The 400G-BIDI Module from Arista is Capable of being Broken out into 4x 100G-BIDI or 4x 100G-SR1.2 Links. What is the Difference Between 100G-BIDI and 100G-SR1.2?

Picture of FiberMall

FiberMall

Answered on 9:02 am

The difference between 100G-BIDI and 100G-SR1.2 is mainly in the number of optical lanes and the modulation solution. 100G-BIDI uses two optical lanes, one for each direction, over a duplex LC multi-mode fiber. 100G-SR1.2 uses four optical lanes, two for each direction, over the same fiber. 100G-BIDI uses NRZ (Non-Return-to-Zero) modulation, which means each bit is encoded as a single symbol. 100G-SR1.2 uses PAM4 (Pulse Amplitude Modulation) modulation, which means each symbol encodes two bits. PAM4 enables higher data rates with lower baud rates, but also introduces more noise and complexity. Both 100G-BIDI and 100G-SR1.2 are compliant to IEEE802.3bm 100GBASE-SR4 standard. The main advantage of 100G-BIDI is that it can reuse the existing 40G-BIDI infrastructure and reduce the fiber cabling cost. The main advantage of 100G-SR1.2 is that it can interoperate with 400G-SR4.2 and provide a future-proof solution for higher bandwidth demand.

Another difference between 100G-BIDI (100G-SRBD) and 100G-SR1.2 is the FEC (Forward Error Correction) used. 100G-BIDI (100G-SRBD) modules have been widely deployed for 100G operation over duplex MMF and use a FEC implementation that was developed prior to the IEEE standardization of KP-FEC for 50G PAM-4 based modules. Because of the differences in FEC implementation, 100G-SRBD and 100G-SR1.2 modules are not interoperable with each other.

People Also Ask

CCWDM vs CWDM: When Compact CWDM Actually Pays Off

A CCWDM (Compact CWDM) module performs the same wavelength multiplexing and demultiplexing functions as a conventional CWDM module, but uses a more compact optical architecture. By integrating thin-film filters into a free-space micro-optical assembly, it reduces internal fiber interconnections and can lower insertion loss while significantly reducing package size. Both

NVIDIA RoCEv2 Configuration Guide: Mastering Spectrum-4, ConnectX, and Spectrum-X End-to-End Lossless Networking

Building a high-performance AI cluster requires more than powerful GPUs and high-speed Ethernet switches. Network congestion, packet loss, and inconsistent RDMA configurations can significantly reduce distributed training efficiency. NVIDIA RoCEv2 enables Remote Direct Memory Access (RDMA) over routable Ethernet networks, reducing CPU involvement and supporting high-throughput GPU communication. Combined with NVIDIA

DAC Cable vs Optical Module: Reach, Power, and Cost per Link

A DAC cable is usually the better choice for short, fixed data center links under about 3 m, where cost, power consumption, and latency are important considerations. An optical module paired with fiber is generally the better choice when a link needs to reach farther, connect through patch panels, support

CWDM Distance Limits: How Far CWDM Can Reach

How far can CWDM transmit? The answer depends on the data rate, operating wavelength, optical power budget, fiber characteristics, and passive component losses. Typical CWDM transceiver specifications cover a wide range of distances. At 10G, shorter-wavelength modules are commonly rated for 10 to 40 km, while selected longer-wavelength modules support

Passive vs Active DAC Cable: Reach, Power & When to Use

Passive and active DAC cables both transmit electrical signals over shielded twinax copper. The key difference is how they handle signal degradation. Passive DAC cables rely on the host SerDes for signal transmission and equalization, while active copper cables add signal-conditioning electronics inside the connectors. These electronics may use analog

CWDM OADM: Add-Drop Design Guide for Ring Networks

A CWDM OADM adds and drops selected wavelengths at an intermediate site while all other channels continue along the express path without being dropped or converted. Use one when one or more channels need to leave or join a fiber mid-span. Use a mux/demux at terminal sites, where all channels

Related Articles

800g sr8 and 400g sr4

800G SR8 and 400G SR4 Optical Transceiver Modules Compatibility and Interconnection Test Report

Version Change Log Writer V0 Sample Test Cassie Test Purpose Test Objects:800G OSFP SR8/400G OSFP SR4/400G Q112 SR4. By conducting corresponding tests, the test parameters meet the relevant industry standards, and the test modules can be normally used for Nvidia (Mellanox) MQM9790 switch, Nvidia (Mellanox) ConnectX-7 network card and Nvidia (Mellanox) BlueField-3, laying a foundation for

Read More »
CWDM vs CCWDM

CCWDM vs CWDM: When Compact CWDM Actually Pays Off

A CCWDM (Compact CWDM) module performs the same wavelength multiplexing and demultiplexing functions as a conventional CWDM module, but uses a more compact optical architecture. By integrating thin-film filters into a free-space micro-optical assembly, it reduces internal fiber interconnections and can lower insertion loss while significantly reducing package size. Both

Read More »
NVIDIA RoCEv2

NVIDIA RoCEv2 Configuration Guide: Mastering Spectrum-4, ConnectX, and Spectrum-X End-to-End Lossless Networking

Building a high-performance AI cluster requires more than powerful GPUs and high-speed Ethernet switches. Network congestion, packet loss, and inconsistent RDMA configurations can significantly reduce distributed training efficiency. NVIDIA RoCEv2 enables Remote Direct Memory Access (RDMA) over routable Ethernet networks, reducing CPU involvement and supporting high-throughput GPU communication. Combined with NVIDIA

Read More »
dac cable vs optical module

DAC Cable vs Optical Module: Reach, Power, and Cost per Link

A DAC cable is usually the better choice for short, fixed data center links under about 3 m, where cost, power consumption, and latency are important considerations. An optical module paired with fiber is generally the better choice when a link needs to reach farther, connect through patch panels, support

Read More »
CWDM distance

CWDM Distance Limits: How Far CWDM Can Reach

How far can CWDM transmit? The answer depends on the data rate, operating wavelength, optical power budget, fiber characteristics, and passive component losses. Typical CWDM transceiver specifications cover a wide range of distances. At 10G, shorter-wavelength modules are commonly rated for 10 to 40 km, while selected longer-wavelength modules support

Read More »
passive vs active dac cable

Passive vs Active DAC Cable: Reach, Power & When to Use

Passive and active DAC cables both transmit electrical signals over shielded twinax copper. The key difference is how they handle signal degradation. Passive DAC cables rely on the host SerDes for signal transmission and equalization, while active copper cables add signal-conditioning electronics inside the connectors. These electronics may use analog

Read More »
cwdm oadm

CWDM OADM: Add-Drop Design Guide for Ring Networks

A CWDM OADM adds and drops selected wavelengths at an intermediate site while all other channels continue along the express path without being dropped or converted. Use one when one or more channels need to leave or join a fiber mid-span. Use a mux/demux at terminal sites, where all channels

Read More »
Scroll to Top