Fiber Optic Blog

As the quest for greater bandwidth continues and fibre optic connections within data centres and optic fibre networks increase, these challenges must be met by choosing the right type of connectivity. This is all driven by requirements for additional switching and routing, storage, virtualization, convergence, video-on-demand (VoD) and high performance cloud computing. All of these applications plus other bandwidth intensive applications increase the need for transmission speed and data volume over short distances.

Optic fibre 10G transmission systems are becoming more widely used and accepted and migration paths to 40G and 100G have been specified for optical fibre.

The IEEE 802.3ba 40G / 100G Ethernet standard provides guidance for 40G / 100G transmission with multimode fibre. OM3 and OM4 are the only multimode fibres included in the standard.

Parallel optics technology has become the transmission option of choice in many data centres and labs as it is able to support 10G, 40G, and 100G transmission. For parallel optics to work effectively, it requires the right choice of cable and connector.

Parallel optic interfaces differ from traditional fiber optic communication in that data is simultaneously transmitted and received over multiple optical fibres. In traditional (serial) optical communication, a transceiver on each end of the link contains one transmitter and one receiver. For example, on a duplex channel the transmitter on End A communicates with the receiver on End B and another optic fibre is connected between the transmitter on End B and the receiver on End A.

In parallel optical communication, the devices on either end of the link contain multiple transmitters and receivers, e.g. four transmitters on End A communicate with four receivers on End B. This spreads the data stream over the four optical fibres. This configuration would allow for the operation of a parallel optics transceiver which uses four 2.5 Gb/s transmitters to send one 10 Gb/s signal from A to B. In essence, parallel optical communication is using multiple paths to transmit a signal at a greater data rate than the individual electronics can support. This type of connectivity utilises a ribbon cable type design with all fibres aligned in a straight array, in either a 12 fibre or 24 fibre configuration.

In addition to the cable performance, the choice of physical connection interface is also important. Since parallel-optics technology requires data transmission across multiple fibres simultaneously, a multifibre connector is required. Factory terminated MPO / MTP connectors which have either 12 fibre or 24 fibre array, will support this solution. For example, a 10G system would utilise a single MPO / MTP (12 Fibre) connector between the 2 switches. Modules are placed on the end of the MPO connector to transition from a MPO connector to a 12 Fibre breakout LC duplex or SC duplex cable assembly. This enables connectivity to the switch. 40G and 100G systems require a slightly different configuration.

Utilising MPO / MTP connectivity has many benefits including:

High Density – multifibre connector and compact dimension of cable save space in costly data centre environments.

Reduces cable load in raised floors to existing active server/switch/storage equipment with LC Duplex interface (less cable OD, less connections.

Pre-connectorised solution, no splicing required on site.

Reliability -100% tested factory tested in a controlled environment

Latest active equipment by Cisco / IBM / HP /Sun Microsystems has the MPO-SFP connectivity interface for Gigabit Network transmission

Rapid Deployment – factory terminated modular system saves installation and reconfiguration time during moves, ads and changes.

Next Generation Network Proof – emerging high speed protocol are going to use MTP interface- your cabling infrastructure remains unchanged.

Difference between MPO and MTP connectors

From the outside there is very little noticeable difference between MPO and MTP connectors. Infact, they are completely compatible and inter-mateable. For example, an MTP trunk cable can plug into an MPO outlet and vice versa.

The main difference is in relation to its optical and mechanical performance. MTP is a registered trademark and design of UsConnec, and provides some advantages over a generic MPO connector. Since MPO / MTP optic fibre alignment is critical to ensure a precise connection there are some benefits in utilising the MTP connector. The MTP connector is a high performance MPO connector with multiple engineered product enhancements to improve optical and mechanical performance when compared to generic MPO connectors.

The MTP optic fibre connector has floating internal ferrule which allows two mated ferrules to maintain contact while under load. In addition, The MTP connector spring design maximizes ribbon clearance for twelve fibre and multifibre ribbon applications to prevent fibre damage.

