Category Archives: Fiber Optical Transceivers

Will Single-mode Fiber Work Over Multimode SFP Transceiver?

Network installers usually come across a situation that device you have in your network does not always fit and work perfectly with the fiber. They plan to make a cable plant based on the multimode cabling, but owing to the link limitation or other reasons, they have to connect multimode equipment with single-mode devices. Is it feasible? Or put it more specifically, can I use the multimode SFP over single-mode fibers or vice versa? This article will give you a detailed illustration about the feasibility of the solutions, and introduce two relevant devices (mode conditioning cable and multimode to single-mode fiber media converter).

Single-mode Fiber Over Multimode SFP—You Can If You Are Lucky

This is the question that has been asked so many time, but no one can give the exact answer—yes or no. Hence, let’s illustrate it in details.

Most people think single-mode and multimode fibers are not interchangable because of the wave length of the laser and core size of the fiber. Single-mode fiber (MMF) uses a laser as a light source (the light beam is very concentrated), while multimode fiber (MMF) uses an LED to generate the signal. This would require two significantly different devices to generate the signal.

The core sizes are drastically different between SMF and MMF. SMF is 9 micron and multimode is 62.5 or 50 micron. If users try to mix the single-mode and multimode cabling in the same network, they might have trouble dealing with the two different types of signal.

However, it is possible to interconnect two devices using SMF interfaces at one end and MMF receiver at the other end. Keep in mind that it depends on the devices, so you can if you are lucky. When plugging LC single-mode duplex fibers on the multimode fiber transceiver (1000GBASE-SX) in the network, you will find the link came up (the light on the switch turns green). Therefore, the multimode fiber transceiver connected by the single-mode fibers works for short-reach application. The following image is the real screenshot of the single-mode fibers inserting into the 1000BASE-SX SFP.

real screenshot of inserting single-mode fiber over multimode fiber transceivers

While it should be stressed that the link is not reliable and it only works for particular brand devices with a very short link length. Many sophisticated vendors like Huawei, Alcatel or Cisco do not support it. Nevertheless, owing to the differential mode delay (DMD) effect, signal loss of this connection is not acceptable, either.

To sum up, this might be feasible but not advisable. If you need to make a connection between single-mode and multimode interfaces, you’d better use the intermediate switch that is able to convert the signals between single-mode and multimode fibers. The following part will introduce two solutions that might be helpful for the multimode and single-mode conversion.

Solution 1: MCP Cable—Single-mode In and Multimode Out

As to the multimode fiber with single-mode SFPs, most people mention the mode conditioning patch (MCP) cables. The MCP cable is launched to support 1000BASE-LX optics over multimode cable plant. The mode conditioning cables allow customers to successfully run Gigabit Ethernet over our multimode cable using single-mode fiber transceivers, Cisco 1000BASE-LX/LH SFP is the special type of transceiver that can both support single-mode and multimode fibers. The image below displays the difference between standard SC multimode patch cable and SC mode conditioning patch cable.

comparison between standard SC multimode fiber patch cable and SC MCP cable

Then, in this situation, you can run successfully from a single-mode fiber transceiver over multimode fiber with the use of MCP cables, but the distance will not exceed the link specification for multimode transceivers. Otherwise, there will be much signal loss in the cable run.

In general, if you want to run multimode fiber optic cable over 1000BASE-LX SFPs, you can use the mode conditioning cable. However, mode conditioning patch cords are required for link distances greater than 984 feet (300 meters). For distance less than 300 m, please omit the mode conditioning patch cords (although there is no problem using it on short links).

Solution 2: Fiber to Fiber Media Converter—Conversion Between Multimode and Single-mode Fibers

As noted before, mode conditioning cables, to some extent, can realize the connection between single-mode to multimode, but you can not say that you can convert single-mode to multimode or vice versa. Mode conversion between multimode and single-mode fibers often requires fiber to fiber media converters or the single-mode to multimode fiber converter.

F2F-10G-Multimode-to-Single-mode

In the above diagram, two Ethernet switches equipped with multimode fiber ports are connected utilizing a pair of fiber-to-fiber converters which convert the multimode fiber to single-mode and enable network connectivity across the distance between Gigabit switches.

Conclusion

It doesn’t really make much sense to use the single-mode fiber transceivers with multimode fibers in your network or vice versa, although the link will come up. Like I said above, you can if you are lucky connect. MCP cables and fiber to fiber converter are the two available options for single-mode and multimode connection. If you bought the wrong fiber optic cables, just replace it into the right one. Fiber optic cables and optical transceivers modules nowadays are very cheap. You won’t need to risk of mixing them in the same network.

