their time, the total may be a couple of hundred dollars an hour (of course, if they're just grad students ... 8^). Isn't it worth spending a extra few hundred dollars, adding at most 3 or 4 percent to the total cost of this networked computer system, to make the network as reliable as it can possibly be? So, the point is: no matter whether you're installing thinnet or twisted-pair or fishing line, it's almost always worth it to install a structured wiring plant. And once you've decided to do that, *if* you can use your existing structured telephone cable plant, then 10Base-T is cheaper by a long shot. No hype. - RL "Bob" Morgan Networking Systems Stanford ---------------------------------------------------------------------- Article 4467 of comp.dcom.lans: Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!news.cs.indiana.edu!spool.mu.edu!uunet!keinstr!b rinich From: brinich@keinstr.uucp (Mark Brinich) Newsgroups: comp.dcom.lans Subject: Re: 10Base-T hubs Message-ID: <1991Apr10.132856.8077@keinstr.uucp> Date: 10 Apr 91 13:28:56 GMT Article-I.D.: keinstr.1991Apr10.132856.8077 References: <1548@vtserf.cc.vt.edu> <1991Apr08.171237.19978@shl.com> <1582@vtserf.cc.vt.edu> Distribution: usa Organization: Keithley Instruments, Cleveland, Ohio Lines: 18 In article <1582@vtserf.cc.vt.edu> jcrowder@GroupW.cns.vt.edu (Jeff Crowder) writes: > >Well, I can appreciate that a manageable hub should provide better fault >isolation and diagnostic capabilities. In real terms, however, >we've had only 3 physical layer failures which required dispatching a >diagnostician within the last 14 months on a campus wide network >connecting several thousand machines. Thinwire coax *installed >properly* (i.e. good stress relief and careful connector installation) >is quite reliable. Of course, a modicum of user training is >recommended; it does not help to have a geology professor unplug the >cable from the tee on his machine. > I thought I'd throw in my 2 cents worth, as I have looked at this issue both at my current position, and in my previous life. Given budget constraints, it seems that coax, properly installed, is the way to go. In addition to this AMP (along with Black Box, DEC, etc.)has a very good wiring system that does away with all the bad traits of coax. With this wiring scheme you can unplug your Ethernet cable either at the wall connector they supply or at your workstation without bringing down your ethernet segment. Properly installed this also eliminates user access to the coax itself. Thus you have eliminated all the bad traits of thin coax. UTP still has the advantage of isolating a problem quickly, but with AMP's wiring system you still have the capability of removing a station without affecting the rest of the Ethernet, just as you do with UTP. I'd be a full supporter of UTP if it weren't so expensive/node for equipment. In fact if I were putting in new cabling in a building, I'd put in both thin and UT P. That way if UTP ever comes down in price, you can use it. But of course by the time that happens 10mbit/sec is going to be too slow for everyone, and you'll be looking at something else by then. -- Mark Brinich voice mail(or maybe the real live thing)216 498-2821 e-mail uunet!keinstr!brinich Keithley Instruments 28775 Aurora Rd. Cleveland, Ohio 44139-1891 ---------------------------------------------------------------------- Article 4470 of comp.dcom.lans: Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!uwm.edu!bionet!agate!ucbvax!decwrl!stanford.edu! leland.Stanford.EDU!Panther.Stanford.EDU!morgan From: morgan@Panther.Stanford.EDU (RL "Bob" Morgan) Newsgroups: comp.dcom.lans Subject: Re: 10Base-T hubs Message-ID: <1991Apr10.172643.26334@leland.Stanford.EDU> Date: 10 Apr 91 17:26:43 GMT References: <1991Apr08.171237.19978@shl.com> <1582@vtserf.cc.vt.edu> <1991Apr10.132856.8077@keinstr.uucp> Sender: news@leland.Stanford.EDU (Mr News) Distribution: usa Organization: Stanford University Lines: 13 > Given budget constraints, it seems that coax, properly installed, > is the way to go. In addition to this AMP (along with Black Box, > DEC, etc.)has a very good wiring system that does away with all the > bad traits of coax. Hmm, I don't remember the price of the AMP system exactly, but as I recall it was on the order of $50/outlet for the fancy connectors and patch cables. Given budget constraints, who would pay to have this put in? Given that 10Base-T repeaters are $60/port, where's the cost savings? - RL "Bob" ---------------------------------------------------------------------- Article 4471 of comp.dcom.lans: Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!uwm.edu!zaphod.mps.ohio- state.edu!rpi!news-server.csri.toronto.edu!utzoo!henry From: henry@zoo.toronto.edu (Henry Spencer) Newsgroups: