I. Overview

In today's data center networks, most fiber cabling is built for 10Gbps connectivity. When data centers need to speed up from 10Gbps to 40Gbps, the question is how to achieve speed up from 10Gbps to 40Gbps at low cost. Since the cabling for 10Gbps uses two-core LC patch cables, while the cabling for 40Gbps has to use 8-core MPO patch cables. So in order to support 40Gbps connectivity, data center architects will need to deprecate all existing 10Gbps cabling and reinvest in 40Gbps fiber optic cabling. This is a costly and wasteful solution. The solution to this problem is the innovative 40Gbps QSFP Bidi technology, which enables 40Gbps connectivity on top of the existing 10Gbps fiber cabling. Greatly save fiber optic cabling investment, but also to avoid the waste of fiber optic resources.

Second, the use of existing 40G optical modules to face the problem

Common transmission rate of 40Gbps short distance transmission optical module is 40G QSFP SR4 optical module. This optical module uses the QSFP package form, the use of independent transmitter and receiver parts, each optical module has four parallel fiber transmitters, plus four parallel fiber receiver, signal transmission requires eight fibers. qsfp sr4 uses MPO 8-core fiber. The following figure shows how a 40G QSFP optical module works.

The connection between two 40G QSFP optical modules requires an MPO-to-MPO 8-core fiber. A problem arises when the data center network cabling is built for 10Gbps transmission. 40G QSFP optical modules cannot directly transmit 40Gbps using LC to LC fiber, and require an 8-core fiber. It is important to know that the number of fiber cores for LC to LC is 2 cores. Due to the characteristics of 40G QSFP optical modules, customers need to invest 4 times the cost of fiber to speed up their existing data centers from 10Gbps to 40Gbps.

40G QSFP Bidi Optical Module Solution

QSFP Bidi Optical Module can speed up the transmission rate from 10Gbps to 40Gbps by connecting dual-core multimode fiber with LC interface, which means that QSFP Bidi Optical Module can realize 40Gbps transmission on the basis of existing 10Gbps fiber optic cabling without any additional investment in fiber optics.

QSFP Bidi Optical Module is a short-distance transmission optical module for use over multimode fiber, with a maximum transmission distance of 100 meters over OM3 fiber and 150 meters over OM4 fiber;

The interface type of QSFP Bidi optical module is dual LC interface; the working wavelength is 850nm/890nm; the device complies with MSA standard.

QSFP Bidi Optical Module The QSFP Bidi Optical Module has two signaling channels, each with a transmission rate of 20 Gbps; each channel can perform transmit and receive operations on two wavelengths simultaneously. This allows for a 10Gbps speed boost to 40Gbps at the access layer over two multimode LC fibers.

The following figure shows the working principle of 40G QSFP Bidi optical module

Summary

40G QSFP Bidi technology solves the problem of updating fiber optic cabling for data center networks from 10Gbps to 40Gbps. Compared with other 40G QSFP optical modules, 40G QSFP Bidi optical modules can meet 40Gbps transmission rate while saving 4 times of fiber investment, and also save a lot of labor costs. Using 40G QSFP Bidi optical modules can realize 40Gbps transmission from the existing 10Gbps cabling base, and the transmission rate can be accelerated through lower investment. Clearly, 40G QSFP Bidi modules are the most cost-effective solution for accelerating your existing 10Gbps transmission to 40Gbps.

Additional Learning Hub Resources 

Cisco 400G QSFP-DD Optical Transceivers Overview 

800G OSFP Optical Transceiver Module Overview 

what is 400G QSFP-DD optical module？ 

How to choose an appropriate optical fiber jumper for the QSFP-DD 800G optical module