Overview of BiDi Transceiver Modules

During optical transmission process, it’s no wonder that using one fiber to receive data from networking equipment, and another one to transmit data to the networking equipment. This kind of transmission mode will increase investment cost certainly. Luckily, here is a type of transceiver can solve this problem. It’s bi-directional transceiver. Today, this article will take you to make sense why BiDi transceiver can make it possible to transmit data over one fiber.

Basics of BiDi Transceiver

BiDi is short for bidirectional. BiDi transceiver is a type of fiber optic transceiver which is used WDM (Wavelength Division Multiplexing) bi-directional transmission technology so that it can achieve the transmission of optical channels on a fiber propagating simultaneously in both directions. BiDi transceiver is only with one port which uses an integral bidirectional coupler to transmit and receive signals over a single fiber optical cable. Thus, it must be employed in pairs.

How Does BiDi Transceiver Work?

The obvious difference between BiDi transceivers and traditional two-fiber fiber optic transceivers is that BiDi transceivers are fitted with Wavelength Division Multiplexing (WDM) couplers, also known as diplexers, which combine and separate data transmitted over a single fiber based on the wavelengths of the light. For this reason, BiDi transceivers are also referred to as WDM transceivers.

To work effectively, BiDi transceivers must be deployed in matched pairs, with their diplexers tuned to match the expected wavelength of the transmitter and receiver that they will be transmitting data from or to.

For example, if paired BiDi transceivers are being used to connect Device A (Upstream) and Device B (Downstream), as shown in the figure below, then:

  • Transceiver A’s diplexer must have a receiving wavelength of 1550nm and a transmit wavelength of 1310nm
  • Transceiver B’s diplexer must have a receiving wavelength of 1310nm and a transmit wavelength of 1550nm

bidi transceiver diagram

Common Types of BiDi Transceiver

BiDi SFP Transceiver

BiDi SFP transceiver is typically applied for the high-performance integrated duplex data link over a single optical fiber. It interfaces a network device mother board (for a switch, router or similar device) to a fiber optic or unshielded twisted pair networking cable. And the most typical wavelength combination is 1310/1490 nm, 1310/1550 nm, 1490/1550 nm and 1510/1570 nm. This BiDi SFP transceiver is used in optical communication for both telecommunication and data bidirectional communications applications.

BiDi SFP+ Transceiver

BiDi SFP+ transceiver is an enhanced SFP transceiver. It is designed for bi-directional 10G serial optical data communications such as IEEE 802.3ae 10GBASE-BX by using 1330/1270nm transmitter and 1270/1330nm receiver. And its transmission distance is up to 20 km.


Advantages of BiDi Transceiver

The obvious advantage of utilizing BiDi transceivers, such as BiDi SFP+ and BiDi SFP transceivers, is the reduction in fiber cabling infrastructure costs by reducing the number of fiber patch panel ports, reducing the amount of tray space dedicated to fiber management, and requiring less fiber cable.

While BiDi transceivers (a.k.a. WDM transceivers) cost more to initially purchase than traditional two-fiber transceivers, they utilize half the amount of fiber per unit of distance. For many networks, the cost savings of utilizing less fiber is enough to more than offset the higher purchase price of BiDi transceivers.


In summary, BiDi transceivers can combine and separate data transmitted over a single fiber based on the wavelengths of the light. That is to say, to achieve the same transmitting result, it needs less money. Except for above SFP & SFP+ BiDi transceivers, FS.COM also provides 40G BiDi transceiver. This BiDi transceiver has two 20 Gbps channels, each transmitted and received simultaneously on two wavelengths over a single MMF strand (OM3 or OM4). Any one of the transceivers would meet your different application requirements with high performance.

Related ArticleA Brief Introduction of BiDi SFP Transceiver

Three Common High Density Host Ports – SFP+, QSFP+ and CXP

The push behind users’ requests for high-quality video content, whether for live Internet video or video downloads from servers, is the principal driver of extremely high growth of Internet traffic. Besides, more and more complex technical computing applications are demanding even greater bandwidth. In such cases, these SFP+, QSFP+ and CXP high density host ports are used to increase the bandwidth, enabling the high speed networking connections. This article gives an overview of these three ports, including their cabling solutions and bandwidth density.

High Speed Solutions: SFP+, QSFP+ and CXP Ports

Leading companies and industry organizations related to telecommunications have made their great efforts to develop specifications to assure commonality, compatibility and networking functionality of hardware connections, signaling and software communications. These specifications for high speed networking solutions include SFP+, QSFP+ and CXP links.

