HEATH ROBINSON'S NETWORK INSTALLATION PROJECT

 

 

 

 

 

 

 

 

Heath Robinson's Network Installation Project

 

 

 

 

 

 

 

 

 

 

 

 

Heath Robinson's Network Installation Project

Active networks are a relatively new paradigm in which computation is moved into the network layer. In an active network as a packet flows from switch to switch it can have code associated with it executed on the switches, and this execution can change the contents of the packet, allowing the packet to meet changing needs. Packets can still carry data payloads to a destination, but they can do it with more flexibility.

Packets can also interrogate nodes on the network as they get passed from switch to switch, and thereby collect and make use of information that is hard to use effectively in a conventional (data transport, fixed-protocol network). Active networks provide solutions to several problems of more traditional networks. Current major networks, particularly the internet, have great difficulty deploying new protocols that may be more efficient, or provide greater features than currently used; they are slow to adapt to new technologies; and they have multiple levels of redundancy over several protocol layers leading to inefficiencies.

Active networks can potentially be very adaptable and extensible, while still providing core services and backward compatibility. Active networks also provide a new range of potential services, not able to be offered in conventional networks. By having memory available at switches, in the form of soft state, new classes of distributed programs can exist in the network.

Architecture

PANTS is an active networking architecture, inspired by the ANTS toolkit developed at MIT [32]. The PANTS architecture [14, 15] however, presents a much more dynamic approach to active networking. Figure 1a shows a simplified model of a traditional network node. Typically as data packets arrive at a node, preset protocols within the node operating system examine the data (usually just the headers) and process the packet according to the protocol.

This may in simple routing protocols like IP be to simply forward the packet on towards its destination, or to pass the packet up in the protocol stack for further processing. In a traditional active network (Figure 1b), the processing of the packet is not fixed to a set number of protocols defined at a node. The data arriving at a node can contain code along with its payload, thus optionally defining its own protocol.

Most current architectures split an active node into 2 separate entities - the Node OS and an execution environment. The Node OS is responsible for maintaining and managing the resources at the node. The execution environment is responsible for the execution of the mobile code arriving at the node. The execution semantics of the environment varies with differing active architectures. Most architectures also make available a library of routines (services) that may be invoked from the execution environment. These services can be to access node resources, or widely used/needed routines.

It should be noted that some newer architectures allow services to be upgraded/installed dynamically without taking the node down. Figure 1c shows the model of a PANTS node, which ...