Several recent proposals for an “active networks” architecture advocate the placement of user-defined computation within the network as a key mechanism to enable a wide range of new applications and protocols, including reliable multicast transports, mechanisms to foil denial of service attacks, intra-network real-time signal transcoding,and so forth. This laudablegoal, however,creates a number of very difficult research problems, and although a number of pioneering research efforts in active networks have solved some of the preliminary small-scale problems, a large number of wide open problems remain. In this paper, we propose an alternative to active networks that addresses a restricted and more tractable subset of the active-networks design space. Our approach, which we (and others) call “active services”,advocatesthe placementof userdefined computation within the network as with active networks, but unlike active networks preserves all of the routing and forwarding sema...
Elan Amir, Steven McCanne, Randy H. Katz