What is an OLT?
OLT (Optical Line Terminal) is the core central office equipment in PON fiber access networks. It transmits downstream data from the IP network to ONU/ONT user terminals via PON ports, and aggregates upstream traffic from all users back to the upper network.
Key Factors for Choosing an OLT
1. PON Technology Standard
GPON OLT: ITU-T G.984, 2.488Gbps down / 1.244Gbps up. Global mainstream.
EPON OLT: IEEE 802.3ah, symmetric 1.25Gbps. Common in Asia.
XPON/Combo OLT: Supports both GPON and EPON ONUs. Ideal for transition periods.
XGS-PON OLT: 10G symmetric, GPON-compatible. For high-bandwidth needs.
2. PON Port Count & Density
- Mini OLT (4-8 ports): Compact, for small networks, rural broadband. Langzhi offers 4 and 8-port mini GPON OLTs.
- Mid-range OLT (16-32 ports): For towns and communities.
- Chassis OLT (48-128+ ports): Modular design, multiple line cards, hot-swappable, redundant power.
Capacity: 8-port OLT × 1:32 split = 256 users. 16-port × 1:32 = 512 users.
3. Uplink Interfaces
GE: Basic. 10GE: Recommended for medium networks. 25GE/40GE/100GE: For large carrier networks. Recommend uplink bandwidth = 20-30% of total PON port bandwidth.
4. Split Ratio Support
Common options: 1:32, 1:64, 1:128. Higher ratio = more users per port but stricter power budget. 1:32 is most common for FTTH.
5. Management Features
NMS/EMS system, CLI and Web management, VLAN configuration, QoS policies, OMCI remote ONU management.
6. Optical Power Budget
B+ class: 28dB budget. C+: 32dB. C++: 35dB. Choose C+/C++ for long distance or high split ratio.
OLT Selection Table
| Scenario | OLT Type | Config |
|---|---|---|
| Small network/rural | Mini 4-8 port OLT | 8×GPON + 2×GE + 1:32 |
| Medium town | 16-32 port chassis | 16×GPON + 4×10GE + redundant PSU |
| Large city | Large chassis OLT | 48-128×GPON + 10GE/100GE + hot-swap |
| Enterprise/campus | 8 port mini OLT | XPON + 4×GE + ACL security |
Conclusion
Choosing the right OLT requires considering user scale, PON standard, port density, uplink bandwidth, power budget, and management features. Langzhi Technology offers a complete range from mini to chassis OLTs, with full ONU and splitter product lines for one-stop FTTH solutions.