comp.dcom.lans Subject: Re: 10Base-T hubs Message-ID: <1991Apr10.183625.27228@zoo.toronto.edu> Date: 10 Apr 91 18:36:25 GMT References: <1991Apr08.171237.19978@shl.com> <1582@vtserf.cc.vt.edu> <1991Apr10.132856.8077@keinstr.uucp> <1991Apr10.172643.26334@leland.Stanford.EDU> Organization: U of Toronto Zoology Lines: 18 In article <1991Apr10.172643.26334@leland.Stanford.EDU> morgan@Panther.Stanford.EDU (RL "Bob" Morgan) writes: >Hmm, I don't remember the price of the AMP system exactly, but as I >recall it was on the order of $50/outlet for the fancy connectors and >patch cables... We looked at it, briefly, and decided it was unattractive. Too expensive, and of course the length of the patch cable counts double against your thinwire length limit (a non-trivial concern here because we've got a big building with networking enthusiasts thinly scattered). It's a cheap (in both senses of the word) imitation of having a thickwire cable with transceivers clamped on and transceiver cables running out to customers. I increasingly think that thinwire makes sense for wiring a densely-populated room or a minimal configuration, but not for large-scale building networks. You want either thick coax with transceivers or UTP. -- And the bean-counter replied, | Henry Spencer @ U of Toronto Zoology "beans are more important". | henry@zoo.toronto.edu utzoo!henry ---------------------------------------------------------------------- Article 4473 of comp.dcom.lans: Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!news.cs.indiana.edu!know!zaphod.mps.ohio- state.edu!wuarchive!uunet!vtserf!GroupW.cns.vt.edu!jcrowder From: jcrowder@GroupW.cns.vt.edu (Jeff Crowder) Newsgroups: comp.dcom.lans Subject: Re: 10Base-T hubs Message-ID: <1593@vtserf.cc.vt.edu> Date: 10 Apr 91 21:09:58 GMT References: <1991Apr08.171237.19978@shl.com> <1582@vtserf.cc.vt.edu> <1991Apr9.181721.15560@leland.Stanford.EDU> Sender: news@vtserf.cc.vt.edu Distribution: usa Organization: Va Tech Communications Resources Lines: 64 In article <1991Apr9.181721.15560@leland.Stanford.EDU> morgan@Panther.Stanford.EDU (RL "Bob" Morgan) writes: > >Re 10Base-T: >Hmm, my numbers show that 10Base-T is cheaper in almost every case >The cheapest thinnet MPR we've found has 9 ports (8 thin + 1 AUI) and > ... > (a bunch of strange mumblings) > ... >So, comparing variable costs for an 8-station network (which puts >thinnet in the best light): > >Thin: >Repeater: $1300 >Cable installation: 800 > ---- > 2100 >10Base-T: >Repeater: 700 >Cable installation: 650 > ---- > 1350 > >So 10Base-T wins already, not even considering that we have 4 ports >Even if all this weren't already compelling enough, an enormous win in >our situation is that our on-campus telephone people are prepared to >install these kinds of nets using their existing techs who already >know how to handle twisted pair cable. This simply wasn't the case >for thinnet. We're working out the procedures now so they can just (Sorry if this thread is getting wearisome but I think this warrants response...) Uh, excuse me Bob but what the hell are you talking about? Of COURSE you daisy chain offices together with thinwire. I mean, after all you have more than 600' to play with. You'd have to be NUTS to dedicate each port on a thinwire MR to a single user! (Unless of course you have bucks to throw away which I doubt many of us do.) We probably average 10 hosts on a segment. Plug THAT into your numbers. And your telephone installers must be total losers if they can't handle coaxial cable at all. My installers picked it up in about 5 minutes. The designers took a bit longer, maybe 15 minutes. We've had the process integrated into the work order infrastructure for quite a while. And its nit picking but I take exception to your assertion that utp is actually cheaper to install. I can buy good thinwire for about 8 cents per foot and level 4 UTP for about 10 cents per foot. I know you don't need level 4 cable for ethernet but I wouldn't install anything else these days. I figure it costs me about $130 per workstation to do a nice job with either. EXCEPT where I DO have hosts colocated, I can do the marginal unit for next to nothing with thinwire. With UTP I have to go a whole extra cable and port OR buy one of those converter units. If you want, I'll forward a some spreadsheets done for actual network comparisons. Wow... Jeff Crowder Virginia Tech jcrowder@GroupW.cns.vt.edu ---------------------------------------------------------------------- Article 4509 of comp.dcom.lans: Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!news.iastate.edu!ceres.physics.uiowa.edu!zaphod. mps.ohio-state.edu!swrinde!elroy.jpl.nasa.gov!decwrl!fernwood!synopsys!arnold Newsgroups: comp.dcom.lans Subject: Re: 10Base-T hubs Message-ID: <721@synopsys.COM> From: arnold@synopsys.com (Arnold de Leon) Date: 13 Apr 91 04:17:14 GMT Sender: news@synopsys.com References: <1991Apr9.181721.15560@leland.Stanford.EDU> <1593@vtserf.cc.vt.edu> <1991Apr11.044735.1221@ux1.cso.uiuc.edu> Organization: Synopsys Inc. Keywords: 10Base-T Summary: more arguments for 10Base-T Lines: 56 In article <1991Apr11.044735.1221@ux1.cso.uiuc.edu> german@uxh.cso.uiuc.edu (Gregory German) writes: >Money is not the only issue here. For the most part I would claim >that it is asking for trouble to daisy-chain between offices and I >very rarely design a network that includes daisy-chains outside of >labs/classrooms. Your users are at the mercy of the guy in the next >office and everyone on that segement MUST be on the same network. >If you want to place one person on a separate network you have to >rewire. > We're in the process of moving into a new building which has 10 different subnets. UTP really wins for virtually being able to put any any office on any subnet. Our last installation was thin wire and it was exciting everytime someone rearrange their office, gee my bookcase would fit better if that little piece of cable wasn't there. It was even worse when the the network became too busy and and I had to find a way to take flat network and subnet/bridge it (It was impossible to group workstations to their servers). >I don't think anyone is really advocating pulling UTP. My main reason to >use it is to avoid having to pull cable into each office right next to >unused UTP pairs. If I have to install cable I would use thinnet, BUT >I would for the most part opt for homeruns for reliability, flexibility >and manageability. > We did pull UTP for the new installation. Aren't thin-wire ports more expensive that UTP ports on hubs? You seem to imply 1 port per user. >You have a valid point about colocated hosts being a problem with 10baseT. >The converters back to coax can work, but are in the $450 range and have >some limitations. I bought a couple of the converters for less than $300. > >My point is that there are other considerations than just cost and other >costs than just installation. IMHO there is and will continue to be a >place for both technologies. > Another thing I like about 10 base-T is the ability to monitor link status. Given the right hub you can tell if a host has been unplugged or powered down or up. You can potentially use this as a way to monitor access to your network. It would be more difficult for a user to add an unauthorized node. > Greg German (german@sonne.CSO.UIUC.EDU) (217-333-8293) -- Arnold de Leon arnold@synopsys.com Synopsys Inc. (415) 962-5051 1098 Alta Ave. Mt. View, CA 94043 ---------------------------------------------------------------------- Article 4515 of comp.dcom.lans: Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!uwm.edu!spool.mu.edu!sdd.hp.com!cs.utexas.edu!su n-barr!newstop!sun!amdahl!netcom!jbreeden From: jbreeden@netcom.COM (John Breeden) Newsgroups: comp.dcom.lans Subject: Re: 10Base-T hubs Keywords: 10Base-T Message-ID: <1991Apr13.195139.5149@netcom.COM> Date: 13 Apr 91 19:51:39 GMT References: <1593@vtserf.cc.vt.edu> <1991Apr11.044735.1221@ux1.cso.uiuc.edu> <721@synopsys.COM> Organization: Netcom - Somewhere in the S.F. Bay Area Lines: 42 In article <721@synopsys.COM> arnold@synopsys.com (Arnold de Leon) writes: > > Another thing I like about 10 base-T is the ability to >monitor link status. Given the right hub you can tell if a host >has been unplugged or powered down or up. You can potentially use this as >a way to monitor access to your network. It would be more difficult >for a user to add an unauthorized node. > I really don't think that LI by itself provides or adds any real "management" capability to 10baseT. 1. What good is it to know if a station is either unplugged OR powered down (or dead)? I need to know which it is, LI by itself doesn't tell me. 2. In terms of an "unauthorized" node on the net, it seem that refurs to an "unauthorized" mac address. Just unplug a "known" node and plug in a new device. LI won't know the difference (and LI "dis- apearing" momentarily dosn't help - LI has no way of telling WHY LI went away (see #1). 