Original Source : Single-mode Fiber Work Over Multimode SFP Transceiver

QSFP+ to SFP+ Adapter (QSA) Module Vs. QSFP+ to SFP+ Breakout Cable

People frequently ask about feasible solutions between 10G and 40G servers. QSFP+ breakout cables like QSFP+ to 4 SFP+ cables and MTP to 4 LC harness cables are the commonly used equipment to connect between QSFP+ ports and SFP+ ports. But recently, Cisco launched a new type of product—QSFP+ to SFP+ Adapter (QSA) module that could provide a smooth migration to 40 Gigabit Ethernet. Is it a better solution for the 10G to 40G migration? Should I use the QSA module or 40G QSFP+ breakout cable? This article will answer the above questions and provide some suggestions to you.

QSA Module—Is It a Better Solution for the 40G Migration?

The QSFP+ to SFP+ Adapter module, specified by Cisco, is the module built in QSFP+ form factor with a receptacle for SFP+ cable connector at the back (seen in the below image). When connecting the QSFP port to an SFP+ port, QSA module usually acts as an interface for SFP+/SFP cables. That means you can effectively plug in an SFP+/SFP optics operating at a 10 Gbps port on this module, then inserting the module into a QSFP port cage to realize the 40G Ethernet transition. QSFP+ to SFP+ adapter module ensures the smooth connectivity between 40 Gigabit Ethernet adapter and 10 Gigabit hardware using SFP+ based cabling. Therefore, once the QSA module came out in 2016, it was soon considered as the effective solutions for converting 40G ports to the 10G ports.

Cisco QSFP+ to SFP+ adapter cable

40G QSFP+ Breakout Cables Overview

People usually use either the QSFP+ to 4 SFP+ breakout cables or MTP to LC harness cables to convert the downlink 40G port of ToR (Top of Rack) access layer switch into 4x10G fan out mode, then connect to the 10G cabinet server port. QSFP+ to SFP+ breakout cable including the direct attach copper cable (DAC) and active optical cable (AOC) consists of a QSFP+ connector on one end and four SFP+ connectors on the other end. The cables use high-performance integrated duplex serial data links for bidirectional communication on four links simultaneously.

QSFP+ to SFP+ breakout cable

While the MTP to LC harness cable have one one MTP cables on the one end and four LC connectors on the other end. This type of cable is recommended to be used in the same rack within the short distance. The picture above shows the direct connectivity between the QSFP+ transceivers and SFP+ transceivers by using the MTP to LC harness cable.

QSA Module or QSFP+ Breakout Cable

In this part, I will make a comparison between QSFP+ to SFP+ adapter modules and QSFP+ breakout cables from the aspects of cost, performance and compatibility.

Cost—QSFP+ Breakout Cables Wins

QSFP+ to SFP+ adapter module is not certificated by Multi-source Agreement (MSA), but a sole source paradigm defined by few vendors. The only vendor owns its patent, so the QSA modules on the market are quite expensive. Nevertheless, QSFP+ breakout cables covered in the MSA standard, support both copper and optical connectivity, which are much cheaper than QSA modules. Cost comparison between QSA module and QSFP+ breakout cable (DAC, 1m) is listed in the below table.

cost comparison between QSA module and QSFP+ breakout cable

Performance

With QSA module, users have the flexibility to use any SFP+/SFP optics to connect to the 40Gbps data rate with a single 10G connection. However, QSA module only exists in 10G-40G speed, which also explains the reasons of its unpopularity of the market. QSFP+ to 4 SFP+ breakout cables split the 40G channel into 4x10G channel which provide four times more data transfers than QSA module does.

Compatible Switch and SFP/SFP+ Modules

QSA modules, according to Cisco, are available in 40 Gigabit Ethernet compatibility matrix. Cisco SFP/SFP+ transceivers that can be plugged into the QSA modules are concluded as Cisco 10GBASE-SR, LR, ER, ZR, DWDM SFP+, FET-10G and 10G SFP+ cable as well as SFP (1000BASE-T, SX, LX, EX, ZX). As for the QSFP+ to SFP+ breakout cables, different vendors have different compatible issues. Keep in mind that you should find the reliable fiber optic transceiver manufacturers.

Reminder:

  • Before using the QSA modules or the QSFP+ breakout cables to connect a 40 Gigabit Ethernet port to a 10 Gigabit SFP+ port, you must enable the fan-out mode of your devices.
  • Not all the 40G cards and switches can be split into 4x 10Gb mode, for example, the Mellanox QSFP cards do not support the QSFP to SFP+ breakout, but their switches can.
  • With the QSA module, you can directly use the SFP+ modules in a QSFP+ port, but you cannot use the QSFP+ optical cables in a QSA setup.
  • Telecom industry has been modified rapidly. Hence, it is more cost-effective to make additional investment in high-speed switches instead of breakout cables and expensive QSA modules.
Conclusion

Both the QSFP+ breakout cables and QSA modules provide a smooth migration to the 40 Gigabit Ethernet. With these optics, you can reuse the existing 10G SFP+ cables, optical transceivers and switches when upgrading to 40G Ethernet. QSFP+ breakout cables is regarded as the cost-effective and reliable solutions for the most situations, but QSA module is preferable for the application with a single 10G connection.

