An Introduction to Cisco`s QSFP28 100G FR (Single Lambda)

When it comes to network implementation, you may only think of pluggable optics secondarily. However, in recent years, high-performance and high-capacity pluggable transceivers have been developed to meet the growing bandwidth requirements in service provider and data centre networks. As a result, the design of pluggable modules and their communication with the host ports of routers and switches has become increasingly complex. Today, 100G optics are considered a viable solution to the design and hardware costs of our network fibre infrastructure.

Cisco is one of the leading manufacturers in the networking industry. The simple design of Cisco's 100G pluggable optics reflects a reduced number of internal components. According to Cisco, they tend to scale manufacturing cost and volume to the scale of 10G SFP+ optics. Using signal processing technology and silicon photonics, Cisco has introduced the vision of 100G single-lambda optics. Once the new generation form factors are available, you will be able to transition incrementally - one site at a time. The new generation form factors will also allow you to upgrade to 400G platforms.

QSFP-100G-FR-S is the first, 100G single-lambda product from Cisco. This pluggable optical module is offered in QSFP28 form factor and it comes featured with PAM4 modulation capability. The QSFP-100G-FR-S with all the specifications as defined by the 100G Lambda MSA for 100G-FR transceivers.

This module uses duplex LC connectors and it has a maximum reach of 2km over duplex single-mode fiber (SMF). The reach, fiber type, and connector of the QSFP-100G-FR-S module are equivalent to CWDM4 – one of the most popular choices in data centers. You can use this module in any application where CWDM4 has been used.

In QSFP-100G-FR-S, the electrical interface consists of four lanes (25Gbps each). The received electrical signal is then converted to 2 x 50Gbps PAM4 lanes and then into one lane of 100Gbps PAM4. A DSP is utilized for this two-step conversion.

The single lambda module requires only one laser for its 100Gbps PAM4 lane, significantly reducing the design complications. However, DSPs have their complexities related to cost and power consumption. The QSFP-100G-FR-S module can only be deployed for short reach (below and up to 2km) because of the high chromatic dispersion.

• QSFP28 100G FR is the first product from Cisco`s line of 100G Single-Lambda family
• This module is developed to fully comply with the 100G Lambda MSA`s specifications from 100G-FR
• QSFP28 100G FR offers 2km reach over duplex SMF (single-mode fiber) and uses duplex LC connectors.
• FR can be integrated with any network configuration where CWDM4 has been used.