Electrical reach
Confirm the host channel can close the passive copper loss at the exact rate.
Product guides
DAC vs AOC: A Decision Guide for Data-Centre Links
Choose the cable architecture from the installed path and operating model—not from unit price or connector appearance.
A passive DAC carries the electrical interface through twinax copper and normally offers the lowest power and latency at short reach. Its practical limit is set by channel loss, cable gauge, bend load, connector mass and the host electrical budget.
An AOC converts the electrical interface to fibre inside the cable ends. It reduces cable bulk and extends reach, but adds active components, power draw and an optical failure domain that must be handled as a complete cable assembly.
MingApex coordinates China-based sourcing, OEM execution and independent quality-control evidence. It is not presented as the product manufacturer or an accredited laboratory; supplier identity, method and evidence boundary remain explicit.
01 / Decision inputs
Freeze the variables before comparing options
Freeze the installed route and port requirements; catalogue length alone is not enough.
| Required input | What to record | How it changes the decision |
|---|---|---|
| Host and port | Exact switch/NIC, software, port mode and allowed cable type | Some ports restrict passive reach or active-cable identity. |
| Data rate and lanes | Native rate, lane count and breakout mode | Electrical lane budget changes by architecture. |
| Installed length | End-to-end routed length with service loops | Catalogue length must cover the real route. |
| Cable pathway | Tray fill, bend radius, airflow and pull force | Copper bulk may create mechanical or thermal risk. |
| Power budget | Allowed port power and rack power policy | AOC consumes active power at both ends. |
| Service model | Replaceable unit, sparing and fault isolation | AOC is replaced as a complete active assembly. |
| Commercial scope | Quantity, coding, lead time and warranty terms | Total deployed cost is more than cable unit price. |
02 / Engineering comparison
Compare on measurable engineering criteria
Compare both options on the same route, port and operating assumptions.
Mechanical loading
Check cable diameter, connector weight, bend radius and tray density.
Power and heat
Record per-end AOC power and its effect on port/rack thermal margin.
Latency and signal path
Keep protocol latency separate from physical propagation and active conversion.
Fault operations
Define diagnostics, spare ratio and replacement ownership for each architecture.
03 / Product anchors
Live product examples for a controlled starting point
These live SKUs anchor the physical family. Suitability still depends on the documented host, fibre path and validation scope.
Live product page100G QSFP28 Passive DAC CablePassive copper cable baselineLive product page100G QSFP28 SR4 100m MPO TransceiverParallel multimode polarity referenceLive product page200G QSFP56 FR4 2km LC TransceiverPAM4 and 200G lane referenceLive product page400G QSFP-DD DR4 500m MPO TransceiverParallel-SMF and breakout reference
A product page is a starting specification, not universal compatibility or lot-acceptance evidence.
04 / Decision patterns
Choose by evidence, not shorthand
The preferred option changes with route, power and service constraints.
Preferred path
Use passive DAC for a short, mechanically manageable route when the named ports support the exact length and electrical channel.
Conditional path
Use AOC when reach, tray density or airflow favours fibre, subject to port recognition, power and complete-cable replacement acceptance.
Stop and redesign
Redesign when the route exceeds passive electrical reach and active-cable power, bend or service constraints are also unacceptable.
Revalidation trigger
Revalidate any host, port mode, cable length, gauge, AOC chipset, coding profile or routing change.
05 / Validation path
From requirement lock to approved order line
Validate the full installed channel, not a loose cable on an unrelated bench.
- 1
Freeze the requirement
Record the exact host, port, data rate, reach, fibre path and commercial scope for DAC vs AOC.
- 2
Compare complete architectures
Include optics, fibre, connectors, power, cooling, software and operational constraints—not only unit price.
- 3
Define measurable acceptance
Set loss, telemetry, link, error, traffic and documentation criteria before selecting the sample.
- 4
Validate the named configuration
Test the serialized sample on the recorded setup and close deviations with an owner and deadline.
- 5
Bridge approval to production
Match the approved identity, revision, coding and critical attributes to the production lot and repeat order.
06 / Risk control
Failure modes that invalidate the decision
Length shorthand
Nominal length ignores route and service loops.
Port assumption
A connector fit is treated as protocol approval.
Thermal blind spot
AOC power is omitted from rack calculations.
Repair mismatch
A complete AOC is treated like field-terminated fibre.
07 / Evidence
Downloadable process references
08 / Buyer questions
Guide-specific questions
What does this guide decide?
The decision covers the named host ports, cable length, routing path, thermal environment and service model. A passing DAC or AOC sample does not approve every port or length.
What must the buyer provide?
Provide both endpoint models, port mode, exact routed length, tray/bend constraints, power policy, quantity and spare strategy.
When is the preferred path conditional?
Use AOC when reach, tray density or airflow favours fibre, subject to port recognition, power and complete-cable replacement acceptance.
What must be revalidated?
Revalidate any host, port mode, cable length, gauge, AOC chipset, coding profile or routing change.
Connected authority paths
Continue through compatibility, quality and evidence
Controlled next step
Compare the real cable path before choosing DAC or AOC.
Send the two hosts, rate, length, routing restrictions, quantity and spare policy for a bounded recommendation.