Can I Use the QSFP+ Optics on QSFP28 Port?

100G Ethernet will have a larger share of network equipment market in 2017, according to Infonetics Research. But we can’t neglect the fact that 100G technology and relevant optics are still under development. Users who plan to layout 100G network for long-hual infrastructures usually met some problems. For example, currently, the qsfp28 optics on the market can only support up to 10 km (QSFP28 100GBASE-LR4) with WDM technology, which means you have to buy the extra expensive WDM devices. For applications beyond 10km, QSFP28 optical transceivers cannot reach it. Therefore, users have to use 40G QSFP+ optics on 100G switches. But here comes a problem, can I use the QSFP+ optics on the QSFP28 port of the 100G switch? If this is okay, can I use the QSFP28 modules on the QSFP+ port? This article discusses the feasibility of this solution and provides a foundational guidance of how to configure the 100G switches.

For Most Switches, QSFP+ Can Be Used on QSFP28 Port

As we all know that QSFP28 transceivers have the same form factor as the QSFP optical transceiver. The former has just 4 electrical lanes that can be used as a 4x10GbE, 4x25GbE, while the latter supports 40G ( 4x10G). So from all of this information, a QSFP28 module breaks out into either 4x25G or 4x10G lanes, which depends on the transceiver used. This is the same case with the SFP28 transceivers that accept SFP+ transceivers and run at the lower 10G speed.

QSFP+ can work on the QSFP28 ports

A 100G QSFP28 port can generally take either a QSFP+ or QSFP28 optics. If the QSFP28 optics support 25G lanes, then it can operate 4x25G breakout, 2x50G breakout or 1x100G (no breakout). The QSFP+ optic supports 10G lanes, so it can run 4x10GE or 1x40GE. If you use the QSFP transceivers in QSFP28 port, keep in mind that you have both single-mode and multimode (SR/LR) optical transceivers and twinax/AOC options that are available.

In all Cases, QSFP28 Optics Cannot Be Used on QSFP+ Port

SFP+ can’t auto-negotiate to support SFP module, similarly QSFP28 modules can not be used on the QSFP port, either. There is the rule about mixing optical transceivers with different speed—it basically comes down to the optic and the port, vice versa. Both ends of the two modules have to match and form factor needs to match as well. Additionally, port speed needs to be equal or greater than the optic used.

How to Configure 100G Switch

For those who are not familiar with how to do the port configuration, you can have a look at the following part.

  • How do you change 100G QSFP ports to support QSFP+ 40GbE transceivers?

Configure the desired speed as 40G:
(config)# interface Ethernet1/1
(config-if-Et1/1)# speed forced 40gfull

  • How do you change 100G QSFP ports to support 4x10GbE mode using a QSFP+ transceiver?

Configure the desired speed as 10G:
(config)# interface Ethernet1/1 – 4
(config-if-Et1/1-4)# speed forced 10000full

  • How do you change 100G QSFP ports from 100GbE mode to 4x25G mode?

Configure the desired speed as 25G:
(config)# interface Ethernet1/1 – 4
(config-if-Et1/1-4)# speed forced 25gfull

  • How do you change 100G QSFP ports back to the default mode?

Configure the port to default mode:
(config)# interface Ethernet1/1-4
(config-if-Et1/1)# no speed

Note that if you have no experience in port configuration, it is advisable for you to consult your switch vendor in advance.

Conclusion

To sum up, QSFP+ modules can be used on the QSFP28 ports, but QSFP28 transceivers cannot transmit 100Gbps on the QSFP+ port. When using the QSFP optics on the QSFP28 port, don’t forget to configure your switch (follow the above instructions). To make sure the smooth network transmission, you need to ensure the connectors on both ends are the same and no manufacturer compatibility issue exists.

100G QSFP28 PSM4 to Address 500m Links in Data Center

100G QSFP28 PSM4 optics is a type of 100G optical transceiver that provides a low-cost solution to long-reach data center optical interconnects. 100G PSM4 (parallel single-mode 4 lane) standard is mainly targeted to data centers that based on a parallel single-mode infrastructure for a link length of 500 m. Compared with the hot-selling 100GBASE-SR4 and 100GBASE-LR4 optics, 100G QSFP28 PSM4 recently wins the popularity among the overall users. This article will provide a complete specification of the 100G QSFP28 PSM4 transceiver and explain the reason why people would need QSFP28 PSM4.

