Connection of trunk cables and optical fibers

Trunk cables serve as the backbone of fiber optic networks, connecting multiple optical fibers via pre-terminated connectors like MPO/MTP, LC, or SC for high-speed, reliable data transmission.

Overview of Trunk Cables

Fiber optic trunk cables are multi-fiber assemblies designed to carry large volumes of data over long distances, forming the backbone of structured cabling systems in data centers and telecom networks. They typically consist of multiple optical fibers enclosed in a protective sheath, often reinforced with aramid yarn for tensile strength, and terminated with connectors at both ends for plug-and-play deployment. Trunk cables can support single-mode (OS2) or multimode fibers (OM1–OM5), with higher-grade fibers like OM3–OM5 optimized for longer distances and higher bandwidths.

Types of Connectors

Trunk cables use pre-terminated connectors to simplify installation and ensure consistent performance: MPO/MTP connectors: Multi-fiber push-on connectors that allow high-density connections, commonly used in 40G, 100G, and 400G networks.

MT

P is a high-performance variant of MPO with improved alignment, durability, and signal integrity. MPO/MTP trunks often come in Base-8, Base-12, or Base-16 configurations, supporting 8–16 fibers per connector row.

L

C connectors: Small form-factor connectors with a 1. 25 mm ferrule, ideal for high-density racks due to their compact size.

S

C connectors: Larger 2. 5 mm ferrule connectors with a push-pull mechanism, suitable for both single-mode and multimode applications.

Connection Methods

Trunk cables are typically pre-terminated and factory-tested, allowing rapid deployment without field splicing. The connection process involves: Routing the trunk cable through conduits, cable trays, or raised floors. Aligning connectors with patch panels, cassettes, or transceivers, ensuring proper polarity and minimal insertion loss.

Using harness or fan-out cables when a multi-fiber trunk needs to be split into individual fibers for connection to transceivers or end devices. For example, an MPO-to-LC harness converts a multi-fiber trunk into multiple single-fiber connections. Securing and protecting connectors with factory-installed pulling eyes or protective sleeves to prevent damage during installation.

Practical Considerations

Polarity management is critical to ensure correct signal flow between transmitters and receivers. Insertion loss and return loss must be minimized, especially in high-speed networks, with ultra-low-loss trunks (≤0. 25 dB) recommended for 400G/800G deployments.

Connector type selection depends on space constraints, fiber count, and network architecture.

L

C connectors are preferred for high-density racks, while MPO/MTP trunks are ideal for backbone links.

Summary

Connecting trunk cables and optical fibers involves selecting the appropriate fiber type, connector, and trunk configuration, routing the cable securely, and using pre-terminated or fan-out assemblies to interface with network equipment. Proper installation ensures high-speed, reliable, and scalable network performance across data centers and telecom infrastructures.