network topology
Enable an agent to recognise a network's arrangement of nodes and connections, assess structural constraints and vulnerabilities, and identify topology changes that warrant further validation.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
recalled by Codex without web access - no source was read
Researched by: Codex
Purpose and description
Enable an agent to recognise a network's arrangement of nodes and connections, assess structural constraints and vulnerabilities, and identify topology changes that warrant further validation.
Network topology is the arrangement of nodes and links in a communication network, describing either their physical interconnection or their logical connectivity at a specified network layer.
It can be Construct and compare physical, logical and overlay views using explicit endpoint identities.; Trace candidate structural paths and identify the additional forwarding evidence needed to establish usable connectivity.; Locate isolated components, articulation points and bridge connections within a declared graph view.; Assess alternative paths against node, link and shared-failure dependencies.; Compare intended and observed snapshots to identify additions, removals and disputed connections.; Evaluate proposed node or connection changes and define structural checks for validation and rollback..
Distinguishing features
Describes which endpoints are connected at a stated layer; a device inventory alone does not establish a topology.
Distinguishes installed connections from logical adjacencies: a logical connection may traverse several physical links.
Represents structural path possibilities; a routing table describes selected forwarding behaviour and may expose only part of that structure.
Retains node and connection meaning independently of drawing coordinates; moving symbols on a diagram does not necessarily change topology.
Requires an explicit scope and observation interval; disconnected components in a partial map do not by themselves establish a network outage.
Scope
+ Network boundary, included nodes, connection endpoints and external attachment points
+ Physical, logical and overlay topology views and their mappings
+ Connection direction, multiplicity, shared-medium structure and structural patterns
+ Structural connectivity, path alternatives and failure dependencies
+ Observed, intended and historical topology states with evidence and uncertainty
+ Proposed structural changes and the conditions for validating them
- Hardware specifications, procurement and lifecycle of individual network devices
- Packet formats and detailed routing or switching protocol behaviour
- Traffic demand, application behaviour and measured service performance
- Security policies, credentials and authorisation decisions
- Cable materials, civil engineering and facility construction
- General mathematical topology and networks outside the adopted communications scope
Characteristics
- Topology view
- physical, logical, overlay; specify represented network layer Determines what counts as a node, connection and valid structural inference.
- Boundary membership
- included nodes and segments, excluded regions, external attachment points Prevents conclusions about a mapped subset from being applied to an entire network.
- Connection semantics
- directed or undirected; point-to-point or shared medium; single or parallel Controls how adjacency and paths can be interpreted.
- Node and connection counts
- counts under a declared node, link and shared-segment counting convention Supports comparison between snapshots without confusing representation changes with network growth.
- Node degree
- incident-connection count per node; in-degree and out-degree for directed views Identifies attachment concentration and structurally isolated nodes.
- Structural pattern
- point-to-point, star, ring, bus, tree, partial mesh, full mesh, hybrid or unclassified Summarises arrangement while requiring the underlying connections to support the label.
- Structural connectivity
- component count; weak or strong components for directed graphs; pairwise path existence Shows which endpoints can be connected structurally under the declared interpretation.
- Failure dependency
- nodes and connections mapped to shared devices, media, conduits, power supplies or other failure domains Reveals when apparently separate paths share a cause of failure.
- Realisation state
- intended, observed, reconciled or disputed; with validity interval Prevents a design or stale observation from being treated as the current arrangement.
- Evidence coverage
- complete within declared scope, partial or unknown; with observation timestamps and unresolved adjacencies Qualifies conclusions that depend on missing or outdated topology information.
Also called
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 5 bundles · 9 layers · 15 findings · 23 questions.
Topology boundary and views Establishes which network arrangement is represented and what its elements mean.
Connectivity conclusions are unreliable when network boundaries or abstraction layers are mixed.
Network membership
Defines the mapped region and the treatment of its interfaces with other networks.
Included elements and external attachments
Record the membership rule, included elements and boundary connections, including any omitted or opaque regions.
- Which devices, interfaces, segments or virtual endpoints count as nodes in this topology? definition
- Where does the mapped network end, and how are connections into excluded regions represented? boundary
Physical, logical and overlay views
Separates arrangements at different layers and connects them through explicit mappings.
View semantics and underlay mapping
Record the represented layer and known mappings from logical or overlay elements to their supporting network structure.
- Does an edge mean an installed physical connection, a layer-specific adjacency or an overlay relationship? definition
- What evidence maps each logical connection to its underlying nodes and links, and where is that mapping unknown? provenance
Adjacency and structural patterns Captures connection semantics and the patterns supported by actual adjacency.
Topology labels alone cannot describe parallel links, shared media, directionality or hybrid arrangements.
Connection representation
Defines endpoint identity and how different connection forms are represented.
Endpoint and medium semantics
Record connection endpoints, direction and multiplicity, and represent shared media without implying unsupported independent links.
- Which exact endpoints participate in each connection, and is that relationship directed or bidirectional? definition
- Are parallel links and multi-access segments represented explicitly, aggregated, or expanded into pairwise edges? boundary
Pattern and scale
Describes local and overall arrangement using reproducible structural measures.
Pattern supported by adjacency
Associate pattern labels with the subgraphs and counting conventions that support them, allowing mixed structures.
- Which observed adjacencies justify a star, ring, tree, bus or mesh label, and to which subgraph does that label apply? definition
- What are the node counts, connection counts and degree distributions under the chosen representation? measurement
Connectivity and failure structure Evaluates structural paths, separation and dependencies that affect continuity.
