Wireless Meets Mother Nature
It’s important to remember that the answer’s not always in a book or taught in a class, as we found out when investigating a disrupted wireless link.
In a former job as a PC technician in Norman, Oklahoma, I
didn’t get a lot of hands-on experience with networking. I’d been there
about a year and a half and was getting very familiar with our predominantly
Novell/Windows NT network. We were using drive mappings for several of
our major network applications. We had a handful of offsite doctor clinics
we supported through the hospital.
I was responsible for all offsite facilities, which wasn’t a bad gig:
It got me out of the office, away from the boss, and trips were usually
short and sweet. One morning a call came in that an offsite location had
entirely lost connectivity. This particular site, as well as several others,
had a wireless WAN link that stretched a couple of miles across town.
The site’s two-story building was square, perfect for mounting an antenna
By the time I arrived, the whole system was up and running normally.
The users told me they didn’t know what happened; they kept trying to
log in, and the network finally let them.
It appeared to be a fluke; I’ve seen them before. But then it happened
again, and the problem repeated itself. I made five or six trips back
and forth that day, and practically every day for several weeks, each
time for the same connectivity problem. It was hard to tell if I ever
fixed it, because some days I wouldn’t hear from them and the next day
I would. Finally, I started asking colleagues to come and prove I wasn’t
We checked everything inside and out, but found nothing. Finally, we
plugged a laptop into the switch at the offsite location, ran a continuous
packet count using PING with TCP/IP and let it run for several minutes.
It would send and receive packets at 100 percent, then all of a sudden
it would drop everything. If we waited, though, it would jump back up
and work like a champ.
We spent several days lining up our antenna with the marks we’d tested
and made to line up across town at the hospital. One frustrating afternoon,
as the network administrator and I stood on the roof of the building scratching
our heads over this puzzle, he decided to lay his face down on the antenna
and look down it like the barrel of a gun.
Between the branch office and the hospital is a beautiful golf course,
which the network admin and I had played several times together. One thing
that makes this course so nice (and evil in some cases) is that it has
several large trees. As we looked down the barrel of the antenna, we noticed
a tree growing in the path of the hospital and the site’s antenna a mile
or two away from us.
Further investigation revealed that the tree had grown just inside the
wireless transmission path from the time the antenna had been placed;
once its leaves blossomed, the tree started blocking our transmissions.
The kicker is that it wasn’t always in the way; a strong wind—a nearly
everyday occurrence in Oklahoma’s spring and summer—would push the tree
in the way and block the transmission.
We discussed the proper time that evening to jump the fence with a chainsaw
and cut that tree down. Eventually, though, we came to our senses and
decided that we should just raise the antenna another ten feet. How long
that will work I don’t know, but I do know that’ll be the first thing
checked the next time there is a rash of disconnects.
It’s important to remember that the answer’s not always in a book or
taught in a class. So often I meet “certified technicians” that haven’t
learned to think outside the box. That’s a valuable lesson.
Justin L. Melot, MCP, A+, is a systems specialist II for Unity Health Center in Shawnee, Oklahoma. He started working on medical information systems in 1998 at Norman Regional Hospital in Norman, Oklahoma.