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IEEE 802.3ae 10GBASE-BX is a physical layer specification in the 10G Ethernet standard that specifically defines single fiber bidirectional 10G transmission. Its core value lies in the ability to achieve full duplex 10Gbps transmission with only 1 core fiber, saving 50% of fiber resources compared to traditional dual fiber solutions.
What is IEEE 802.3ae?
IEEE 802.3ae is the foundational standard for 10G Ethernet, officially approved and published by the IEEE Standards Committee in June 2002. This standard defines the MAC (Media Access Control) parameters, physical layer specifications, and management parameters for 10Gbps Ethernet. IEEE 802.3ae defines three physical coding sub–layers (PCS):
| Sub–layer Type | Encoding Methods | Remark |
| 10GBASE-X | 8B/10B | 4 parallel 3.125G channels (such as CX4) |
| 10GBASE-R | 64B/66B | Mainstream LAN PHY, including LR, ER, SR, BR |
| 10GBASE-W | 64B/66B + WIS | WAN PHY, compatible with SONET/SDH frame structure |
Among them, 10GBASE-BX (or 10GBASE-BR) belongs to the 10GBASE-R series and uses 64B/66B encoding.
Detailed Introduction of 10GBASE-BX Technology
10GBASE-BX Meaning
| Item | Meaning |
| 10G | 10 Gbps speed |
| BASE | Baseband transmission |
| BX | Bi-X directional (single fiber bidirectional) |
| BR | Technically accurate name (Bi directional R) |
Note: Technically, the more accurate name is 10GBASE-BR, as this specification belongs to the 10GBASE-R series, but is commonly referred to as 10GBASE-BX in the industry.
Technical Specification
| Parameter | Value |
| transmission rate | 10.3125 Gbps（9.95~11.3 Gbps） |
| interface type | Simplex LC |
| fiber type | Single mode fiber (SMF, 9/125 μ m) |
| Wavelength configuration | 1270nm (TX)/1330nm (RX) or vice versa |
| transmission distance | 10km/20km/40km (depending on the model) |
| encoding method | 64B/66B |
| work mode | Full duplex (through different wavelengths) |
Wavelength pairing: 10GBASE-BX must be used in pairs
The 10G SFP+ BIDI optical transceiver adopts wavelength division multiplexing (WDM) technology, which uses two different wavelengths to complete transmission and reception on the same core fiber. Modules must be used in pairs, and the wavelengths at both ends need to be paired:
| Model type | Transmitting wavelength (TX) | Receiving wavelength (RX), | Transmission direction |
| BXD（Downstream） | 1330nm | 1270nm | From the center to the user end |
| BXU（Upstream） | 1270nm | 1330nm | From the user end to the center |
Comparison of Different Distance Versions
The 10G SFP+ BIDI optical transceivers can be divided into multiple versions based on transmission distance:
| Model | Transmission distance | Ttransmit power | Receiver sensitivity | Wavelength configuration | Typical applications |
| SFP-10G-BX10 | 10km | -6 ~ +1 dBm | ≤ -14.4 dBm | 1270nm / 1330nm | Park interconnection, 10GBASE-BX |
| SFP-10G-BX20 | 20km | -2 ~ +3 dBm | ≤ -14.5 dBm | 1270nm / 1330nm | Metropolitan access, cross regional backbone |
| SFP-10G-BX40 | 40km | +0.5 ~ +5 dBm | ≤ -15.5 dBm | 1270nm / 1330nm | Metropolitan aggregation, ultra long distance links |
The link budget of the 20km version is about 4dB higher than that of the 10km version, which can better cope with accumulated losses such as fiber aging and multiple jumper connections.
Compatibility Requirements
Physical Compatibility
| Item | Remark |
| Encapsulation | SFP+MSA (Multi Source Protocol) standard |
| Electrical interface | Compatible with standard 10GBASE-LR module electrical interface |
| Management interface | SFF-8472 Digital Diagnosis (DDM/DOM) |
Network device compatibility
Mainstream network equipment manufacturers all support the 10GBASE-BX standard:
| Equipment manufacturers | Corresponding compatible model example |
| Cisco | SFP-10G-BXD-I / SFP-10G-BXU-I |
| Huawei | SFP-10G-BXD2 / SFP-10G-BXU2 |
| Juniper | EX-SFP-10GE-BX32-20 |
| Dell | GP-SFP-10GBX-U-20 |
| MikroTik | S+32LC10U |
BIDI SFP+ Transceiver Certification and Compliance
Industrial grade version
Some 10GBASE-BX modules offer industrial grade (I-temp) versions:
| Version | Working temperature | Suitable applications |
| Commerical | 0°C ~ 70°C | Data center, indoor computer room |
| Industrial | -40°C ~ +85°C | 5G base station, outdoor cabinet |
Standard compliance
- IEEE 802.3ae-2002:10G Ethernet Basic Standard
- BiDi specification for 10GBASE-BR: 64B/66B encoding
- SFF-8472: Digital Diagnostic Monitoring Interface
- SFP+MSA: Packaging and Electrical Interface Specification
Recommend Modules for Different Applications
| Scene | Recommended module | Recommendation reasons |
| 10G upgrade with tight fiber optic resources | SFP-10G-BX10 | Upgrade using a single backup fiber optic cable |
| Metropolitan area access and aggregation | SFP-10G-BX20 | Connect aggregation layer and access layer nodes |
| Backbone interconnection in the park | SFP-10G-BX10 | Connecting core switches of different buildings |
| Long distance DCI/metropolitan aggregation | SF 10G BX40D I | Ultra long distance data center interconnection |
| 5G prequel | Industrial Temp SFP-10G-BX10 or SFP-10G-BX20 | Outdoor base station deployment |
Conclusion
IEEE 802.3ae 10GBASE-BX is a physical layer standard for single fiber bidirectional transmission in 10G Ethernet. It uses 64B/66B encoding and achieves full duplex 10Gbps transmission on a single fiber through wavelength division multiplexing technology, saving 50% of fiber resources. It is the core technology standard for 10G upgrade in scenarios where fiber resources are scarce.
| Item | Key points |
| Standard positioning | IEEE 802.3ae physical layer specification, defining single fiber bidirectional 10G transmission |
| Technical ownership | 10GBASE-R series, using 64B/66B encoding |
| Interface features | Single LC, only requires 1 core fiber, saving 50% of resources |
| Transmission distance | 10km/20km/40km (depending on the model) |
| Key technology | Must be used in pairs, with paired wavelengths at both ends (1270nm/130nm) |
| Temperature level | Commercial grade (0~70℃)/Industrial grade (-40~85℃) |