3. LI can't tell me how GOOD a connection I have, just that SOME type of connection exists. Real World: Bad TP wire run drops 10-20% of the packets sent - LI reports "all ok". LI IS a real handy function when INSTALLING wire/nodes (lets me know I have tranceiver to transceiver connectivity), but is pretty usless as a way to "manage" my network. Knowing that I don't have continuity is pretty useless until I know WHY. I've seen one MAJOR company that decided to alarm EVERY LI port to EVERY PC in their network. It lasted one day. At 5 o'clock their management system went crazy - everybody turned off their PCs and went home. -- John Robert Breeden, jbreeden@netcom.com, apple!netcom!jbreeden, ATTMAIL:!jbreeden ------------------------------------------------------------------- "The nice thing about standards is that you have so many to choose from. If you don't like any of them, you just wait for next year's model." ---------------------------------------------------------------------- Article 4539 of comp.dcom.lans: Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!uwm.edu!rpi!zaphod.mps.ohio- state.edu!mips!pacbell.com!tandem!netcom!jbreeden From: jbreeden@netcom.COM (John Breeden) Newsgroups: comp.dcom.lans Subject: Re: 10BaseT vs. Twisted Pair? Message-ID: <1991Apr16.175210.5468@netcom.COM> Date: 16 Apr 91 17:52:10 GMT References: <1991Apr8.135731.2901@eng.umd.edu> Organization: Netcom - Somewhere in the S.F. Bay Area Lines: 46 In article <1991Apr8.135731.2901@eng.umd.edu> naiming@eng.umd.edu (Naiming Shen) writes: > >I was told by a salesman that Twisted Pair scheme is different than >the 10BaseT. He said 10BaseT uses 2 pairs of wires, while Twisted Pair >uses only one pair of wires and a converter can be added to this twisted >pair so that thin net cable can be connected to the converter. It sounds >great for the Twisted Pair scheme(only one pair of wires, thin wire can >be added), I am wondoring if there is any shortcomings? > Your *salesman* needs to go back to school..... Twisted pair is WIRE and 10baseT runs on twisted pair (2 pairs rx and tx). BTW, the two pairs defined in the standard (pair 1&2 and pair 3&6) are defined as data pairs in the AT&T Premise Distribution Spec (what 10baseT's wiring is based on and also where the RJ45 comes from). The remaining two pairs are for phone or ISDN (both ISDN and PBXs use 4,5,7,8 as the two voice pairs). What your *salesman* is referring to is a twisted pair balun (3Com makes one called the PairTamer). The advantage? Real Cheep and only uses 1 pair. Disadvantage? NOT a standard (10baseT specifically outlaws baluns (passive device) and calls for repeaters - a 10baseT hub is a multiport repeater - an active device). Baluns are passive devices, prone to noise and jitter (compaired to 10baseT) and are propriatory (ie: not defined by any standards body). The *standard* PDS twisted pair wire pulled to the desktop is 4 pair twisted. What your *salesman* SHOULD have said is there are a *number* of ways to run ethernet over twisted pair, 10baseT (an IEEE standard), baluns (ala PairTamers) and propriatary protocols used before the 10baseT standards (ie: Synoptic's Lattisnet, Cabletron and David System's old protocols etc). 10baseT is installed today more than any other medium in large nets because it's a standard (ie: You can mix and match different vendors based on best price/performance/features) is more reliable (10baseT hubs jam bad ports, are active repeaters and compensate for jitter on the receive end) and is easier to manage (the many different vendor MAC level hub "management" "features" built into products). -- John Robert Breeden, jbreeden@netcom.com, apple!netcom!jbreeden, ATTMAIL:!jbreeden ------------------------------------------------------------------- "The nice thing about standards is that you have so many to choose from. If you don't like any of them, you just wait for next year's model." ---------------------------------------------------------------------- Article 4544 of comp.dcom.lans: Path: rs6000.cmp.ilstu.edu!ux1.cso.uiuc.edu!uwm.edu!cs.utexas.edu!uunet!telebit!brian From: brian@telebit.com (Brian Lloyd) Newsgroups: comp.dcom.lans Subject: Re: Avoiding the bandwagon Keywords: 10baseT thin 10base2 UTP Message-ID: <1991Apr13.003153.8136@telebit.com> Date: 13 Apr 91 00:31:53 GMT References: <1991Apr12.082529.20689@beach.csulb.edu> <20387@brahms.udel.edu> Sender: news@telebit.com Organization: Telebit Corporation; Sunnyvale, CA, USA Lines: 17 Nntp-Posting-Host: napa.telebit.com In our networks here at Telebit we mix UTP and thin ethernet as a matter of course. We use centralized 10baseT hubs for the distribution of signal to, for the want of a better term, "workgroups." At each workgroup (usally a cluster of cubicles) we use an UTP-to-thin ethernet repeater/adaptor. This way we get the isolation and ease of cabling that UTP provides, and we get the flexibility for adding or removing devices that thin ethernet provides. -- Brian Lloyd, WB6RQN Telebit Corporation Network Systems Architect 1315 Chesapeake Terrace brian@napa.telebit.com Sunnyvale, CA 94089-1100 voice (408) 745-3103 FAX (408) 734-3333 ---------------------------------------------------------------------- (*** the end ***) -- Eric Behr, Illinois State University, Mathematics Department =====> ejbehr@rs6000.cmp.ilstu.edu <=====