Clack: an active network platform

We have designed and built an active networking platform that adds active processing capabilities to the Click modular router (Kobler, E. et al., ACM Trans. on Computer Systems, 2000). The Clack platform comprises an active element for Click, a minimal set of libraries to provide interaction between protocols and end user applications, and a daemon process to handle active communications on end hosts. Many recent developments in active networking are restricted in that core router functions cannot be easily changed for experimentation or for adaptation to a particular situation. In the spirit of Click´s fine grained modular approach, the Clack element is also divided into interchangeable components to allow, for example, the addition of new execution environments or protocol fetching rules. Our platform concurrently allows the use of multiple execution environments supported by the router´s base operating system.