Barging ants solve network congestion

Data packets are just too polite

Ants could help to manage the flow of data through networks, according to researchers at Université Paul Sabatier in Toulouse, France.

Vincent Fourcassié and his team studied how ants manage to avoid banging into each other on foraging trails. They discovered a pragmatic approach: faced with a blockage, an ant will simply barge the other out of the way, forcing it to take an alternative route.

Ants will lay down scent cues for their colleagues to follow when out looking for food. These trails mark the path between food and home and are reinforced as more ants use them. This makes them even more attractive, and even more ants want to use the trails.

Too many ants trying to use one route will slow the delivery of food to the nest. In his paper, published in Nature, Fourcassié reports that ants will just shove each other off the main thoroughfares, and onto chemical back streets.

Computer scientists at University College London say this simple approach could help reduce congestion in large networks – like telephone systems.

Fourcassié and team set up a trial with bog-standard garden ants. Luring them out into the open with a sugar source, the team funnelled the ants over a bridge, divided into two branches of equal width.

When there was plenty of space, on a 10mm-wide route, the ants mainly stayed on one, well-marked trail. When the branches were narrowed to just 6mm, the traffic was more evenly distributed.

Fourcassié argues that this demonstrates that outward bound ants were hitting traffic head-on. "It was not the result we expected," he says. "We expected the ants to do a U-turn and come back to the nest. But the ants found a better solution to the problem."

This helps maintain an even flow of food into the nest. Fourcassié suspects that a similar strategy is used inside the nest.

The original paper is available here, to Nature subscribers. Everyone else can read the abstract. ®

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