114 lines
2.3 KiB
Markdown
114 lines
2.3 KiB
Markdown
# Cable Length Calculation
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## Goal
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Estimate practical cable lengths from the physical arrangement of devices in a rack so users can preselect realistic patch and power cable variants.
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The result should support planning, not exact installation certification.
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## Use cases
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- patch cable length between patch panel and switch
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- DAC or fiber estimate between devices in the same rack
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- power cable estimate from PDU to active device
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- BOM generation for preconfigured cable sets
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## V1 approach
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Cable length should be estimated from:
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- rack unit position of both components
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- side of connection: front or rear
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- optional port offsets
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- route style
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- slack factor
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## Suggested routing model
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For V1, use a rule-based path estimate instead of full geometric routing.
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### Inputs
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- source component `U` position
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- target component `U` position
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- source and target side
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- rack depth
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- routing preference
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- slack percentage or fixed reserve
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### Routing preferences
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- `front_vertical`
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- `rear_vertical`
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- `front_to_rear`
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- `shortest_practical`
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## Example calculation logic
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Estimate length as:
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1. vertical distance between source and target mounting positions
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2. plus horizontal or side transition allowance
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3. plus front/rear traversal allowance
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4. plus slack reserve
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Illustrative formula:
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```text
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estimated_length =
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vertical_distance_mm
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+ side_transition_mm
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+ front_rear_allowance_mm
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+ service_loop_mm
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```
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Then round up to the next marketable cable length, for example:
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- `0.25 m`
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- `0.5 m`
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- `1.0 m`
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- `1.5 m`
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- `2.0 m`
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- `3.0 m`
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## Accuracy strategy
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The tool should display:
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- raw estimated length
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- recommended order length
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- confidence note such as `estimate only`
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## Data requirements
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Better cable estimation becomes possible if components expose ports with offsets.
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Minimum V1:
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- component `U` position only
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Better V1:
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- per-port offsets in the component metadata
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## BOM integration
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Cable entries can be generated as:
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- one line per connection
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- or aggregated by cable type and recommended order length
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Example:
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- `12 x RJ45 patch cable Cat6A, 0.5 m`
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- `4 x C13 to C14 power cable, 1.5 m`
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## Future improvements
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- front and rear cable manager objects
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- reserved routing channels
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- left/right side path selection
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- bend radius constraints
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- color-coded cable groups
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- cross-rack cable planning
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