Xref: utzoo comp.dcom.lans:1453 comp.protocols.tcp-ip:3780 Path: utzoo!attcan!uunet!yale!cmcl2!phri!roy From: roy@phri.UUCP (Roy Smith) Newsgroups: comp.dcom.lans,comp.protocols.tcp-ip Subject: Re: Looking for comments on the 15-pin ethernet connector Summary: It sucks! Message-ID: <3352@phri.UUCP> Date: 14 Jun 88 15:28:03 GMT References: <5047@videovax.Tek.COM> Reply-To: roy@phri.UUCP (Roy Smith) Organization: Public Health Research Inst. (NY, NY) Lines: 58 dmc@videovax.Tek.COM (Donald M. Craig) writes: > I am looking for feedback on the quality and reliability of > the slide latch mechanism used on the DB-15 ethernet connectors. In a nutshell, they suck! There is no doubt that the single most common cause of problems in our entire network (19 Suns, a Vax, and maybe a dozen Macintoshes and PCs) is loose ethernet tranciever cables, particularly on the backs of Sun-3/50's which provide no mechanical support for the cable at all. On our rack-mount systems, we support the cables with cable ties to various convenient supports. On our deskside suns, we've constructed assorted mechanical strain reliefs. Some of our 3/50's seem to be OK with just wedging the cable behind a desk but some are a constant cause of trouble. For the worse ones, we install a support bracked we've designed which helps a little (it's just a plexiglass bar notched to fit on the card extractor ears and with cutouts for the various cables and attachment points for cable ties in the appropriate places). > "I am the Component Engineer for connectors at Sun. In regards to your > question concerning the Ethernet DB-15 [...] I am not aware of any > significant problems with mechanical integrity of the lock, or for that > matter with the connector in any aspect. I'm not given to public flamage, but this guy must have his head firmly wedged in a dark place. If he's not aware of any problems, it because he hasn't been listening. I've complained loudly about this on the net before. I've complained to Sun field service. I've complained to Sun tech support. Clearly those complaints havn't gotten back to the right people. The stupid little stamped sheet metal clips are simply not strong enough to secure a connector with a big fat, heavy, and fairly stiff tranciever cable on it. As long as the cable is secured so if can't move if accidentally moved, it's OK. For example, on the tranciever ends, we lash the cable to the main ethernet trunk cable with 2 (or sometimes 3) wire ties a few inches away. But on systems which might move a little (like a deskside Sun on wheels), or in situations where the cable might be disturbed (like hanging off the back of a desk) forget it. What was wrong with good-old RS-232-style screws? Or, if they really wanted a tool-less installation, why not Macintosh-style knurled screws, or maybe even centronics-style wire bails? We recently got a 3-Com 3C503 ethernet card for an IBM-PC. The connector is a bit different, with screw holes instead of binding posts. Unfortunately, to use the screw holes you need a special adaptor bracket which I havn't been able to locate yet (OK, we just got the thing; I havn't had a chance to look very hard). It looks like it might be a bit more secure. Our Interlan ethernet board for the vax has a slight variation on the slide connector which looks like it might be marginally stronger (it has small extra ridges along the sides), but I doubt it would still be strong enough if we weren't able to lash the cable to various places in the vax's rack frame. I really don't know what the DIX guys had in mind when they designed this connector. Administering a network is hard enough without having to worry about which $5 connector is falling out. -- Roy Smith, System Administrator Public Health Research Institute 455 First Avenue, New York, NY 10016 {allegra,philabs,cmcl2,rutgers}!phri!roy -or- phri!roy@uunet.uu.net