TOWARDS PROGRAMMABLE NETWORKS

Intermediate nodes (e.g., routers, switches) of cur rent networks, in contrast with end nodes (e.g., PC s workstations), are vertically integrated closed sys tems. Their functions, mostly implemented by embedd ed software, are rigidly built-in by intermediate node s vendors. Vendors must follow designs dictated by slow and intractable standard committees rather tha n pursue rapid introduction of innovative costeffective technologies. There is thus a need for ne w technologies that would enable programming intermediate nodes with the same simplicity of programmi ng end-nodes. This paper describes the NetScript project, pursuing agent-based middleware for progra mming functions of intermediate network nodes. Delegated agents are used to deploy functions in in termediate nodes. The NetScript programming language provides means to script processing of packet streams; it is particularly suitable to program ro uting, packet analyzers or signalling functions. This pap er describes an architecture for programmable netwo rk nodes; middleware for agent-based programming of th ese nodes; the NetScript language to program node functions and applications of these technologies to create programmable SNMP agents, protocol analyzers, signalling and routing protocols and firewalls.