QSFP28 module

QSFP28 PSM4—A Low-Cost but Long-Reach Solution

100G QSFP28 PSM4 is compliant with 100G PSM4 MSA standard, which defines a point-to-point 100 Gb/s link over eight parallel single-mode fibers (4 transmit and 4 receive) up to at least 500 m. PSM4 uses four identical lanes per direction. Each lane carries a 25G optical transmission. The 100G PSM4 standard is now available in QSFP28 and CFP4 form factor. Table 2 shows the diagram of the 100G QSFP28 PSM4 Specification. 100G PSM4 is a low-cost solution. Its cost structure is driven by the cost of the fiber and the high component count. FS.COM offers the Cisco compatible 100G QSFP28 PSM4 at US$750.00.

diagram of QSFP28 PSM4

As you can see in the above image, 100G QSFP28 PSM4 transceiver uses four parallel fibers (lanes) operating in each direction, with transmission distance up to 500 meters. The source of the QSFP28 PSM4 module is a single uncooled distributed feedback (DFB) laser operating at 1310 nm. It needs either a directly modulated DFB laser (DML) or an external modulator for each fiber. The 100GBASE-PSM4 transceiver usually needs the single-mode ribbon cable with an MTP/MPO connector.

Why Do We Need 100G QSFP28 PSM4?

100G PSM4 is the 100G standard that has been launched by multi-source agreement (MSA) to enable 500m links in data center optical interconnects. But as we all know, there are several popular 100G interfaces out there on the market, such as QSFP28 100GBASE-SR4, QSFP28 100GBASE-LR4, QSFP28 100GBASE-CWDM4, and CFP 100GBASE-LR4, etc. So with so many options, why do we still need 100G QSFP28 PSM4?

To better help you make up your mind, you need to figure out the following questions:

Q1: What are the net link budget differences between PSM4, SR4, LR4 and CWDM?
Table 3 displays the detailed information about these 100G standards.

100GBASE-PSM4 100GBASE-CWDM4 100GBASE-SR4 100GBASE-LR4
4-wavelength CWDM multiplexer and demultiplexer No need Need No need Need
Connector MPO/MTP connector Two LC connectors MPO/MTP connector Two LC connectors
Reach 500 m 2 km 100 m 10 km

Note: the above diagram excludes the actual loss of each link (it is the ideal situation). In fact, WDM solution are at least 7 db worse link budget than PSM4. For a 2 km connectivity, a CWDM module will have to overcome about 10 db additional losses compared to PSM4. And the 100G LR4 optics at 10 km is 12 db higher total loss than PSM4.

Q2: What power targets are achievable for each, and by extension what form factors?
According to the IEEE data sheet, the WDM solutions cannot reasonably fit inside QSFP thermal envelop, while PSM4 can fit inside the QSFP thermal envelope. That means you would need the extra power for the WDM solution of your network. But if you use the QSFP PSM4, this won’t be a problem.

All in all, a 100G QSFP28 PSM4 transceiver with 500m max reach is a optional choice for customers. Because other 100G optics are either too short for practical application in data center or too long and costly. QSFP28 PSM4 modules are much less expensive than the 10 km, 100GBASE-LR4 module, and support longer distance than 100GBASE-SR4 QSFP28.

Summary

QSFP28 PSM4 is the lowest cost solution at under one forth the cost of either WDM alternatives. 100G QSFP28 PSM4 can support a link length of 500 m, which is sufficient for data center interconnect applications. 100G QSFP28 PSM4 also offers the simplest architecture, the most streamlined data path, higher reliability, an easy upgrade path to 100G Ethernet.

How to Clean a Fiber Optic Transceiver?

To ensure the high performance of optical data transmission, fiber optic cleaning is regarded as an essential way to get rid of the contaminants on devices. Fiber optic connectors are often recommended to be cleaned on a regular basis. Apart from the connectors, other devices such as fiber optic transceiver, optical adapter should also be cleaned when they are being polluted. This post will focus on introducing the proper method of cleaning fiber optic transceivers.

How to Find a Contaminated Optical Transceiver?

Compared with connectors, transceiver modules seem to have a smaller chance to be contaminated. Therefore, fiber optic transceivers should only be cleaned when problems occur. Generally, if signal output from the transceiver is still false or in low-power after cleaning the connectors, you can clean the fiber optic transceiver instead to solve the issue. Common contaminant in optical transceivers is the debris or particles coming through the contact with optical connector ferrules. The following picture shows the comparison of dirty and clean interfaces of transceivers under the digital microscope.

fiber optic transceiver contaminants

Cleaning Tools

Air duster and lint-free swab are the major cleaning tools for fiber optic transceivers. Air duster uses the clean dry air to blow any dust and debris out of the transceiver. Lint-free swab is special for not leaving any lint in the transceiver interface after cleaning.

cleaning tools

Things to Note Before Cleaning

A safe operation is very important to protect yourself from unnecessary accidents. Before starting the cleaning process, here are some precautions for you to note.

