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Optical Transceiver Modules


  • Introduction to Bi-Directional Transceiver Modules

    Almost all modern optical transceivers utilize two fibers to transmit data between switches, firewalls, servers, routers, etc. The first fiber is dedicated to receiving data from networking equipment, and the second fiber is dedicating to transmitting data to the networking equipment. But there is a type of fiber optic transceiver module called BiDi (Bi-Directional) transceiver to break this rule. What's BiDi transceiver? How does it work? And why people believe it will have broad market prospect? This tutorial will give you the answer.

    What's BiDi Transceiver?

    BiDi transceiver is a type of fiber optic transceivers 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 used in pairs.

    How Does BiDi Transceiver 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 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 1310nmTransceiver B's diplexer must have a receiving wavelength of 1310nm and a transmit wavelength of 1550nm
    Diplexers at Work in BiDi Optical Ethernet Transceivers

    Advantages of BiDi Transceivers

    The obvious advantage of utilizing BiDi transceivers, such as SFP+- BiDi and 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 (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.

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  • 40G QSFP+ Transceiver Modules and DAC/AOC Cables Installation Guide

    To install and remove the transceiver optics in a right way is very necessary to ensure the network to work stably and efficiently. Today, we are going to introduce an installation guide of QSFP transceivers and DAC/AOC cables in 40G network.

    40GbE QSFP+ Transceivers Overview

    40 Gigabit Ethernet (40GbE) aggregation switches are becoming more common in today's data centers. At the heart of the 40GbE network layer is a pair of transceivers connected by a cable. The transceivers are plugged into either network servers or a variety of components including interface cards and switches and connected via the cables such as OM3 and OM4 for multimode application. Additionally DAC (Direct Attach Copper) cables or AOCs (Active Optical Cables) are used for short interconnection as a more cost-effective alternative solution. QSFP+ (Quad Small Form-factor Pluggable Plus) is the most common 40GbE interface type, and also as a high-density 10GbE interface via QSFP+ breakout cables. QSFP+ interfaces a network device (switch, router, media converter or similar device) to a fiber optic or copper cable, supporting data rates from 4x10 Gbps and supports Ethernet, Fibre Channel, InfiniBand and SONET/SDH standards with different data rate options. Compared to CFP (C form-factor pluggable) transceiver modules, QSFP transceiver modules are more compact and more suitable for port-density application. The two basic interface specifications of QSFP+ modules respectively for multimode and single-mode applications are 40GBASE-SR4 and 40GBASE-LR4.

    40GBASE-SR4 QSFP+ Module

    The 40GBASE-SR4 QSFP+ module, conforming to the 802.3ba D3.2 (40GBASE-SR4) standard, provides a 40Gbps optical connection using MPO/MTP® optical connectors. This optical module integrates four data lanes in each direction with 40Gbps aggregate bandwidth and each lane can operate at 10.3125 Gbps. It is used in data centers to interconnect two Ethernet switches with 8 fiber parallel multimode fiber OM3/OM4 cables (transmission distance can be up to 100 meters using OM3 fiber or up to 150 meters using OM4 fiber).

     

    40GBASE-LR4 QSFP+ Module

    The 40GBBASE-LR4 QSFP+ module, conforming to the 802.3ba (40GBASE-LR4) standard, provides a 40Gbps optical connection using LC optical connectors. This optical module integrates four data lanes in each direction with 40Gbps aggregate bandwidth and each lane can operate at 10.3125 Gbps. It is most commonly deployed between data center or IXP sites with single-mode fiber up to 10 km.

     In addition, to satisfy a number of different objectives including support for MMF and SMF compatibility, there are other types of QSFP+ modules offered by different vendors.

    How to Install/Remove QSFP+ Transceivers and DAC/AOC Cables
     
    Preparations

    To protect a QSFP+ module or cable from ESD (electro-static discharge) damage, before installing or removing a QSFP+ module or cable, be remembered that always wear an ESD wrist strap and make sure that it makes good skin contact and is securely grounded (If you are using ESD gloves, wear the wrist strap outside the ESD glove).

    To Install or Remove a QSFP+ Transceiver Module

    There are two types of clasp designed for a QSFP+ transceiver module—plastic clasp or a metallic clasp. Here uses the metallic clasp type as an example.