Overall it provides a more reliable and precise connection.

In addition, it is also important when specifying an MPO/MTP system to ensure the correct polarity options and which cables and outlets have female or male pins.

In conclusion, three main factors must be considered are fiber optic cable type, fiber optic connector type and the switch port. In practical cabling, more should be considered. These three aspects are far from enough.

Wavelength-division multiplexing (WDM) is nothing new to us. It is a technology that multiplexes multiple optical signal on a single optical fiber by using different wavelengths of laser light. The multiple transmission paths involved in WDM network effectively relieve fiber exhaustion and extend link capacity, but they also make facility protection more essential than ever, because solid facility protection is the key to the availability of the link and the data being transmitted. This article introduces two methodologies that proven to be valid for optical link protection: electrical switching and optical switching.

Why Facility Protection is Essential to WDM Network?

With the explosion of information, the demand for extremely high-capacity data transmission began to soar. Enterprises and companies were asked to deliver greater volumes of traffic at much higher rates. Which spurs the need to store data in different facilities and to transport these data over different paths, so that if any network failure or downtime occurs, they can soon recover and keep the business running. In a properly protected WDM network, customers will have two or more sites that are connected to each other by diver paths, ensuring the availability and reliability of the network all the time. But fiber may break for many reasons including damage from the physical environment and human faults. Thus facility protection becomes vitally important.

Effective Facility Protection Methods for WDM Network

There are basically two methods for optical facility protection: one is electrical switching which adopts a cross connect to duplicate and select the working or protecting path, with two independent optics involved per each path and two Mux/Demux. And the other is optical switching, unlike electrical switching, it typically uses an optical switch to select the working or protected path.

Electrical Switching

In electrical switching, each service is simultaneously transmitted and received from two dark fibers. The signal from the device on the left side is transmitted to both working and protecting fiber, then it is delivered to the end device on the right side.

So how the cross connect duplicates the Tx signals and selects the working and protecting path (Rx) for the receiving signal? In fact, the Tx signal is sent through the cross connect and duplicated through both transponders. On the Rx direction, the cross connect switches the signal to the receiving optical power of the transponder.

Optical Switching

An optical switch is involved in this method to duplicate the data to the working and protecting fiber with an optical splitter, and selecting the operating fiber according to the optical power signals of all the services. One of the distinct differences between optical switching and electrical switching is that it simply offers no protection for the WDM optic.

Electrical Switching vs. Optical Switching: How to Choose?

When applied for optical facility protection, both methods have their benefits and drawbacks. For electrical switching, the WDM optic is better protected since it uses two uplink transponders per service – one for working and the other for protecting. Since protection is delivered per service, once a single service needs to be switched, the other service won’t be disturbed. Moreover, electrical switching is suited for any network topologies, and no power budget loss is associated with this method. However, electrical switching generally adopted more WDM optics and an additional Mux/Demux, hence fewer services are available through each unit, and it inevitably increases total costs.

While for optical switching which does not offer protection for WDM optic, more ports are available to transport services on each unit. Besides, no additional Mux/Demux is required in this method, so the overall cost of the solution can be decreased. The drawbacks of this method are that the optical switch lowers the optical power budget of the link. And optical switching is not suited for ring topologies for the fact that add and drop functionality is not available per wavelength.

Conclusion

Optical facility protection impacts the link availability, performance and reliability to a large extent. Your choice on facility protection method should always base on your specific needs, and taking power budget, network topology and cost into consideration. I hope this article would be helpful for you to make an informed decision.

Recently the building of QSFP-DD (Multi Source Agreement) Group has excited optical communication industry. This group, including 13 members which are all the leading vendors in the industry, like Cisco, Brocade and Finisar, aims to create a upgraded version of QSFP transceiver, which is called QSFP-DD ( double density QSFP) and will be able to support 200G/400G Ethernet.

