Geoffrey S. Mendelson wrote on 2003-07-24: > Beni Cherniavsky wrote: > > > > My home network consists of 3-4 computers and an ADSL modem all > > connected one to the other with cross RJ45 cables, with no hubs. > > This was simplest at each point in time (it started with two computers > > and one cable and at each point I had enough network cards) but it's > > somewhat inconvenient because intermediate computers sometimes need to > > be up just to pass the packets. > > You could also do it wit some routing tables, for example, I assume that > you have network segment on a different subnet (shame on you if you didn't): > > computer 1: > 192.168.1.1 > > computer 2 > 192.168.1.2 crossed to computer a 192.168.1.1 > 192.168.2.2 crossed to computer c 192.168.2.3 > > computer 3 > 192.168.2.3 crossed to computer a 192.168.2.2 > 192.168.3.3 crossed to computer c 192.168.4.3 > > computer 4 > 192.168.3.4 crossed to computer a 192.168.3.3 > 10.0.1.1. connected to aDSL modem. > xx.xx.xx.xx ppp conection to isp. > > This could easily be accomdated with routing, > You have guessed my setup almost precisely (the ADSL modem is connected to computer 3 and the network numbers slightly differ)! I already do it with routing but that means that computers 2 & 3 need to be up for 1 to access the net even if I don't use 2 & 3 at the moment (similar issues for some other usage cases). That's why I want hubs.
Actualy the main issue is computer 3 which holds the connection to the ADSL modem now; I rarely use this computer but I frequenltly use the net so it's up most of the day. I'd like to put a hub in front of the modem so I can bypass this computer. I guess there would be complications with ppp connections - only one of the computers can open it, so I would either designate a more useful computer (2) as the main connector or setup the net so that any computer that went up first can masquarade for the rest... > > So now I consider adding one or two hubs. But hubs need cables that > > are not crossed. Replacing all cables would cost a non-negligeble > > price. Besides one long cable passes inside the wall and replacing it > > is out of the question. I can re-solder all cables (or re-frob the > > connectors but I don't have the device that does it) but I'd rather > > avoid the trouble. > > It would be easier to get a short cable and a "punch down" wall jack > and make a 1 meter adaptor cable as needed. Cost about 50 NIS each. > Not following you precisely but with Gilad's post the needed cables count reduced to 2 and I just found a spare straight cable so I can get the 1 missing cable for even less. > > What's most annoying me about the idea is that I can see no technical > > reason for it. Why should non-crossed cables exist at all? Why can't > > the hubs have connector layout like in computers, so that > > computer<->hub cables would be crossed too and put an end to the > > confusion? What do I miss? > Nobody addressed my "rant" point - is there any reason except market inertia not to make all cables crossed? I'm not in position to change anything here but I want to know whether it's stupid or not ;-). > Some HP switches do autodetect. However every hub I have ever seen had > one port that had a a normal/reverse switch. That would cover the hidden > wire. The others could just be replaced. > > > Note that if you look at the plug with the wire in the back and the tab > on top pins are numbered 1 to 8 from the left. A normal cable has 8 wires > (4 twisted pairs) but only two pairs are used. > > They are pin 1 and 2 pair one, pin 3 and 6 pair two.Reveresed cables > have one side the same, the other with pair twon on 1 and 2 and pair two > on 3 and 6. Wires on pins 4,5,7,8 are not used and can be cut. > Thanks for the details. > Are you ever in Jerusalem? If you are I can lend you the tool and I'll > give you a handful of plugs, or you can get them sometimes at home center > or Kashayoff on King George. > No, I'm near Haifa... > > I recall that some new cards "autodetect polarity". Does this refer > > to polarity on each pair or also to Tx/Rx autodetection? Is there a > > chance that it will work with crossed cables anyway? Is it safe to > > experiment of do I risk letting the smoke out? > > Never had a problem doing so, but that does not say that ALL cards > are safe to experiement. > I'll risk it. -- Beni Cherniavsky <[EMAIL PROTECTED]> If I don't hack on it, who will? And if I don't GPL it, what am I? And if it itches, why not now? [With apologies to Hillel ;] ================================================================= To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