SFP+ Ports

In today’s data center, SFP+ links are supplanting SFP links for both Ethernet and Fibre Channel. Using the same board space as SFP, SFP+ provides a 10x bandwidth improvement over SFP for Ethernet (10Gb/s vs. 1Gb/s) and 2x improvement for Fibre Channel (8.5Gb/s vs. 4.25Gb/s). The SFP+ system also offers capability to freely designate or configure any available system port with either copper- or fiber-based cabling as dictated by the specific installation environment.

QSFP+ and CXP Ports

The other two high speed parallel link specifications which allow for even higher bandwidth are QSFP+ and CXP systems. The QSFP+ system uses a 4 x 10 Gb/s link configuration for a 40Gb/s port. Similarly, the CXP system provides 12 lanes that can be deployed to support 100 to 120Gb/s aggregated port bandwidth. QSFP+ and CXP are specified for 4x and 12x Infiniband Quad Data Rate (QDR) interconnect links. CXP ports can also be used for 40G links.

Comparison Among SFP+, QSFP+ and CXP Ports

The comparison among these three ports starts form their cabling solutions, then bandwidth density.

Three Common Cabling Solutions for SFP+, QSFP+ and CXP

The SFP+, QSFP+ or CXP host ports can accept either a passive copper-based cable solution for generally cable lengths of 5 to 7 meters, an active copper-based cable solution for typical cable lengths up to 15meters (or longer depending on the acceptance criteria), or a plug-in optical transceiver module with an optical connector on the rear of the module to accept passive fiber optic cable assemblies to enable even longer cable lengths. These cabling approaches enable flexibility to configure the cables needed to cater to different working environments. Take QSFP+ copper cabling solutions for example, Intel XLDACBL5 is the QSFP+ to QSFP+ passive copper cable assembly designed for 40-gigabit links with the distance up to 5m. Fiberstore compatible Intel XLDACBL5 is shown below.

A Fourth Cabling Solution for QSFP+

With the widespread use of QSFP+ for Ethernet transmission in high performance computing systems, there emerged a fourth cabling solution: active optical cable (AOC) assembly. In an AOC, the optical fiber is terminated directly to an optical transceiver that is sealed within the metal backshell on each end of the cable assembly. The integrated electro-optical assembly lowers cost in component reduction and presents an electrical interface to the outside world. Like 721070-B21 module, Fiberstore compatible HP 721070-B21 is the QSFP+ to 4SFP+ breakout AOC assembly used for 40G links.

Bandwidth Density

The SFP+, QSFP+ or CXP host ports can increase I/O port bandwidth density along the edge of a switch line card. A single SFP+ port operating at 10Gb/s provides about 16 Gb/s bandwidth per inch, QSFP+ offers 3x improvement to 48Gb/s per inch, and CXP offers a further 2.3x improvement to 113 Gb/s per inch. The port configurations give system designers options to achieve even higher linear bandwidth density with
some port types.


These high density SFP+, QSFP+ and CXP ports can provide increased communications bandwidth for data center networking. Fiberstore offers various SFP+, QSFP+ and CXP ports, and their cabling solutions. These cabling modules are fully compatible with major brands, like Intel (XLDACBL5), HP (721070-B21), Dell and Force 10 (CBL-QSFP-40GE-PASS-1M). You can visit Fiberstore to know more about SFP+, QSFP+ and CXP ports.

Cisco Leads 100G Ethernet Switch Market

In first quarter of 2013, the worldwide Ethernet switch market was $ 4.7 billion, decreased by 8% compared with 2012Q4, but an increase of 1%. 40G is the only port shipment growth products, an increase of 2%, which was mainly due to 40G fixed switches (such as 16xQSFP+) and chassis-based switches 40G line cards. Cisco is the early leader in 100G Ethernet switch port.

Due to the influence of seasonal factors, in first quarter of 2013, the Ethernet switch sales fell, but the past three quarters, the overall is still increased, taking into account the continued weakness in Europe and the U.S. federal government expense decreased , this is a positive signal.

In first quarter of 2013, port shipments fell 4%. 10G, which is generally considered as a star product, the chain fell highest.

40G is the only port shipment growth products, an increase of 2%, which was mainly due to 40G fixed switches (such as 16xQSFP +) and chassis-based switches 40G line cards.

Almost all of the Ethernet switch equipment manufacturers on a quarter-on-quarter drop.

Cisco is the early leader in 100G Ethernet switch port.