How Does 100G BIDI Simplifies Data Center Cabling?

NADDOD Jason Dec 30, 2022

Mission-critical workloads such as artificial intelligence AI and machine learning are increasing compute and traffic demands within the fabric, driving a shift to denser, higher-speed connectivity in the data center within the leaf spine and backbone and between leaf spine/top-of-rack switches and servers.

Traditional data center upgrades from 10G to 40G or 100G require conversion from LC duplex cabling with SFP optical modules attached to MPO cabling with QSFP optical modules attached, adding to operational costs. How can we simplify cabling and reduce capital expenditure? Optical modules with BiDi solutions can do so, and 100G QSFP28 SR BiDi is one such product.

Much like the 40G QSFP+ SR BiDi optical module, the 100G QSFP28 SR BiDi allows data center operators to reuse their existing duplex LC patch infrastructure when upgrading from 10G SR or 40Gb BiDi to 100G. By upgrading network equipment one endpoint at a time, operators have the flexibility to upgrade their data centers.

The 100G QSFP28 SR BiDi is a parallel quad-channel small form factor pluggable (QSFP28) BiDi optical module that supports 100Gbps and the module is compliant with IEEE802.3bm 100GBASE-SR4. The module uses dual core duplex LC multimode fiber with 4 x 25G NRZ modulation on the electrical port side and converts to 2x50Gbps PAM4 modulation on the optical port side for a total bandwidth of PAM4 technology supports 50Gb data rate and 25Gbaud rate signal transmission.

100G links
The 100G QSFP28 SR BiDi is used in pairs for 100G connectivity and can also be connected to the 400G QSFP+ SR BiDi in 4×100G branch mode.

4x100G links

100G QSFP28 SR BiDi Advantage

Reduce CAPEX by reusing duplex LC multimode fiber infrastructure

Reduce operational expenses by seamlessly upgrading from 10 Gbps SR or 40 Gbps BiDi to 100 Gbps rates

Prepare for future network upgrades by providing connectivity at 400 Gbps rates

Reduce transmission errors with KP4 Forward Error Correction (FEC) at 100 Gbps data rates

Data Center Cabling with 100G QSFP28 SR BiDi

As shown below, the 400G QSFP-DD BiDi SR can be deployed in the spine layer that serves as the network backbone, with branch connections to leaf nodes. Deploy 100G QSFP28 SR BiDi in the backbone and leaf nodes, and upgrade the backbone nodes to 400G as bandwidth requirements grow.

leaf spine architecture
As shown below, considering the higher coverage and operational flexibility of pluggable optical modules compared to pre-assembled cables (DAC/AOC), operators can use 100G QSFP28 SR BiDi for top-of-rack connectivity to servers, or deploy 400G in TOR and use branch connections downstream to connect 1×400G QSFP-DD BiDi SR with 4×100G QSFP28 SR BiDi to servers.

switch to server