  • Always handle optical modules in an ESD (electro-static discharge) safe area using the proper safety precautions.
  • Ensure that the module power is off and handle the modules with care.
  • Always use CDA or an approved canned compressed air supply.
  • Always hold the can of compressed air upright. Tipping may release liquids in the air stream.
  • Do not touch the inner surfaces of the module including the OSA (optical subassemblies), or insert any foreign objects into the ports.
  • Use of finger cots or powder free surgical gloves is not required but can ensure better cleanliness.
Cleaning Procedures

After every thing is ready, you can start to clean the transceiver interface. The followings are the general cleaning steps for reference. If condition permits, you can use microscope to inspect the transceiver to ensure cleanliness. Usually, when output signal becomes normal, then the cleaning procedure is a success.

  • Step 1: Open the dust cover or remove the dust plug from the module.
  • Step 2: Use a non-abrasive cleaner (air duster) to remove any dirt or debris.
  • Step 3: Insert a lint-free cleaning stick of the appropriate size (2.5 mm or 1.25 mm) and turn clockwise. It is recommended to do dry cleaning instead of wet cleaning by using alcohol-based cleaning sticks.
  • Step 4: Repeat steps 2 and 3 if necessary.
  • Step 5: Remove the cleaning stick, and reinsert the module’s dust cap. Always keep the dust cap inserted in the module when not in use.
  • Step 6: Always make sure that the connector is also clean before plugged into the module.
Conclusion

Fiber optic cleaning plays an important role in fiber optic system. Although optical transceivers are less frequent to be cleaned, the request for cleaning still exists. As long as you use the correct cleaning tools and follow the right cleaning procedures, transceivers can surely be cleaned with no more contamination. In this case, the efficiency of fiber optic system will be greatly improved.

Getting to Know About DWDM Tunable Transceiver

DWDM (Dense Wavelength Division Multiplexing) technology offers a great way to boost channel capacity and transmission speed for optical systems. And it has been used in many applications, especially in long haul transmissions. In these applications, DWDM optic transceiver plays an important role. This post intends to introduce a special kind of DWDM transceiver—tunable transceiver.

What Is a DWDM Tunable Transceiver?

DWDM tunable transceiver is a unique transceiver that can select the channel or “color” the laser emits. Put it in simple terms, most WDM systems generally use optical transceivers with a fixed wavelength. That means there is a spare for each wavelength in use. But tunable transceiver has the capacity to adjust the wavelength of the transceiver on-site to meet different requirements. That’s the most distinguished point of tunable transceivers. Another characteristic of tunable transceivers is that the tunable function only lies in DWDM system due to the dense wavelength grid of DWDM.

Typically the tunable transceivers are for the C-band 50GHz. Around 88 different channels can be set with intervals of 0.4nm, which is the 50GHz band. These optics usually start from channel 16 up to 61 but this depends on the manufacturer’s router/switch and which channels it supports. And the transmission distance of DWDM tunable transceiver over single mode fibers is up to 80km and data speed is up to 10Gbps.

In addition, the DWDM tunable transceivers are available for a wide range of equipment like routers, switches and servers. With these transceivers, network operators can change wavelengths unlimited within the C-band DWDM ITU grid.

Types of DWDM Tunable Transceiver

In today’s market, there are mainly two kinds of DWDM tunable transceivers.

Tunable XFP transceiver

Tunable XFP transceiver are manufactured with an integrated full C-band tunable transmitter and a high performance receiver. Wavelengths can be set as default in 50GH DWDM ITU grid. The maximum distance of this transceiver on a single mode fiber is up to 80km. In the market, different manufactures may name tunable XFP transceiver in different forms. For example, Cisco may name it as “ONS-XC-10G-C” while Juniper version is “XFP-10G-CBAND-T50-ZR”. Besides, this transceiver be tuned in different ways.

10g dwdm tunable xfp transceiver

Tunable SFP+ Transceiver

The tunable SFP+ optical transceiver is a full duplex serial electric, serial optical device. Its transmit and receive functions are contained in a single module that provides a high-speed serial link at 9.95 to 11.3Gbps signaling rates. And the transceiver supports the enhanced SFP+ specification. Here is a simple picture showing its working process.

SFP plus tunable transceiver

On the transmit side, the serial data are passed from the electrical connector to a modulator driver. The modulator driver modulates a C-band cooled tunable transmitter, enabling data transmission over up to 80km on single mode fiber through an industry standard LC connector. On the receive side, the 10G optical data stream is recovered from an APD through a transimpedance amplifier to the electrical connector.

