medium dependent interface
Enable an agent to identify a medium dependent interface, assess its compatibility with a transmission medium and peer interface, and determine which connection, configuration, or verification actions are justified.
Bundle → Layer → Finding → Questions Filled
5 bundles · 9 layers · 15 findings · 23 questions
MDI identity and contract Establishes what boundary is being modeled and which Ethernet requirements govern it.
Medium-facing boundary
Locates the interface relative to the PHY or MAU and the transmission medium.
Boundary identification
Record the implementing objects on either side and the exact interface boundary, distinguishing the MDI from internal and MAC-facing interfaces.
- Where does the specified PHY or MAU meet the transmission medium? definition
- Which nearby connector, PHY sublayer, or MII-family interface could be mistaken for this boundary? boundary
Governing PHY profile
Connects the interface to a versioned set of requirements.
Profile and revision
Record the PHY designation and controlling clauses before assigning interface limits or declaring compatibility.
- Which standard edition, PHY clauses, amendments, and corrigenda define this MDI? provenance
- Which supported modes share this attachment, and which require a different MDI profile? boundary
Medium attachment and mapping Captures how the medium mates with the interface and how signal paths are assigned.
Mechanical mating
Identifies the attachment geometry and supported medium termination.
Attachment compatibility
Record the specified attachment, keying, and termination requirements rather than inferring compatibility from a familiar connector shell.
- Which connector or attachment specification and mating geometry apply? definition
- Does the proposed medium termination satisfy the required mating and keying constraints? action
Signal-path mapping
Describes contact, pair, lane, or fiber roles and applicable remapping behavior.
Mapping and crossover
Record path assignments and determine whether fixed crossover, automatic crossover, or polarity handling applies to this PHY.
- How are contacts, pairs, lanes, or fibers assigned to the signal roles required by this PHY? definition
- Which documented crossover or polarity behavior must be considered when selecting or troubleshooting the connection? action
Signal and power envelope Defines the profile-specific conditions under which signals and optional power cross the interface.
Electrical or optical envelope
Selects the relevant signal quantities and their specified limits.
Signal limits at the MDI
Record only the electrical or optical requirements applicable to the selected profile, including measurement conditions and reference planes.
- Which electrical or optical quantities and limit curves apply at this MDI reference plane? measurement
- Which test conditions and calibration or de-embedding procedures make the measured values comparable to those limits? measurement
Conditional power attachment
Handles power requirements only where the attachment supports a specified power role.
Power role and constraints
Record the applicable power role, conductor usage, and enabling requirements while leaving complete power-system behavior to neighboring models.
- Does this attachment have a documented PD or endpoint PSE role, or is it data-only? definition
- Which power specification and interface checks govern whether power may be enabled on the proposed connection? action
Compatibility and verification Turns interface requirements and observed evidence into bounded connection decisions.
Peer and medium fit
Compares the local MDI, transmission medium, and remote interface.
Connection assessment
Record compatible operating modes and unresolved attachment, mapping, or signal mismatches across the proposed connection.
- Which operating modes are jointly supported by the local interface, peer interface, and selected medium? boundary
- Which identified mismatch requires a configuration change, a different medium, or a different interface? action
MDI test evidence
Associates conformance decisions with reproducible interface measurements.
Conformance and diagnostic limits
Record test coverage, measured failures, and the limits of conclusions drawn from link status or end-to-end symptoms.
- Which test reports identify the tested port, PHY mode, reference plane, conditions, and governing limits? provenance
- What additional measurement would distinguish an MDI defect from a medium fault, peer fault, or internal PHY problem? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
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.
- Which of these check these first hold for the sense of medium dependent interface this model covers, and on what evidence? provenance
Kinds and varieties
Recalled without web access and unsourced; every item is a lead to verify.
- Which of these kinds and varieties hold for the sense of medium dependent interface this model covers, and on what evidence? provenance
Identifiers and schemes
Recalled without web access and unsourced; every item is a lead to verify.
- Which of these identifiers and schemes hold for the sense of medium dependent interface this model covers, and on what evidence? provenance
Standards and regulation
Recalled without web access and unsourced; every item is a lead to verify.
- Which of these standards and regulation hold for the sense of medium dependent interface this model covers, and on what evidence? provenance
Real-world use
Recalled without web access and unsourced; every item is a lead to verify.
- Which of these real-world use hold for the sense of medium dependent interface 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.
- Which of these failure modes and hazards hold for the sense of medium dependent interface 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.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of medium dependent interface this model covers, and on what evidence? provenance
Classifiers Filled
- Family
- Thing Registry
- Category
- Information and virtual systems
- Entry kind
- thing
- Plane
- INF
- Domain
- INF.KNW
What it is Filled
A medium dependent interface (MDI) is the interface between an Ethernet physical-layer device and its transmission medium, with characteristics specified for the particular Ethernet physical-layer type.
