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Newsgroups: bit.listserv.novell
Date:         Fri, 2 Oct 1992 19:15:39 -0600
Reply-To:     Novell LAN Interest Group <NOVELL@SUVM.BITNET>
From:         Joe Doupnik <JRD@USU.BITNET>
Subject:      Re: "Server Not Found" problems

>
>Hope this isn't too long, but I'm at wits end.
>
>We've been having a very frustrating series of "server not found"
>errors on our machines as they attempt to boot from boot ROMS on
>the cards.
>
>Initially the problem occurred occasionally in random machines,
>and frequently on one machine.  We replaced the card on the one
>machine, and it behaved fine.  Then (on a weekend, of course,
>just as a class of 20 students was sitting down to simultaneously
>use the machines and while I was at home) all hell broke loose.
>About ten of the machines refused to boot, giving the "server not
>found" error.  Grrr.  Class cancelled.
>
>The plot thickens a bit here.  When I returned on Monday I was
>getting quite a few "server not found" errors on many machines.
>I also noted that power had gone out over the weekend, the night
>before the.  However, it was only out for 10 seconds, and,
>according to the system error log our BACK-UPS UPS kicked in and
>the server never shut down.
        <plot involutions deleted>
>For some reason (at least until we noticed that the power was out
>in both situations), we suspected cable problems -- though this
>would be odd, since machines "downstream" from the ones unable to
>find the server were booting just fine.  Some history here:
>
>We decided to go with pre-cut cables to increase reliability,
>since I had heard all kinds of weird stories about cable problems
>when people "rolled their own."  Come to find out, however, that
>that the company we bought them from used twist-on, not crimp-on
>cables.  We could have done that ourselves.  These people also
>insisted on making no cable shorter than 5 feet (they said that
>shorter lengths would be unreliable, though Novell specifies a
>minimum length of 1.5' in the docs).

        I'd suspect the coax quality too if they did all this.

>We checked the resistance of the cabling with a VOM today  (leads
>attached to center and shell one "direction" at a time...).  It
>was around 50-70 everywhere.  Averaged around 57 or so. It seemed
>to increase by a couple of ohms each cable length.  This seems
>like more resistance that I'd expect in a 5-foot length.  I'm no
>whiz with a VOM and the digital display seemed to move around
>quite a bit.  Is this pretty close to spec or way off?

        Not very close. You should be seeing close to 25 ohms plus
cable resistance, say upwards of 28 ohms. Signals on the wire make
this a difficult measurement until a few idle seconds occur. Even
if you removed one terminator and looked into the cable from there
57 ohms is a mite high.
        Other VOM folklore: try reversing the red/black wires too,
looking for d.c. on the wire. Some boards go bad and leak to the
coax and thus bias signals on d.c. coupled boards elsewhere.
        If those twist-ons are still present you should remove them
forthwith. Oxidation will destroy their meger electrical contacts. Full
crimp connectors, Mil Spec items, are the solid kinds. Give the twist-ons
to your worst enemy.
        Relaying a similar experience from here this week. Twisted
wire in a lab. Unreliable logons, some stations were ok, others not.
Two problems: had to recrimp some RJ45s (oxidation and small mechanical
stresses worked loose a wire or two), and more importantly, room vacuuming
had upset the multiport repeaters ("hubs" to twisted pair people) and those
needed resetting by power off/on again. Flakey power can cause the internal
electronics to go into odd states.

>My current conclusion is that the network gets lonely if I don't
>log in with my username, and refuses to boot any workstations.
        More than likely, close to the truth. Our experience is servers
hear us coming and snap to attention.
        Joe D.
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