Date: Fri, 4 Aug 2000 11:40:18 -0700 (PDT) From: "Rodney W. Grimes" <freebsd@gndrsh.dnsmgr.net> To: oberman@es.net (Kevin Oberman) Cc: behanna@zbzoom.net, arap@oduurl.ru (Alexander), strbenjr@yahoo.com (Ben Hacker Jr), fug-washdc@Sytex.Net (list DC-FBSD), freebsd-questions@FreeBSD.ORG (questions FBSD), freebsd-stable@FreeBSD.ORG (Stable FBSD), bhacker1@csc.com (Ben Hacker Jr) Subject: Re: Router "ep2" issue Message-ID: <200008041840.LAA80077@gndrsh.dnsmgr.net> In-Reply-To: <200008041542.e74FgsU32161@ptavv.es.net> from Kevin Oberman at "Aug 4, 2000 08:42:54 am"
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> > Do these problems happen during thunderstorms, perchance? > > > > One of my coworkers recently turned me on to the fact that the > > ethernet standard requires that the NICs, and all components of the > > network, be properly grounded (no, not just to the box chassis) to be > > reliable. Of course, no one really does this, and most of the time > > you can get away without it, but sometimes you can't. > > Could provide a citation for this. I can't find this anywhere in my > copy of 802.3. Of course, it's a rather thick document and I could > have missed something, but grounding is something that Ethernet was > deliberately designed to NOT require. I don't think you'll find this in 802.3, but perhaps in TIA-565 or TIA-606. The unused pairs in CAT-5 cables should be AC grounded to telco/chassis ground to minimize crosstalk, RFI/EMI and EMP reception/ transmission. If you look on most NIC cards you'll see that the unused pairs are hook through 47pF (or there about) to ground. > The spec does call for medium grounding for 10Base5 and allows for it > (but does not require it) for 10Base2, but that's about it. Anyone running Coax of any real length is a fool not to have it properly gounded. Without the ground it is one big antenna, and in a lightning storm the EMP wave can induce 100's to 1000's of volts on a long piece of ungrounded coax, especially something as large as 10Base5. -- Rod Grimes - KD7CAX @ CN85sl - (RWG25) rgrimes@gndrsh.dnsmgr.net To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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