In scope
- Identification of the Ethernet PHY type, governing specification, and medium-facing interface boundary
- Mechanical mating requirements and contact, pair, lane, or fiber assignments
- Applicable electrical or optical signal requirements at the MDI reference plane
- Media attachment compatibility, including crossover behavior where applicable
- Conditional power delivery requirements at the same attachment boundary
- Evidence supporting interface conformance and permitted connection or configuration actions
Out of scope
- MAC framing, switching, routing, and application protocols
- Media independent interfaces between MAC and PHY, such as MII and GMII
- Internal PHY coding, signal processing, and implementation architecture
- Complete cable or fiber plant design and installation
- Connector products considered independently of their Ethernet interface assignment
- Complete powered-device or power-sourcing-equipment design
Why it exists Filled
Enable an agent to identify a medium dependent interface, assess its compatibility with a transmission medium and peer interface, and determine which connection, configuration, or verification actions are justified.
Distinguishing features Filled
- The boundary faces the transmission medium; a MAC-facing digital interface belongs to an MII-family model instead.
- Identification requires a PHY-specific attachment contract; connector appearance alone cannot establish that two MDIs are compatible.
- Electrical or optical requirements are assessed at an identified medium-facing reference plane, rather than at arbitrary internal PHY nodes.
- An MDI-X designation describes a crossover arrangement within applicable interfaces, rather than a separate networking layer.
- The entry represents an interface concept and its requirements; a cable, PHY chip, or connector is a related implementing object.
What robots and AI may and may not do Filled
Must not
- Connect to or tap a network medium it is not authorized to access.
- Change cabling or port settings on a live network without authorization.
- Apply power over cabling to equipment not designed to receive it.
Only with a human decision
- Changing physical connections on networks that carry critical services.
May
- Identify and document MDI port types and cabling on networks it is authorized to manage.
- Diagnose link problems such as crossover or pair mismatches and report them.
Moral aspects Filled
- Physical network access can expose others' communications.
Who is affected
- Network users
- Network administrators
- Organizations relying on the network
Owners Filled
Steward
The owner or operator of the network equipment.
Links to other meta-models Filled
parent
- Q6046311 - registry parent class
What else AI and robots need to interact with it Filled
Identity and identifiers required Filled
- Vercy registry: vr.tr.medium-dependent-interface
- Wikidata: Q1421871 (https://www.wikidata.org/wiki/Q1421871)
Direct properties not applicable Not applicable
- Governing PHY specification: Ethernet PHY designation, standard edition, applicable clauses, amendments, and corrigenda
- Transmission medium class: Balanced copper, optical fiber, coaxial, or another explicitly specified medium
- MDI reference plane: Specified physical boundary and associated measurement fixture or de-embedding convention
- Mechanical attachment profile: Connector or attachment specification, mating geometry, keying, and applicable contact assignment
- Signal-path assignment: Contacts, pairs, lanes, or fibers mapped to their PHY-specific roles
- Supported operating modes: Declared PHY modes, nominal bit rates in bit/s, and supported duplex or topology options
- Electrical interface measurements: Profile-dependent voltage in V, impedance in ohms, and return loss in dB over a stated frequency range; not applicable for optical-only measurements
- Optical interface measurements: Profile-dependent wavelength in nm and optical power in dBm, with measurement conditions; not applicable for electrical-only interfaces
- Crossover configuration: MDI, MDI-X, automatic selection, unknown, or not applicable, qualified by PHY type
- Power attachment role: Data-only, PD, endpoint PSE, unknown, or not applicable, with the governing power specification
- Interface verification status: Untested, partially tested, conformant for a stated profile, nonconformant, or indeterminate
Plane INF: no invented physical properties.
Recognition optional Filled
- A network port, such as an eight-pin modular socket or an optical connector, on an Ethernet device.
Capabilities and actions required Filled
- Resolve a port description into a PHY-specific MDI profile and identify missing evidence.
- Compare a proposed medium and peer interface against mechanical, signal, mapping, and operating-mode requirements.
- Determine whether crossover or automatic crossover settings are relevant to a connection problem.
- Select electrical or optical measurements at the correct MDI reference plane.
- Check conditional power attachment requirements before recommending power enablement.
- Recommend connection, reconfiguration, retesting, or replacement based on documented mismatches.
Hazards and failure modes required Filled
- Wrong pair wiring causes link failure or degraded speed.
- Incorrect power over Ethernet can damage connected equipment.
Standards and interfaces required Filled
- IEEE 802.3, Standard for Ethernet, Institute of Electrical and Electronics Engineers.
Context of use required Filled
- A medium dependent interface is encountered where an Ethernet physical-layer device connects to its specified transmission medium.
- It is used when assessing port, connector and cabling compatibility or diagnosing physical connection problems.
- Its requirements depend on the particular Ethernet physical-layer type and medium.
Sources Filled
- Wikidata item Q1421871: medium dependent interface - identity and sense of the item
- Wikipedia: Medium-dependent interface - general description of the item
Open questions
- Does the registry intend the general IEEE 802.3 interface concept or the narrower use of MDI contrasted with MDI-X on twisted-pair ports?
- Which existing Vercy model, if any, already owns this interface concept and should remain its single source of truth?
- Which PHY families and standard editions should receive detailed profiles, including applicable corrections to interface limits?
- How should the INF / INF.KNW classification distinguish the abstract interface contract from physical port implementations?
- Which power attachment variants and non-connector implementations must the initial model cover?
Machine files
Provenance
thing registry research (pass 2) · unreviewed
Built from: models/things/publications/thing-q1421871/spec.json