Stanford Networking Seminar

12:15PM, Thursday November 11, 2010
Packard 202

TCP and the regulation of foraging in ant colonies

Deborah Gordon, Balaji Prabhakar
Stanford University

About the talk:
Ant colonies operate without central control and resemble large distributed systems. We explore how ant colonies use a TCP-like algorithm to solve a problem analogous to bandwidth probing in the Internet. A long-term study of the behavior and ecology of harvester ants in the Arizona desert shows how colonies regulate foraging. The ants obtain water from metabolizing the fats in the seeds they collect, but they lose water when out foraging in the sun, and also lose foraging area to neighboring colonies if they don't forage. Thus a colony must regulate *foraging rate* so as to balance the tradeoff imposed by spending water to get water; the goal is not to send out more ants than are justified by the current food supply. The rate at which a forager leaves the nest on its next trip is determined by the rate at which foragers return to the nest with food, corresponding to the 'acks' in TCP. Experiments show that ant colonies perform activities analogous to slow start, congestion avoidance, and timeouts. We will discuss our ongoing work investigating the algorithm used by ants and TCP.

About the speakers:
Deborah M Gordon is a Professor in the Department of Biology at Stanford. Her research on the collective organization of ant colonies includes studies of the long-term demography and behavior of harvester ant colonies in Arizona; the factors that determine the spread of the invasive Argentine ant in northern California; and the ecology of ant-plant mutualisms in tropical forests in Central America. She is the author of two books, Ants at Work (2000) and Ant Encounters:Interaction Networks and Colony Behavior (2010). She has been awarded fellowships from Guggenheim and the Center for Advanced Study in Behavioral Sciences. She is interested in analogies between ant colonies and other distributed networks, and has given talks at TED, Xerox Park, Google Tech, Dagstuhl seminar on distributed algorithms, and at robotics and artificial intelligence conferences.

Balaji Prabhakar is a faculty member in the Departments of Electrical Engineering and Computer Science at Stanford University. His research interests are in computer networks; notably, in designing algorithms for the Internet and for Data Centers. He has helped develop the IEEE 802.1Qau standard for an Ethernet congestion management scheme, called QCN. Recently, he has been interested in Societal Networks, such as transportation networks, electricity grids, healthcare systems and recycling systems. He has been involved in developing and deploying incentive mechanisms to move commuters to off-peak times so that congestion, fuel and pollution costs are reduced. He has been a Terman Fellow at Stanford University and a Fellow of the Alfred P. Sloan Foundation. He has received the CAREER award from the U.S. National Science Foundation, the Erlang Prize, the Rollo Davidson Prize, and delivered the Lunteren Lectures. He is a co-recipient of several best paper awards.