When animals attack

Networks pay the tab for voracious varmints.

The crime scenes last February in rural Sweden looked remarkably similar despite being 90 miles apart. The perpetrators appeared to have entered through the smallest of cracks. Footprints dotted the snow. Each case claimed more than a thousand victims.

And then, there were the telltale teeth marks.

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No doubt about it: Field mice had done the dirty deeds.

TeliaSonera, a Stockholm telecom carrier, suffered two nearly daylong network outages that caused roughly 4,000 wireline and wireless customers' phones to go quiet as, well, the mice. The company squarely laid the blame at the tiny paws of rodents that the Swedes call sorks.

The outages were maddening in that they were caused by the animals gnawing through fiber-optic cables after shimmying through 2-centimeter-wide gaps between cement valves and locks designed to protect the phone lines from animals and forces of nature, says Arne Duvberg, chief technician at Flextronics Network Services, a company that maintains TeliaSonera's networks in the region.

And don't even get him started on birds.

"We have to send out service men on a daily basis to take care of the damage being made by the woodpeckers," he says.

TeliaSonera by far wasn't the first network operator to get caught in a mousetrap and won't be the last. Just how common animal attacks on networks are, though, is hard to pinpoint. One estimate, cited by author Robert Sullivan in his 2004 book "Rats" (in which he monitors a New York City alley for a year), is that 18% of all phone-cable disruptions are caused by rats. But others say the frequency of animal-related damage is much lower. AT&T, for example, figures less than 1% of all its outages are caused by rodents.

Despite the shortage of statistics, anecdotal evidence of nature vs. network run-ins abounds:

  • In the past few years, rats have been blamed for chewing through fiber-optic cables in locations as varied as Ontario and India, leaving hundreds of thousands of customers without Internet or phone service.

  • A data center at Stanford University in the mid-1990s switched to back-up generators after a squirrel blew out the main transformer. The rodent's charred remains were found hours later, exposed by its pungent odor.

  • Texas Tech University researchers have cited red, imported fire ants as being network troublemakers as far back as 1939, when Southwestern Bell Telephone reported problems in Galveston, Texas.

  • AT&T and other telecom companies and equipment makers seeking ways to protect their networks and products from pocket gophers' choppers drew fire from animal rights activists in the mid-1990s for paying U.S. government researchers over two-plus decades to trap the animals, cage them and watch them gnaw on cables strung within the cages. Such cable-durability tests have since been halted.

  • Owners of underwater cables have had to make their links shark resistant after suffering outages caused by fish bites.

Rodents are considered especially threatening to network cabling.

"Rodents and wire damage go hand in hand," says Bobby Corrigan, a pest control expert in Indiana who calls himself an urban rodentologist.

And it's not that the animals are bent on having a high fiber-optic diet, either. Eric Spinner, pest control operator for Maven Pest Management in New Hyde Park, N.Y., explains that rodents gnaw on wires and other chewable objects to grind down their incisors.

"Failure to do so will allow them to grow long and actually occlude their lower jaws to the point where they can't open their mouths to eat," he says.

Keeping critters at bay

Methods for animal-proofing your network, according to pest control experts:
Protect cabling in metal sheating or PVC ducts.
Minimize food in data centers. Even though many data centers are physically secured, some rodents only need a pencil-size hole to sneak in.
Keep outside cabling away from spots where animals can climb or jump.
Avoid gizmos, such as ultrasonic machines.
Avoid gizmos, such as ultrasonic machines.

Telcordia, which crafts specifications used by carriers and equipment makers, tests for the hardness of cables and equipment enclosures, and recommends cabling be protected in covering with at least a 1- or 2-inch radius to prevent certain animals from wrapping their jaws around it.

Ernie Gallo, director of telecom services at Telcordia, says the increased use of fiber-optic cabling has forced carriers to pay more attention to network protection, given that the outage of a single fiber connection can mean many more businesses and individuals will be affected than they will when they are old copper links go down.

Protecting networks from animals isn't only about keeping up communications links. It's also about safeguarding field technicians who work on the lines. Requirements are followed in designing equipment enclosures that are meant to keep insects such as wasps from building nests within them, Gallo says.

Efforts such as covering cables with pepper spray have been made over the years to discourage cable-chewing, Gallo says. Although he emphasizes that sticking to the basic Telcordia specifications can greatly reduce, if not eliminate, animal interference.

Jay Adelson, CTO and co-founder of Equinix, a provider of data centers and Internet exchange services, says a massive rodent-eradication program is one of the first things his company does when building a data center.

"We make sure we quarantine off the building with steel walls and find any point of entry and seal it up," he says.

While outside cabling is commonly sheathed in metal to avoid animal or other damage, armoring cable within a data center can greatly limit the flexibility of cable that might need to be moved often, he cautions. Cabling company experts also say that armoring wires can as much as double the cost, so careful risk vs. cost assessments must be done.

Stuart Aust, for 15 years the owner of Bug Doctor in Paramus, N.J., says his company has helped to protect enterprise networks by putting bait stations outfitted with "rodentcide" under raised floors in computer rooms. "We provide a deodorizer as well," he says, for those cases where rodents die and aren't discovered right away.

Of course, even the best efforts to animal-proof networks aren't always successful.

"Data centers might seem secure, but if there is any hole - if you can put a pencil through it - then a mouse can get through it," says Greg Baumann, technical director for the National Pest Management Association.

Data centers generally provide three things rodents need: food, water and safe harbor. "While companies might not encourage bringing food into these climate-controlled spaces, there is always the leftover birthday cake or emergency granola bars," he says.

And once critters get into a data center, even armoring cable will not necessarily stop them from damaging wires or getting into electrical systems that power networks, says Steven Elmore, an applications engineer with cable maker CommScope.

"It will just slow them down," he says. "I've actually seen armored cable chewed through."

New animal control methods are always in the works, says Michael Conover, director of the Berryman Institute, a national organization focused on resolving human-wildlife conflicts.

"We have been doing research on impregnating a rodent repellent into the plastic covering of cables," he says. "While this approach works in the short-term, it is too early to tell if it is a long-term solution."

You might think the shift from wire-based to wireless networks might give animals less to chew on going forward, but that's not necessarily the case. "There are still a lot of wires in wireless networks," CommScope's Elmore says.

Meanwhile, network professionals say it actually isn't the rats, ants and gophers that have them most concerned. When Flextronics' Duvberg was asked to point out the most harmful animal he answers quickly: "Homo sapiens. When an excavator causes problems, one thing is for sure: The problems are big."

Bostrom is a reporter with IDG News Service in Sweden.

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