Network Computingwww.networkcomputing.com

With a couple of billion dollars' worth of equipment at their feet (literally), it didn't take long for the network operations control (NOC) team to pinpoint that one. Never saw a problem an unlimited budget couldn't solve. And, our thanks to Mike Pennacchi for relaying the following horror story to us:

"A user was complaining about his PC locking up at least once a day. The network driver software had been upgraded, the NIC replaced and the operating system reloaded--all to no avail. Upon closer inspection, I found a piece of telephone wire coming out of the wall into a big old ugly ball of black electrical tape. Out of the other side of the electrical tape was a section of Category 5 cable.

"After rewiring to a new RJ-45 jack, I cut the old cable and began dismantling the tape ball. Inside, someone had soldered wires from the telephone cable to the CAT 5 cable. Only two of the CAT 5 wires had electrical tape around them, so every time someone stepped on the connection, the wires would short. As far as I know, this PC has not locked up since the move to the new jack."

Scott: Sounds like you had a ball with that one.

Bill: Which reminds me of the cons truction worker who accidentally severed a fiber optic link. When part of the network went down, it was traced t o that link.

Scott: And what do you suppose the network engineers discovered?

Bill: The severed connection had been put back together--with a twist-on electrical wiring nut securely wrapped with electrical tape.

Scott: Next, we thank Al Deshotel for this story:

"The computer operator paged me at midnight and asked, 'How do you restart the VAX?' Naturally, I asked why, and he told me that there was a power failure. The machine was on a large UPS, so I knew there was no way it could have just lost power.

"It turned out that the regularly scheduled power generator test at midnight had occurred--as planned. The UPS tripped off and went onto backup power while the generator was spinning--as planned. When the UPS started beeping because it was running on battery, our new computer operator thought something was wrong and turned it off!"

Bill: Ugh. And those VAXes don't exactly boot up in 60 seconds.

Scott: Think your network is hot? Check out this story from Jon Wyrick:

"A few years ago, I received a call from a gentleman who asked me to come and have a look at his Ethernet network. It seems that the network was having some strange problems, and every day around noon it would go down for no apparent reason. Armed with my cable tester and other goodies, on this dismally overcast summer day, I arrived on site and began checking out the wiring (10BASE-2 with RJ-58 coax) for proper distance, impedance, termination, etc. After failing to find a cause, and not having the network fail, I called it a day.

"The following day was bright and sunny, and I started my hunt once again. After a quick cable check, I decided to try new terminators on the ends just in case they were flaky. On my way to locate one of the cable ends, I happened to overhear someone say, 'It's doing it again.' This person als o happened to have a PC at the end of the coax, where one of the terminators was located. I reached behind the machine to undo the terminator and nearly burned my fingers because the terminator was so hot! I replaced it, and the network came back. It turns out that the terminator was up against a window where the hot sun was baking it, causing it to lose its 50-ohm resistance and break the network. I moved the computer away from the window and the problem disappeared."

Bill: We'll end this year's horror stories with this mystery from Ronald Dupas, who tells us about the Friday the 13th, er, 22nd problem:

"One day, our accounting clerk reported that one of the monthly financial reports was dropping data. Upon inspection of the report, I noticed that the last data printed every time a loss occurred was '22-JUN.' So you'd have 22-JUN and then the columns of print were offset until things seemed to reset and print would continue normallyÉ until 22-JUN was encountere d again. This happened on any printer receiving data over the network.

"Next, terminal users began to notice that response time was extremely slow. I noted that if I scrolled the same print file on a terminal, whenever 22-JUN showed up, the terminal 'froze' for a few seconds, and then continued scrolling. Then I found out I couldn't transfer files over the network if they had 22-JUN in them!

"I borrowed a network analyzer and began watching packets. Whenever 22-JUN showed up in the data display, packet errors were generated. Finally, I determined that the problem only occurred as users began working in the morning. Suspecting a PC, I began disconnecting PCs from the network one at a time until I hit one that functioned like an on/off switch for the problem.

"I now had a predictable, repeatable event. Replacing the NIC in this one PC solved the problem. To this day, I've never been able to find anyone who could tell me why the particular bit pattern '22-JUN' was there and disrupting packets--the PC must have been generating this bit-pattern at random intervals on the cable."

Scott: That's scary stuff.

Bill: Proving once again that you never can tell what's lurking On the Wire.

Bill and Scott can be reached at otw@pmg.com. Portions of trace files from selected columns are available via Pine Mountain Group's Home Page (www.pmg.com).