Category Archives: BiDi Optical Transceiver

Overview of 1000BASE-BX SFP Bidi Transceiver

In communication networks, many transmission lines need bidirectional transmission. This need leads to the development of Bidirectional (BiDi) transceivers, which can transmit and receive data to/from interconnected equipment through a single optical fiber. BiDi transceivers are fitted with wavelength division multiplexing (WDM) diplexers, which combine and separate data transmitted over a single fiber based on the wavelengths of the light. 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. In this post, a kind of BiDi transceiver, 1000BASE-BX SFP BiDi transceiver will be introduced.

Introduction

1000BASE-BX is a part of the Gigabit Ethernet standard related to transmission over fiber optic cable. 1000BASE-BX SFP modules are compliant with SFP Multi-Source Agreement (MSA) specification and SFF-8472, and conform to the IEEE 802.3ah 1000BASE-BX10 standard. 1000BASE-BX SFP modules include 1000BASE-BX-U SFP module and 1000BASE-BX-D SFP module. These two SFP modules must be used in pairs to permit a bidirectional Gigabit Ethernet connection using a single strand of single mode fiber (SMF) cable. These transceivers transmit and receive signals on one fiber strand using two wavelengths in each direction. These hot pluggable optical transceivers consist of two sections: the transmitter section uses 1490nm DFB laser/1310nm Fabry-Perot laser, and the receiver section uses 1310nm/1490nm receiver accordingly. The 1000BASE-BX-D SFP operates at wavelengths of 1490nm TX/1310nm RX, and the 1000BASE-BX-U SFP operates at wavelengths of 1310nm TX/1490nm RX. These transceivers use standard simplex LC connectors for fiber cable connection and provide a long transmission distance of up to 10 km.

Key Features
  • Data rate up to 1.25 Gbps
  • Hot-pluggable SFP footprint
  • 1490 nm DFB Transmitter and 1310 nm PIN Receiver
  • 1310 nm FP Transmitter and 1490 nm PIN Receiver
  • Transmission distance up to 10 km
  • Simplex LC connector
  • Low power dissipation
  • Digital diagnostic monitor interface is compliant with SFF-8472
  • Compliant with SFP MSA Specification
  • Compliant with IEEE 802.3z Gigabit Standard
  • RoHS compliance
1000BASE-BX-D SFP

1000BASE-BX-D SFP supports link length of up to 10km point to point on single mode fiber (1490nm-TX/1310nm-RX wavelength) at 1Gbps bidirectional. This optic uses an LC connector. The picture below show a Cisco GLC-BX-D compatible 1000BASE-BX-D SFP 1490nm-TX/1310nm-RX transceiver. The GLC-BX-D is a small form factor pluggable module for Gigabit Ethernet 1000BASE-BX and Fiber Channel communications. The GLC-BX-D transceiver operates at 1490Tx/1310Rx wavelength. It is compatible with the IEEE 802.3ah 1000BASE-BX10-D standards. A 1000BASE-BX-D device is always connected to a 1000BASE-BX-U device with a single strand of standard SMF.

Cisco GLC-BX-D Compatible 1000BASE-BX-D SFP DOM Transceiver

1000BASE-BX-U SFP

1000BASE-BX-U SFP supports link length of up to 10km point to point on single mode fiber (1310nm-TX/1490nm-RX wavelength) at 1Gbps bidirectional. This optic uses an LC connector. The communication over a single strand of fiber is achieved by separating the transmission wavelength of the two devices. 1000BASE-BX-D transmits a 1490nm channel and receives a 1310nm signal, whereas 1000BASE-BX-U transmits at a 1310nm wavelength and receives a 1490nm signal. A wavelength-division multiplexing (WDM) splitter integrated into the SFP to split the 1310nm and 1490nm light paths. The GLC-BX-D and GLC-BX-U SFPs also support digital optical monitoring (DOM) functions according to the industry-standard SFF-8472 multisource agreement (MSA). This feature gives the end user the ability to monitor real-time parameters of the SFP, such as optical output power, optical input power, temperature and transceiver supply voltage. The picture below show a Cisco GLC-BX-U compatible 1000BASE-BX-U SFP 1310nm-TX/1490nm-RX transceiver.

Cisco GLC-BX-U Compatible 1000BASE-BX-U SFP DOM Transceiver

Applications
  • Gigabit Ethernet
  • Fiber Channel Links
  • Switch to switch interface
  • Switched backplane applications
  • Pouter/Server Interface
  • Other optical transmission systems
Conclusion

New organizational applications, virtualization, and data center consolidation trends are pushing your server I/O requirements to meet higher needs than before. With new BiDi optical technology, SFP BiDi transceivers make it much easier for you to upgrade your networks.

Choice of Bidirectional Transceivers for 40 GbE

As a result of data center consolidation, server virtualization, and new applications that require higher data transport rates, 10Gbps infrastructure is becoming overwhelmed by today’s data center requirements, making the shift to 40 and 100 Gbps inevitable, especially in the network aggregation layer and core. How to upgrade the cabling infrastructure and migrate to the 40Gbps era in a cost-effective way? Cisco 40G QSFP (quad small form-factor pluggable) bidirectional (BiDi) technology provides a feasible and effective method, which will be introduced in the following text.

What Is 40G QSFP BiDi Transceiver?