Benefits of DWDM Tunable Transceiver

Tunable transceivers have progressed rapidly in recent years. They have become popular in DWDM transmission systems because of their multi-faceted abilities and ease of spare use. Especially when combined with ROADM (reconfigurable optical add-drop multiplexers), DWDM tunable transceivers become a powerful transmission component. In simple terms, DWDM tunable transceivers have benefits below.

  • A wide tuning range. Compared with common fixed wavelength optical transceivers, DWDM tunable transceivers can save time and money in the long run.
  • Be more suitable for 100G systems by reducing line-width. The ability to adjust wavelengths provides more convenience to fit different transmitting needs.
  • Tunable lasers are capable of switching wavelengths in just nanoseconds. Tunable laser is a vital part of tunable transceivers. It is a high-speed and high-performance optics, enabling the needed wavelength to be reprogrammed in seconds.
Summary

DWDM tunable transceivers are able to function on various wavelengths and to adjust wavelengths according to users’ needs, making them prevalent among DWDM systems. This article mainly introduces the basis and two types of DWDM tunable transceivers. If you want to know more about it, please visit FS.COM.

Things You Need to Know About DWDM Transceiver

In optical communications, DWDM (Dense Wavelength Division Multiplexing) technology enables a number of different wavelengths to be transmitted on a single fiber, which makes it a popular choice among many different areas such as local area networks (LANs), long-haul backbone networks and residential access networks. In these transmission processes, DWDM transceivers play an important role. Here is a brief introduction to them.

Basics of DWDM Transceiver

DWDM transceiver, as its name shows, is a kind of fiber optic transceiver based on DWDM technology. As mentioned above, it enables different wavelengths to multiplex several optical signals on a single fiber without requiring any power to operate. And these transceivers are designed for high-capacity and long-distance transmissions, supporting to 10 Gbps and spanning a distance up to 120 km. Meanwhile, the DWDM transceivers are designed to Multi-Source Agreement (MSA) standards in order to ensure broad network equipment compatibility.

The basic function of DWDM transceiver is to convert the electrical signal to optical and then to electrical signal, which is as same as other optical transceivers. However, based on DWDM technology, DWDM transceiver has its own features and functions. It’s intended for single-mode fiber and operate at a nominal DWDM wavelength from 1528.38 to 1563.86 nm (Channel 17 to Channel 61) as specified by the ITU-T. And it is widely deployed in the DWDM networking equipment in metropolitan access and core networks.

Common Types of DWDM Transceiver

There are different types of DWDM transceiver according to different packages such as DWDM SFP transceiver, DWDM SFP+ transceiver, DWDM XFP transceiver, DWDM XENPAK transceiver and DWDM X2 transceiver. Here is a simple introduction to them.

DWDM SFP Transceiver

DWDM SFP transceiver is based on the SFP form factor which is an MSA standard build. This transceiver provides a signal rate range from 100 Mbps to 2.5 Gbps. Besides, DWDM SFP transceiver meets the requirements of the IEE802.3 Gigabit Ethernet standard and ANSI fibre channel specifications, and are suitable for interconnections in Gigabit Ethernet and fibre channel environments.

dwdm-sfp

DWDM SFP+ Transceiver

DWDM SFP+ transceiver, based on the SFP form factor, is designed for carriers and large enterprises that require a flexible and cost-effective system for multiplexing and transporting high-speed data, storage, voice and video applications. The maximum speed of this transceiver is 11.25G. It’s known to all that DWDM enables service providers to accommodate hundreds of aggregated services of sub-rate protocol without installing additional dark fiber. Therefore, DWDM SFP+ transceiver is a good choice for 10G highest bandwidth application.

dwdm-sfp-plus

DWDM X2 Transceiver

DWDM X2 Transceiver is a high performance serial optical transponder module for high-speed 10G data transmission applications. The module is fully compliant to IEEE 802.3ae standard for Ethernet, which makes it ideally suitable for 10G rack-to-rack applications.

dwdm-x2

DWDM XFP Transceiver

DWDM XFP transceiver is based on the XFP form factor which is also an MSA standard build. The maximum speed of this transceiver is 11.25G and it is usually used in 10G Ethernet. This transceiver emits a specific light. And there are different industry standards and the 100Ghz C-band is the most used one which has a spacing of 0.8 nm. What’s more, DWDM XFP supports SONET/SDH, 10GbE and 10 Gigabit fibre channel applications.

dwdm-xfp

DWDM XENPAK Transceiver

DWDM XENPAK transceiver is SC duplex receptacle module and is designed for backbone Ethernet transmission systems. It is the first 10GbE transceiver ever to support DWDM. And it can support 32 different channels for transmission distance up to 200 km with the aid of EDFAs. DWDM XENPAK transceiver allows enterprise companies and service providers to provide scalable and easy-to-deploy 10 Gigabit Ethernet services in their networks.

dwdm-xenpak

Applications of DWDM Transceiver

As the growing demand of bandwidth, DWDM technology is becoming more and more popular. And DWDM transceivers are commonly used in MANs (metropolitan area networks) and LANs. Different types of DWDM transceiver have different applications. For example, DWDM SFP transceivers are applied in amplified DWDM networks, Fibre Channel, fast Ethernet, Gigabit Ethernet and other optical transmission systems, while DWDM XFP transceivers are usually used in the fields which meet the 10GBASE-ER/EW Ethernet, 1200-SM-LL-L 10G Fibre Channel, SONET OC-192 IR-2, SDH STM S-64.2b, SONET OC-192 IR-3, SDH STM S-64.3b and ITU-T G.709 standards.