An agent must distinguish graph connectivity from operational reachability and apparent redundancy from independent alternatives.
Components and paths
Examines structural connectivity for specified endpoints and edge-selection rules.
Structural path availability
Record components and candidate paths while identifying the operational facts needed to determine whether traffic can use them.
- Which components and endpoint-to-endpoint paths exist when only connections eligible for this analysis are included? measurement
- Which forwarding, policy or operational-state facts remain necessary before a structural path can be treated as usable? boundary
Cuts and shared failures
Examines elements and common dependencies whose loss could separate required endpoints.
Independence of alternative paths
Identify relevant cuts and assess path alternatives against declared failure scenarios, including shared supporting infrastructure.
- Which node or connection removals would disconnect the endpoint pairs that must remain connected? measurement
- Which alternative paths share an underlying device, conduit, power source or other failure dependency? provenance
Topology evidence and change Tracks how topology assertions are supported, reconciled and altered over time.
Discovered maps, design diagrams and current network arrangements can diverge, affecting every structural assessment.
Snapshot evidence
Associates topology assertions with observation methods, coverage and validity intervals.
Observed versus intended adjacency
Record the evidence for each relevant node and connection and distinguish absent connections from unobserved ones.
- Which discovery output, configuration record, inspection or design document supports each asserted adjacency, and when was it obtained? provenance
- Where do intended and observed arrangements disagree, and which missing connections may reflect incomplete discovery? measurement
Structural change validation
Defines proposed topology changes and the structural conditions they must preserve or establish.
Change impact and postconditions
Describe node and connection changes, evaluate affected connectivity and dependencies, and specify validation evidence.
- Which nodes or connections would be added, removed or remapped, and which required paths or failure protections would change? action
- Which observations will confirm the intended post-change topology, and what structural condition should trigger rollback? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Check these first
Recalled without web access and unsourced; every item is a lead to verify.
- No sense was recorded; this description assumes communication networks rather than mathematical topology or another application of networks.
- Physical and logical topologies can differ, and a topology description should identify its network layer and what counts as a node or link.
- The listed standards support topology discovery or control in particular network technologies; they are not universal requirements for every topology.
- Which of these check these first hold for the sense of network topology this model covers, and on what evidence? provenance
Kinds and varieties
Recalled without web access and unsourced; every item is a lead to verify.
- Bus
- Star
- Ring
- Mesh, including full and partial mesh
- Tree
- Hybrid
- Which of these kinds and varieties hold for the sense of network topology this model covers, and on what evidence? provenance
Standards and regulation
Recalled without web access and unsourced; every item is a lead to verify.
- IEEE 802.1AB, issued by IEEE, specifies Link Layer Discovery Protocol for discovering adjacent network devices and their connections.
- IEEE 802.1Q, issued by IEEE, specifies bridges and bridged networks, including mechanisms that control active forwarding topology.
- RFC 2328, published by the IETF, specifies OSPF Version 2, a routing protocol that maintains link-state topology information.
- Which of these standards and regulation hold for the sense of network topology this model covers, and on what evidence? provenance
Real-world use
Recalled without web access and unsourced; every item is a lead to verify.
- Designing local-area, wide-area and data-centre networks.
- Planning redundant paths and assessing resilience to equipment or link failures.
- Computing routes and controlling packet forwarding.
- Mapping connectivity for troubleshooting and network inventory.
- Evaluating capacity bottlenecks and expansion options.
- Which of these real-world use hold for the sense of network topology this model covers, and on what evidence? provenance
Typical measurements
Recalled without web access and unsourced; every item is a lead to verify.
- Node degree in a simple undirected graph - 0 to N−1 for a network with N nodes; these are mathematical bounds, not an empirical typical range. - incident links per node
- Graph density in a simple undirected graph - 0 to 1 for N greater than 1. - dimensionless
- Hop diameter of a connected simple undirected graph - 1 to N−1 for N greater than 1; disconnected graphs require a separate convention. - hops
- Which of these typical measurements hold for the sense of network topology this model covers, and on what evidence? provenance
Failure modes and hazards
Recalled without web access and unsourced; every item is a lead to verify.
- A central node or critical link can become a single point of failure.
- Insufficient path redundancy can allow failures to partition the network.
- Forwarding loops can circulate traffic and, in bridged networks, contribute to broadcast storms.
- Traffic concentrated through a few links or nodes can cause congestion.
- Apparently independent logical paths may share physical infrastructure and fail together.
- Which of these failure modes and hazards hold for the sense of network topology this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Recalled without web access and unsourced; every item is a lead to verify.
- Network architecture - Architecture specifies roles, protocols and design principles; topology specifies which nodes are connected and how.
- Routing - Routing selects paths through a network; topology describes the connectivity on which those selections operate.
- Network protocol - A protocol defines rules for communication; topology describes the arrangement of communicating nodes and links.
- Graph - A graph is a mathematical structure that can represent topology; a network topology assigns network meaning to its nodes and links.
- Topology in mathematics - Mathematical topology studies spaces and continuity; communication-network topology usually concerns graph connectivity.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of network topology this model covers, and on what evidence? provenance
What the second pass must settle
- Does vr.tr.network-topology cover communications networks only, or should its scope include other network arrangements?
- Does an existing Vercy world model already own this concept, requiring the registry entry to link to it?
- Which node granularity, network layers and shared-medium representations are required by the intended agent tasks?
- Which evidence sources are authoritative for observed topology, and what freshness and coverage requirements apply?
- Which endpoint pairs, failure scenarios and shared dependencies define acceptable connectivity and redundancy for a particular use?