    To Install a QSFP+ Transceiver Module

    Step 1. Remove the QSFP+ module from its antistatic container and remove the dust covers from the module optical connector.
    Step 2. Remove any rubber dust covers from the port where you are installing the QSFP+ module.
    Step 3. Pivot the clasp of the module up. (Skip this step if the clasp is plastic.)
    Step 4. Align the module with the port in the chassis, as shown in Figure 1.

    Figure 1. Aligning the module with the port
    Figure 1. Aligning the module with the port

    Step 5. Holding the module, gently push in the module until it is firmly seated in the port.(see Figure 2.)

    Figure 2. Install the QSFP+ module to port
    Figure 2. Install the QSFP+ module to port

    Step 6. Immediately attach the patch cord with MPO connector or duplex LC connector to the QSFP+ transceiver module.(see Figure 3.)

    Figure 3. Install the patch cord to the module
    Figure 3. Install the patch cord to the module

    Note: Install the dust plug for the transceiver module if you are not to install an optical fiber into it.

    To Remove a QSFP+ Transceiver Module

    Step 1. Remove the optical fiber if any.
    Step 2. Pivot the clasp of the module down to the horizontal position. (Skip this step if the clasp is plastic.)
    Step 3. Holding the module, gently pull the module out of the port. (Figure 4)
    Step 4. Place the QSFP+ transceiver into an antistatic bag.

    Figure 4. Remove the QSFP+ module
    Figure 4. Remove the QSFP+ module

    To Install or Remove a 40G QSFP+ Cable

    The installation and removal procedures are the same for QSFP+ DAC cables and QSFP+ AOC cables. Here uses a QSFP+ DAC cable as an example:

    To Install a QSFP+ DAC Cable

    Step 1. Align the QSFP+ transceiver module (with the clasp on top) at one end of the cable with the port in the chassis, as shown in Figure 5.
    Step 2. Horizontally and gently push in the module to fully seat it in the port.

    Figure 5. Installing a QSFP+ DAC cable
    Figure 5. Installing a QSFP+ DAC cable

    To remove a QSFP+ DAC Cable

    Step 1. Gently press and release the QSFP+ transceiver module.(see Figure 6.)
    Step 2. Holding the cable, gently pull the clasp on the cable to pull out the transceiver module.

    Figure 6. Removing a QSFP+ DAC cable
    Figure 6. Removing a QSFP+ DAC cable

    To Install or Remove a 40G QSFP+ to 4x10G SFP+ Cable

    40G QSFP+ to 4x10G SFP+ cable combines one 40G QSFP+ module on one end and four 10G SFP+ module on the other end. The installation and removal procedures of 40G QSFP+ connector are introdueced above. Here only introduced the installation and removal of 10G SFP+ module:

    To Install an SFP+ Transceiver Module

    Step 1. Align the module with the SFP+ port, with the golden plating facing the spring tab (see Figure 7.) in the SFP+ port. If the chassis has two rows of ports, the spring tab in a port is on the bottom in the upper row and on the top in the lower row.
    Step 2. Slightly press the module against the spring tab so you can push the module straight into the port.

    Figure 7. Installing an SFP+ transceiver module
    Figure 7. Installing an SFP+ transceiver module

    To Remove an SFP+ Transceiver Module

    Step 1. Press the module with your thumb, as shown by callout 1 in Figure 8.
    Step 2. Gently pull the clasp on the cable to pull out the transceiver module, as shown by callout 2 in Figure 8.

    Figure 8. Removing an SFP+ transceiver module
    Figure 8. Removing an SFP+ transceiver module

    Verifying the installation

    Execute the display transceiver interface command on the device to verify that the transceiver module or DAC/AOC cable is installed correctly. If the transceiver module and DAC/AOC cable information is displayed correctly, the installation is correct. If an error message is displayed, the installation is incorrect or the transceiver optics is not compatible.

    transceiver interface command

    Conclusion

    As 40 GbE are widely deployed, 40G transceiver optics are ubiquitous. A good practice and correct installation are very important for 40G network system, not only to protect the 40G transceiver optics and device from damage, but also to ensure a stable performance for system. In addition, by executing the display transceiver interface command, we can verify whether the installation is correct. Of course, the premise is that the transceiver optics you use is fully compatible with your device. COMPUFOX offers a comprehensive line of high-compatible 40G transceiver optics, such as 40GBASE-SR4 QSFP+, 40GBASE-LR4 QSFP+ and 40G DACs and AOCs with competitive prices. See Links below:

     

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