Research in Active Networks can be broadly divided into two distinct camps. The first is the integrated or in-band approach and the other is the discrete or out-of-bound approach.

Integrated approach: Here, lightweight datagrams are replaced by capsules that contain both the program to be executed in the network as well as the data. These capsules are executed on the nodes as they pass through.

Discrete approach: Here, functionality is added to the node separately making them capable of processing the packets that flow through them.

MIT is working on ANTS (capsule approach) where functionality is added to the nodes by an implicit code distribution scheme. If a node does not have the necessary capabilities required to process a capsule it uses demand loading to obtain the required code from the previous node traversed followed by caching for reusability of the code by subsequent packets. The architecture of this system allows new protocols to be dynamically deployed at both routers and end systems, without the need for coordination and without unwanted interaction between co-existing protocols.

U.Penn and Bell Communications are developing a programmable switch (discrete approach) in which the IP packets are separated into two distinct types. Users could first send a program to extend the functionality of the nodes and then inject data-packets that use this extended capability. The node treats the two types of datagrams separately.

The NetScript project (discrete) consists of a programming language and execution environment. The language provides a means to script the processing of packet streams. Here agents set up packet dataflow structures and allocate resources. It is particularly suited to the implementation of routing, packet analysis, signaling and management functions. NetScript agents can be sent to remote systems including intermediate network nodes, such as routers and switches. The goal is to enable programming of these nodes as easily and quickly as end­systems.

The BBN Smart Packets project (integrated) approach is similar to ANTS, the difference being that here the packets are kept lightweight but still express their requirement. It focuses on network management applications looking more deeply into security requirements.