Perspectives
Networks Through a Systems Architect's Eyes
Network engineering makes the distinction concrete: topology matters, but routing policy, congestion, protocol state and failure behavior matter…
I approach networks with an occupational habit: I want to draw boxes and arrows. That habit is useful because architecture forces questions about state, boundaries, interfaces, resources and failure. It is dangerous because natural systems were not designed to respect our diagrams.
Networks describe entities and relations, but behavior also depends on direction, weight, timing, capacity and the process moving through the graph. Topology constrains behavior without uniquely determining it.
Where does state live?
Networks describe entities and relations, but behavior also depends on direction, weight, timing, capacity and the process moving through the graph. Topology constrains behavior without uniquely determining it.
Software gives us the expectation that important state should have an owner. Natural systems often distribute state across structure, concentrations, relationships and history. A snapshot can therefore tell us less than the process that produced it.
Where are the interfaces?
Network engineering makes the distinction concrete: topology matters, but routing policy, congestion, protocol state and failure behavior matter too.
Engineered interfaces are declarations. Natural boundaries are often material: membranes, tissues, ecological borders, channels, gradients or social conventions. They can leak, adapt and participate in the behavior they constrain.
What is the failure model?
A static graph freezes time. Living, technical and social networks can add and remove connections as a consequence of the very process flowing through them.
Failure analysis is useful because normal operation hides assumptions. A healthy component can coexist with an unhealthy whole. A local optimization can damage the larger system. Robustness at one level can create fragility at another.
History is part of the architecture
Graph theory began with abstract connectivity problems and became a general language for infrastructure, biology and social systems.
In a designed system, legacy structure may be accidental baggage. In an evolved or historically accumulated system, legacy structure can be the reason the current architecture exists at all. The path is not documentation around the system; sometimes it is part of the system.
The zoom test
A good architectural description should survive zooming. Going down a level should reveal mechanisms capable of implementing the higher-level pattern. Going up should reveal regularities that justify discussing the larger entity in its own vocabulary.
Networks encourage relational thinking: an entity's role may depend as much on its position among others as on intrinsic properties.
How much of identity is intrinsic, and how much is a position in a web of relationships?
Reading trail
These links are starting points for the scientific and historical ideas. The systems interpretation, analogies and conclusions here are my own.