Cisco’s innovative 40 Gbps QSFP BiDi transceiver is a pluggable optical transceiver with a duplex LC connector interface for short-reach data communication and interconnect applications. The Cisco BiDi transceiver supports link lengths of 100m and 150m on laser-optimized OM3 and OM4 multimode fibers. It complies with the QSFP MSA specification, enabling customers to use it on all QSFP 40 Gbps platforms to achieve high-density 40 Gigabit Ethernet networks.

How Does 40G QSFP BiDi Transceiver Work?

Cisco QSFP BiDi transceiver technology converts four channels each of 10Gbps transmit and receive signals to two bidirectional channels of 20Gbps signals, which means that the Cisco QSFP BiDi transceiver has two 20Gbps channels, each transmitted and received simultaneously over two wavelengths on a single MMF strand. The technology uses specialized, multilayer, thin-film dielectric coating and lensing, which allows components to both pass and reflect optical signals at the same time. And it uses Bidirectional Optical Sub-Assembly (BOSA) technology to support two wavelengths (20 Gbps total) on each fiber. The connection can reach 100 meters on OM3 MMF or 150 meters on OM4 MMF, which is the same as 40Gbps SR4. Picture below shows the technology concept of the Cisco QSFP BiDi transceiver.

Concept of Cisco QSFP BiDi Transceiver

Why Choose 40Gbps QSFP BiDi Transceiver?

The Cisco QSFP BiDi transceiver transmits full-duplex 40Gbps traffic over one dual-fiber LC connector OM3 or OM4 MMF cable. It provides the capability to reuse 10Gbps fiber infrastructure. In other words, it enables data center operators to upgrade to 40Gbps connectivity without making great changes to the previous 10Gbps fiber cable plant. By using the existing 10 Gigabit Ethernet duplex multi-mode fiber (MMF) infrastructure for 40 Gigabit Ethernet, the Cisco BiDi transceiver offers significant cost savings and simplifies data center upgrading. It allows for zero-cost fiber migration by reusing the current 10Gbps cabling for 40Gbps device connectivity. 40Gbps QSFP BiDi transceiver reduces overall costs and installation time for customers migrating data center aggregation links to 40Gbps connections. Using Cisco BiDi transceivers offers 75% less fiber and MPO requirements, reduced cable sprawl and rack footprints, and investment protection with future support for 100 Gbps over duplex fiber.

Conclusion

Cisco 40G QSFP BiDi technology removes 40Gbps cabling cost barriers for migration from 10Gbps to 40Gbps connectivity in data center networks. It is quite a competitive option among all those various choices for 40 Gigabit Ethernet applications, such as QSFP+ transceiver, QSFP+ breakout cable or active optical cable. Compared with them, Cisco 40G QSFP BiDi transceivers provide simpler and less expensive 40Gbps connectivity compared to other 40Gbps transceiver solutions. Anyway, you choose the most appropriate one for your applications.

BiDi Optical Transceiver Overview

Many modern optical transceivers utilize two fibers to transmit data between switches, firewalls, servers, routers, etc. One fiber is dedicated to receiving data from networking equipment, and the other is to transmit data to the networking equipment. Nowadays, a new optical transceiver technology is available which allows transceivers to both transmit and receive data to/from interconnected equipment through a single optical fiber. This technology now has led to the development of Bi-Directional transceivers, or BiDi transceivers for short.

What Is BiDi Optical Transceiver?

BiDi optical transceiver is a compact optical transceiver module used in optical communications for both telecommunication and data bidirectional communications applications. It interfaces a network device mother board, like a switch, router or similar device, to a fiber optic or unshielded twisted pair networking cable. It is a popular industry format supported by several fiber optic component vendors. In the industry there are several synonyms for Bidi optics, such as: Bi-directional optics, BX-D/BX-U, WDM and so on. Specifically, the SFP-1G-BX-D and SFP-1G-BX-U are for the 1G. BIDI 1G optics are a small form factor pluggable module for single mode Fast Ethernet, Gigabit, Fiber Channel, SDH/SONET applications. BiDi SFP can be produced either with SC or LC simplex port, that is used both transmission and receiving. The most typical wavelength combination is 1310/1490, 1310/1550, 1490/1550 and 1510/1570. For a link you need 2 different optics, one that sends 1310nm and receives 1490nm and the other side of the fiber, which has a Bidi optic which sends 1490nm and receives 1310nm. In most cases these wavelengths are mentioned as Tx (transmitting) and Rx (receiving) on the label of the optic.

How Do BiDi Transceivers Work?

The primary 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, like GLC-BX-U and GLC-BX-D branded by Cisco, are being used to connect Device A (Upstream) and Device B (Downstream), as shown in the picture below, then:

BIDI transceiver working principle

  • Transceiver A’s diplexer must have a receiving wavelength of 1490nm and a transmit wavelength of 1310nm
  • Transceiver B’s diplexer must have a receiving wavelength of 1310nm and a transmit wavelength of 1490nm
Why Choose BiDi Transceivers?

The obvious advantage of choosing BiDi transceivers, such as SFP+ BiDi or SFP BiDi 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, or 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.

Fiberstore offers a large selection of BiDi transceivers branded by many famous companies, like Cisco, Juniper, and HP. BiDi SFP transceivers in Fiberstore can be produced either with SC or LC simplex port. And the typical wavelength combinations, such as 1310/1490, 1310/1550 and 1490/1550, are all available. For example, J9142B and J9143B branded by HP are paired BiDi SFP transceivers, using 1310nm/1490nm transmitter and 1490nm/1310nm receiver.