What protocols are supported by this 155M SFP family?
These are multi-rate modules designed for flexibility. They support OC-3 for SONET networks, STM-1 for SDH networks, and Fast Ethernet (100BASE-FX) for data networks. The specific protocol is determined by the configuration of the host device's port.

What is the maximum distance these transceivers can support?
This product family offers a wide range of distance options, starting from 2km for short-reach applications and extending up to 80km for long-haul telecommunication links.

Do you offer single-fiber (BiDi) versions for 155M?
Yes, we offer BiDirectional (BiDi) transceivers for 155M applications. These are ideal for environments with fiber constraints, as they transmit and receive data over a single strand of fiber using different wavelengths. They must be deployed in matched pairs.

Which wavelength should I choose for a 40km link?
For a 40km link, you have two options: a 1310nm module (LEP-H31-40D) or a 1550nm module (LEP-H55-40D). The 1550nm version generally offers a better link budget margin due to lower fiber attenuation at that wavelength, making it a more conservative choice for links approaching the maximum distance.

Are these modules compatible with older networking equipment from vendors like Cisco or Juniper?
Our transceivers are designed for broad compatibility with MSA-compliant platforms. They are frequently used in legacy equipment from major vendors. However, we always recommend verifying compatibility with your specific hardware model and software version prior to large-scale deployment.

What type of fiber optic cable is required for these SFPs?
All transceivers in this 155M SFP family are designed for use with standard single-mode fiber (SMF) and typically use LC connectors.

What is the difference between the LEP-B3155-20D and LEP-B5531-20D BiDi modules?
These are a matched pair. The LEP-B3155-20D transmits at 1310nm and receives at 1550nm. TheLEP-B5531-20D does the opposite, transmitting at 1550nm and receiving at 1310nm. You must use one of each at opposite ends of the single fiber link for it to function.

Can I use these SFPs for a new network installation?
While these modules are perfect for maintaining or expanding existing 155M networks, for new installations, we generally recommend evaluating higher-speed technologies like 1G or 10G Ethernet unless your application has a specific requirement for OC-3/STM-1 rates.

Distance selection
2km – short inter‑rack/campus connections. 10km – typical access loop. 20km – extended campus or metro ring. 40km – regional transport (1310nm or 1550nm). 80km – long‑haul without intermediate amplification (1550nm only).

Wavelength selection
For distances ≤40km, 1310nm is cost‑effective on standard single‑mode fibre. For 40km and 80km, 1550nm provides lower attenuation and can coexist with DWDM/CWDM channels if future upgrades are planned.

Connector & fibre type
All variants use LC duplex connectors on single‑mode fibre (SMF). BIDI models require a single SMF strand; ensure the paired transceivers (LEP‑B3155‑xxD and LEP‑B5531‑xxD) are used as a matched set.

Dual‑fibre vs BIDI
Dual‑fibre – lower per‑port cost, simple inventory. BIDI – saves fibre, ideal for leased fibre or where fibre ducts are full, but requires the paired transceiver at the far end.

Migration & upgrade paths
The compact SFP form factor allows these modules to be swapped into SFP ports on routers, switches, and SDH add‑drop multiplexers. For bandwidth growth, consider upgrading to 1.25GbE SFP or SFP+ families while preserving the same mechanical footprint.

SDH/SONET Access Networks
The 155M SFP family supports STM‑1 (SDH) and OC‑3 (SONET) rates, making it suitable for metro access rings and last‑mile aggregation. Pair short‑reach 2km modules for intra‑office links and 20km–40km modules for inter‑site rings.

Fast Ethernet Backhaul
Leverage dual‑fiber 1310nm variants for Fast Ethernet (FE) backhaul over existing single‑mode fibre. 10km and 20km modules are ideal for campus and metro Ethernet networks.

Fibre‑Savvy BIDI Deployments
Use BIDI transceivers (1310/1550nm and 1550/1310nm pairs) over a single fibre to halve fibre utilisation. Suitable for point‑to‑point connections where fibre is scarce, such as rural broadband and building interconnect.

Long‑Reach Applications
Deploy 1550nm 80km variants for long‑haul backhaul or protected rings that require extended reach without amplifiers. For longer distances (>80km), consult your Lightrend representative for custom solutions.

Migration from Legacy PDH/SDH
Replace obsolete PDH interfaces with standard 155M SFP transceivers on modern multi‑service platforms while preserving existing fibre infrastructure. BIDI options can simplify fibre migration.

Extending Legacy SONET/SDH Rings:
Cost-effectively add new nodes or extend the reach of existing telecom transport rings without replacing the entire infrastructure.

Upgrading 100BASE-FX Campus Backbones:
Replace older, fixed-port Fast Ethernet media converters with flexible SFP-based switches for improved management and reliability.

Last-Mile Fiber to the Business (FTTB):
Provide reliable 155 Mbps symmetrical service delivery to enterprise customers over existing fiber infrastructure.

Industrial and Utility Network Connectivity:
Connect remote SCADA systems, substations, or industrial controllers over long distances with robust and reliable fiber links.

Connecting Disparate Buildings:
Use BiDi variants to link two buildings with a single strand of dark fiber, saving costs on fiber leasing or installation.

Temporary Event or Broadcast Links:
Quickly establish point-to-point 155 Mbps links for video transport or data backhaul where dedicated fiber is available.