Conclusion

In summary, DWDM transceiver is an essential component in DWDM systems. Fiberstore offers various DWDM transceivers and is able to provide the advanced technology and strong innovative capability to produce the best optical components for DWDM systems. If you are interested in our products, please visit FS.COM for more detailed information.

Suggestions for Solving Unsupported Transceiver Errors

The unsupported transceiver errors may arise at any time of your work. Though this situation is the least you want to see during work, you must be enough prepared to solve issues in time. To deal with the errors is now an essential part to keep good running of devices. And different vendors will have tips to solve errors for their own products. But are there any suggestions for general issues? The answer is yes. This article will give some advice for how to deal with unsupported transceiver errors on ordinary occasions.

Unsupported-Transceiver-Errors

Suggestions

1)Check the error message first before actually deal with the problem. Different ways to address the errors are depending on the message you receive. Here is an example, when you receive this message, “3750e-sw1(config)#service unsupported-transceiver [1]”, the error may result from the false customer installation or a defective product. Thus, error message is a good source to decide your next step.

2)An uncertified transceiver will cause errors under most cases. When the third-party device does not come from a channel partner, problems may also arise. It is not that easy to address router issues if the transceivers is required to be made from the same manufacturer. But specialists may turn to hack codes to solve the problem.

3)Hidden commands of some devices may also cause errors. The message will go like “service unsupported transceiver”. But it allows other transceivers as an option for you to decide whether the transceiver should be replaced.

4)Before removing the transceiver to solve a third-party error, you can look up other options first. Because sometimes the third-party transceiver can provide significant savings for you. Perhaps one of the savings will help settle the problem.

About Third-Party Transceivers

Although you may encounter the unsupported errors when using the third-party transceiver, it still has some advantages. The major benefit is the cost which is much lower than the cost of original transceivers. Since the cost of transceiver takes a huge part of the entire system cost, reducing the investment on transceiver can greatly save expenses for better designs.

Also, the compatibility of third-party transceivers has been greatly increased thanks to the fully specified international standards. The risk of incompatibility is much lower, and there is no need to worry about buying a transceiver from formal vendors. For instance, FS.COM is one of the reliable manufacturers that provides cost-effective third-party transceivers, and all of the transceivers are 100% compatible to any named brands like Cisco, Juniper, Arista and so on.

Conclusion

Anyway, in order to avoid unsuspected transceiver errors, the fundamental aim is to make sure that the transceiver completely complies with IEEE and MSA standards. Understanding the hidden commands can also help you find out the source of error. So long as you follow the above suggestions, most of the problems can be solved in a short time. The purpose of dealing with the errors is all about getting good results, and your working efficiency will also be improved if there is no problem with the devices.

Overview of Active Optical Cable

In respond to the demand for a higher data bandwidth, active optical cable (AOC) has came into being to satisfy different cloud computing applications. Active optical cable is a term used to describe a cable that mates with standard electrical interfaces. The electrical-to-optical conversion on the cable ends is adopted to enhance the transmission speed and distance of the cable without sacrificing compatibility of standard electrical interfaces. This article will give a general introduction of active optical cable and its most popular product in the current market.

Structure of Active Optical Cable

Active optical cable mainly consists of two parts- the fiber optic connector and fiber cable. The connection between fiber cable and connectors is not separable. If the connector or cable needs to be changed, they should be removed together. The electrical and optical signal conversion can be achieved right through each ends of optical fiber.

AOC-Structure

Advantages of Active Optical Cable

However, people may wonder the reasons why choosing active optical cable over direct attach copper cable. Here are some advantages of using active optical cable:

1) Although both cables are used for short range data communication, active optical cable is able to provide a longer reach than direct attach copper cable among devices.

2) Active optical cable has a higher bandwidth because its signal transmits through optical fiber as optical signal which transmits faster than electrical signal in copper cable. The maximum throughput is up to 40 Gbps with QSFP+.

3) The weight of active optical cable is lighter than copper cable due to the optical fiber material. It is possible to achieve a simpler cable management with a lower weight.

4) EMI (electromagnetic interference) immunity is another benefit of active optical fiber. EMI is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling or conduction. Since the optical fiber is a kind of dielectric which is unable to conduct electric current, active optical cable will not be affected by the electromagnetic energy.

