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Please do not scare the pigeons – they'll crash the network

Sysadmin outsmarts rats with wings, but they manage to have the final turd

By Simon Sharwood, 9 Jun 2017

On-Call Welcome again to On-Call, The Register's Friday column in which we share readers' recollections of odd jobs in odd places at odd times.

This week, meet “Ethan” who tells us that “in the heady days of the 1990s I was employed as an IT engineer at a company providing booking systems to entertainment venues around the UK.”

Ethan says the job mostly involved “driving around the country and plugging cables back in that had spontaneously become disconnected and often evaporated completely”, evaporation being Ethan's best guess about the cause of problems in situations when users would not admit to having touched a thing.

One day he came across something even odder. To set the scene, Ethan told us this took place “in the days of 10BASE2 cheapernet cabling that was hung around the office like a string of Christmas lights. For those not old enough to remember, the major disadvantage of this type of cabling is that a single break anywhere would bring down the entire network.”

The problem on this site was that the network would go down just as punters filed into venues to pick up their tickets before a show. When the production started, Ethan says “the network would miraculously come back up again.”

So Ethan was “dispatched to drive four hours each way across the country (with a vague promise of lieu time) to fix the problem.”

Upon arrival he quickly observed that the problem was real: just as the first theatregoers arrived for the evening performance the network fell over. So Ethan grabbed his trusty cable tester and started to follow the wires through the theatre.

“I eventually found a cable exiting the building through a hole in the wall. Tracing it, I found that it left the building and continued to an outdoor box office kiosk suspended by a wire support about three meters above the ground.”

“However, as soon as I went to the little used external box office, the network came up again. I returned to the main building and tested again – the network was down. I repeated this several times and found that the same thing occurred… as soon as I left to look at the outbuilding, the network was up and when I went inside, down it would go.”

“It took a while but I eventually discovered the cause. When the general public arrived for the start of the show, they would disturb the pigeons pecking around outside the building which would immediately fly up and sit on the same wire supporting the network cable. If three or more pigeons sat there, their weight was enough to stress the cable enough to cause a break in one of the connectors.”

But if Ethan appeared to look at the cable, the pigeons would fly off and the network would revive.

The fix was simple: Ethan re-crimped the cable, which made it strong enough to endure a little more weight.

But the pigeons took revenge: he got back to his car to find “the birds had had the last laugh and carpet bombed my car with their special presents.”

Have you found a weirder source for a problem than Ethan's birds? If so, write to let me know and it might be you who appears in On-Call next week! ®

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