Active networking is motivated by the notion that the improvement and evolution of current networking software is greatly hindered by slow and expensive standardization processes. Active networking tries to facilitate changes to the networking software by developing an architecture that, by design, allows safe and efficient dynamic reconfiguration of the network.
Anetd listens on a unique UDP port (e.g., the active networks port 3322) and accepts commands to download, configure and manage networking software. In addition to processing commands directed to itself, Anetd looks at the packets it receives and, if a packet is destined to one of the services it downloaded, it forwards that packet to the appropriate service. This kind of functionality is very useful in cases where several network services need to share a limited set of port numbers (as in the current architecture of an active node) and it is not possible or desirable to modify the lower level-protocols.
[Here we should put a drawing showing how the demultiplexing works]