Applications of Active Optical Cable

Active optical cable has been applied to different fields. The followings are the most typical applications for active optical cables:

1) Infiniband QDR, DDR and SDR interconnects

2) Data aggregation, backplane and proprietary density applications

3) PCI-Express, SAS/SATA, Fiber Channel compatible interconnect

4) 40GBE and 10GBE interconnects

5) 10G, 40G telecom connections

6) Hubs, switches, routers, servers

7) Ethernet 10G, 40G

8) Data centers

9) High performance computing clusters

Popularity of 40G Active Optical Cable

Nowadays 40G active optical cable has become one of the most popular products in the market. It is an active optical cable used for 40 GbE terminated with 40GBASE QSFP+. Particularly, 40G breakout active optical cables, such as 40GBASE QSFP+ to 4xSFP+ AOC or 40GBASE QSFP+ to 8xLC AOC, are cost-effective solutions for 40G to 10G migration.

Conclusion

Active optical cable has now taken a great share of the market and is still booming for further development. The interconnection in short range and high speed between devices makes it practical in data center. As the technology matures, the application of active optical cable will be migrated to higher speed transmission in the future.

Who is the Winner of 10G Transceivers?

10G transceivers refer to the optical modules which can transmit and receive the data signal of 10 gigabits per second. Typically, the fiber optic transceivers including XENPAK, X2, XFP and SFP+ (small form-factor pluggable plus) are widely used for 10 Gigabit Ethernet. But who is the winner among these transceivers? From the following introduction we may find some clues.

XENPAK Transceivers

The first published form-factor, the XENPAK, was by far the largest in physical size. This standard was driven primarily by large systems vendors and was intended to support essentially any optical application a system vendor may want to deploy. At the time this multi-source agreement (MSA) was published, 10Gbps optical interfaces supporting transmission distances of 80km or more were of a size and heat dissipation that required a relatively large (by today’s standards) package size.

XENPAK-Transceivers

X2 and XFP Transceivers

Many in the industry recognized the size of the XENPAK as very limiting factor and began working on alternative standards. Over the following two years three alternative MSAs were published, called: X2 and XFP. When these standards were written they were intended to enable optical interfaces supporting up to about 10 km. The X2 and XFP form-factors both saw considerable deployment. As optical technology has advanced over the last ten years, X2 and XFP modules have been developed that support all of the high-power, long-distance applications once reserved to the larger XENPAK transceivers.

X2-and-XFP-transceivers

SFP+ Transceivers

Five years after the first 10Gbps optical transceiver standard was issued, a new MSA was published called the “SFP+”. This agreement has been the basis for the most commercially successful 10Gbps optical transceivers by a large margin.

There are several reasons for the success of the SFP+ standard:

  • Flexibility The SFP+ standard builds on a previous one, the SFP MSA (primarily a 1Gbps standard). SFP+ modules are the same physical size as SFPs and the SFP+ standard allows for either type of module to operate in the new SFP+ slots.
  • Small Size SFP+ modules are one tenth the size of the original XENPAK 10G modules and are the same size as the popular 1Gbps SFP modules. This small size allows the design of systems with 10G ports of the same density as previous generations with 1G ports.
  • Low Cost Since SFP+ modules share many components (bezel, housing, latch/locking mechanism) on the previous SFP standard, the cost of the new 10G modules inherits the low cost of these components. SFP+ units are also lower power, contributing to cost savings

SFP-plus-transceiver

However, do you really know how to choose the right 10G form-factor? The following aspects should be taken into consideration:

Cost

When considering new or used equipment for a new network build or expansion, attention should definitely be given to the type of 10G ports in that equipment. One important reason is capital costs. Older gear offering XFP, X2 or XENPAK ports may be attractive due to what seems like very low prices. However, the cost of equivalent 10G optics in those older form factors is twice to three times the price of SFP+ based modules. Therefore, when the cost of the optics are included, total system costs may end up higher.

Power

The older XFP, X2 and especially XENPAK gear, both the host system and the 10GBase optical modules, consume considerably more power than the new SFP+ modules. Power costs include capital outlays for larger power/battery plant as well as operational cost of the electrical power itself.

Rack Space

Depending on the location, space in equipment racks can be quite expensive. Equipment utilizing the older 10Gbase interfaces is almost always substantially less dense, consuming more rack space per 10G interface available.

Conclusion

From the above, there is no doubt that SFP+ wins the battle. In consideration of the advantages in cost, size, power and flexibility of supportable optical interfaces, SFP+ is preferred among the 10G transceivers. So far, there has not been any new standard for 10G network due to a higher speed demand of Ethernet. Thus, SFP+ transceivers will remain to dominate the 10G transceiver market.