Overview

The Panduit/Cisco paper on Passive Optical Networks: Cabling Considerations and Reference Architectures explores how enterprises can evolve beyond traditional Ethernet LANs by adopting Passive Optical LAN (POLAN). This approach reduces energy consumption, minimizes space requirements, and aligns bandwidth delivery with actual user needs.

Distributed Edge Architecture

A key highlight is the distributed edge architecture enabled by zone cabling and enclosure‑based ONTs. Instead of centralizing electronics in telecom closets, ONTs can be deployed closer to endpoints in secure enclosures.

  • This decentralization reduces copper runs, simplifies moves/adds/changes, and mitigates congestion in telecom rooms.
  • It also supports scalable growth, as fiber backbones extend reach beyond copper limitations.
  • Cascaded splitter designs allow flexible provisioning, balancing bandwidth across IoT, automation, and user devices.

Passive Optical LAN (POLAN)

POLAN leverages singlemode fiber and optical splitters to deliver Gigabit and future 10G XGS‑PON services.

  • Structured cabling ensures testability, maintainability, and long‑term scalability.
  • Reference architectures include brownfield upgrades (using existing copper), greenfield FTTE (fiber to the enclosure), and large‑scale centralized fiber deployments.
  • POLAN reduces OpEx by lowering power and cooling demands, while providing a future‑ready path for IoT and smart building integration.

Distance and Split Ratios

Designing a POLAN requires careful trade‑offs between reach, bandwidth per user, and split ratios:

  • Reach: GPON supports up to 20 km from OLT to ONT; XGS‑PON extends this with higher power budgets.
  • Split ratios: Common configurations include 1:8, 1:16, 1:32, and 1:64. Higher splits reduce per‑ONT bandwidth but lower infrastructure costs.
  • Bandwidth allocation: A 1:32 split on 2.5 Gbps downstream GPON yields ~78 Mbps per ONT under full load; XGS‑PON (10 Gbps) scales proportionally.
  • Design rule: Campus designs often use 1:32 for general users and 1:16 or lower for high‑bandwidth zones (labs, server rooms, dense wireless).

Brownfield Migration Strategies

Most enterprises can’t replace their entire LAN overnight. Practical migration approaches include:

  • Phased deployment: Start with new construction or major renovations, then migrate building‑by‑building or floor‑by‑floor as budget allows.
  • Hybrid coexistence: Run POLAN alongside existing Ethernet switches during transition periods; aggregate both at the core.
  • Repurpose pathways: Existing conduit and cable trays can carry fiber; copper can often be left in place or reused for low‑speed legacy devices.
  • Pilot and validate: Deploy a single‑building or single‑floor pilot to train staff, validate designs, and build confidence before scaling.
  • Plan for ONT placement: Identify secure locations (IDFs, ceiling zones, equipment rooms) where ONTs can be powered and managed without disrupting operations.

Fault Managed Power (FMP)

While the paper focuses on cabling and optical design, Cisco and Panduit’s broader ecosystem integrates Fault Managed Power (FMP) for smart building applications. FMP extends the concept of Power over Ethernet (PoE) by enabling higher power delivery over longer distances with advanced safety features.

What Makes FMP Different

Traditional PoE is limited to 100 meters and typically maxes out at 90W (PoE++). FMP systems—also known as Class 4 Fault Managed Power—can deliver:

  • Higher power levels: Up to 450W per circuit (compared to PoE’s 90W limit)
  • Extended reach: Up to 2 km from power source to endpoint
  • Active fault management: Real‑time monitoring detects and isolates faults (shorts, opens, overloads) before they become hazards
  • Centralized control: Power policy, priority, and telemetry managed through a single controller

Hybrid Cables vs Separate Pathways

FMP can be deployed using hybrid fiber/power cables or separate fiber and power runs:

  • Hybrid cables: Single jacket combines singlemode fiber with DC power conductors. Ideal for:
    • New construction where pathway space is limited
    • Outdoor or plenum runs where reducing cable count matters
    • Endpoints that need both data and power (cameras, wireless APs, small switches)
  • Separate pathways: Run fiber and FMP power cables independently. Preferred when:
    • Retrofitting existing buildings with available conduit
    • Power and data have different maintenance cycles or ownership
    • Flexibility to upgrade one system without disturbing the other

Code Compliance and Safety

FMP systems fall under NEC Article 726 (Class 4 circuits) and must comply with:

  • UL 1400 certification for fault‑managed power equipment
  • Arc fault detection: Systems must detect and interrupt potential arc faults within milliseconds
  • Grounding and bonding: Clear requirements for DC power distribution and equipment grounding
  • Labeling: Cables and terminations must be clearly marked as Class 4 power circuits

These safety features make FMP suitable for installations where traditional PoE can’t reach or doesn’t deliver enough power.

Converged Infrastructure Benefits

Pairing POLAN with FMP creates a unified infrastructure stack:

  • Single backbone: Fiber carries both data (PON) and power (FMP conductors in hybrid cables)
  • Simplified telecom rooms: Eliminate both switches and local UPS units; centralize power and backup at the OLT/MDF
  • Resilient edge: FMP controllers can prioritize critical loads (life safety, security) during power events
  • Operational visibility: Both network and power telemetry flow through the same management platform

This convergence is especially powerful for smart buildings, where IoT density and edge computing demand scalable, manageable power delivery alongside high‑bandwidth connectivity.

Conclusion

Distributed edge architectures, combined with POLAN and FMP, represent a transformative shift in enterprise infrastructure. They reduce lifecycle costs, enhance flexibility, and prepare organizations for next‑generation bandwidth and power demands. With careful attention to split ratios, reach constraints, and phased migration strategies, enterprises can modernize their networks while maintaining operational continuity and positioning infrastructure for decades of growth.

Reference

Panduit. (n.d.). Passive optical networks: Cabling considerations and reference architectures. Retrieved December 16, 2025, from https://www.panduit.com/content/dam/panduit/en/website/documents/NI-ENT-passive-optical-networks-CPAT93–SA-ENG.pdf