Pipeline Publishing, Volume 4, Issue 4
This Month's Issue:
Maintaining Network Health
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Self-* Networks: Helping Networks
Help Themselves

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What part of nature actually helps in purposeful systems design?

Common to most of these groups are biological systems as models for building autonomic communications. We understand that these bio-models, and the organizations engaged in research in their use, can appear to be a little pie-in-the-sky. Much of the research in application of nature-based designs to networks and information systems is very abstract and currently out of reach of real problems and solutions. However, nature is still useful as analogy and a source of inspirations for application patterns.

Today, the environment is the self-* framework in which the agents or services interact.

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  1. Design stimuli and controls;
  2. Deploy & watch how these affect the complex system, and
  3. Reproduce & disseminate the patterns which work.

The use of stimuli closely follows a basic observation of complex systems in nature.

Stigmergy is a method of indirect communication in a self-organizing emergent

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Fundamentally, building networks and applications is still a matter of design, not evolution or chance. One concludes that autonomic communications, as idealistically expressed above, is still out of reach. Today we must concentrate on patterns which reflect the purposeful design of networks, services, and support systems. Fortunately, architecting and coding self configuring, self-healing systems is not only possible; it’s been done - again and again by different groups.

In part one (last month’s), Autonomic Networks, we comment: “Nature is not designed. All the interactions have been worked out by minute changes in the activities of the individual species acting over a long change. Ecosystems have no team with the job of network designer creating the pretty schematic…” We however have the possibility of introducing active design. These designed patterns are then fed into what is actually an existing complex system of network elements, connections, services, and support systems. The key is that the stimuli and the micro behavior driving the complete system can be purposefully designed. Further, like a deity, we can observe these systems from the outside, see what works as we wish, and replicate that successful pattern to other parts of the systems environment. So it is a three step approach,

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system where its individual parts communicate with one another by modifying their local environment.”

The term [stigmergy] is also employed in experimental research in robotics, multi-agent systems and communication in computer networks. In these fields there exist two types of stigmergy: active and passive. The first kind occurs when a robotic or otherwise intelligent "agent" alters its environment so as to affect the sensory input of another agent. The second occurs when an agent's action alters its environment such that the environmental changes made by a different agent are also modified. A typical example of active stigmergy is leaving behind artifacts for others to pick up or follow. An example of passive stigmergy is when agent-A tries to remove all artifacts from a container, while agent-B tries to fill the container completely.” [Wikipedia]

This indirect control is fundamental to how self-* systems are built today.

Architecture of Self-* Systems

Returning again to Dan Druta of AT&T, he clearly desires some core basics features of self-healing systems:

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