Introduction

The QSFP-DD is similar to the current QSFP. But there are many differences between the current QSFP. The reason why the new transceiver is called “double density” is related to the current 100G QSFP28 transceivers. The “double density” means the doubling of the number of high-speed electrical interfaces that the module supports compare to regular QSFP28 module.

QSFP-DD and QSFP28

We can understand the QSFP-DD better by comparing it with the current 100G QSFP28 module. QSFP28 transceiver is a four-channel transceiver which is able to transmit and receive 100G per second simultaneously. With the advantages of high speed and low power, QSFP28 transceiver is becoming more popular than other 100G transceivers like CFP2 and CFP4. The 100G QSFP28 transceiver is implemented with four lanes with each supporting data rate of 25G.

The working principle of QSFP-DD is similar with 100G QSFP28 transceiver. The QSFP-DD MSA group will increase the lane to eight. There will be a row of contacts providing for an eight lane electrical interface in QSFP-DD. If modulated by NEZ, each lane of the QSFP-DD can support data rate up to 25G, thus, it can support a total data rate of 200G. If modulated by PAM4, it can support data rate up to 400G with each lane supporting data rate of 50G. The MSA group also announced that the QSFP-DD can enable up to 14.4Tbps aggregate bandwidth in a single switch slot, which can definitely satisfy the increasing need for higher bandwidth.

Another great feature of QSFP-DD is that its system will be backwards compatible, allowing them to support existing QSFP modules and provide flexibility for end users and system designer. This means the data center could save a considerable sum of money in the future upgrading.

Future and Present

The appearance of QSFP28 transceiver has changed the regular development road map of Ethernet. The regular upgrade road is 10G to 40G and then 100G. While the QSFP28 transceiver has changed it from 25G directly to 100G. The road map of this QSFP-DD is also drawing our attention. It is predicted that it will become a useful family of modules for the industry with application at greater than 400G. Meanwhile, there is no efforts underway to define these new speeds but it is expected that QSFP-DD will have a roadmap that supports.

Any way, no matter where the QSFP-DD lead our Ethernet to, it is good news for our future networking system. The creating of this new module will still need some time. For now, many data centers are considering about upgrading their data center with 100G QSFP28 transceivers. And there are a variety of switches which support QSFP28 interfaces on the market. However, 100G QSFP28 transceiver is still not cheap in the current market. For example, the price of a 100GBASE-SR4 QSFP28 transceiver is generally more than $2000.00. However, in fiber-mart.COM, supported by OEM, the price is much more favorable. A 100GBASE-SR4 QSFP28 transceiver only cost $650.00 in fiber-mart.COM. The following chart is detailed information of 100G QSFP28 transceivers in fiber-mart.COM.

With the development of wavelength-division multiplexing (WDM) technology, the network traffic volume is increasing and the demand for more network bandwidth is also on the rise. By converting the operating wavelength of the incoming bitstream to an ITU-compliant wavelength, WDM transponder serves as a key component in WDM system. As an important technology in the fiber optical network, WDM is moving beyond transport to become the basis of all-optical networking. And how to optimize WDM network has always been a hot topic. The transponder is a device to optimize the performance of WDM network, which plays an important in the whole system of WDM network. This article will introduce you the information on WDM transponders.

What Is WDM Transponder?

Also called as an OEO (optical-electrical-optical) transponder, a WDM optical transponder unit is an optical-electrical-optical wavelength converter, which has been widely adopted in a variety of networks and applications. The picture below shows us how a bidirectional transponder works. In this picture, the transponder is located between a client device and a DWDM system. And we can see clearly that, from left to right, the transponder receives an optical bitstream operating at one particular wavelength (1310 nm), and then converts the operating wavelength of the incoming bitstream to an ITU-compliant wavelength and transmits its output into a DWDM system. On the receive side (right to left), the process is reversed. The transponder receives an ITU-compliant bit stream and converts the signals back to the wavelength used by the client device.

The Application of a WDM Transponder

According to its function, the application of a WDM transponders can be classified into the following types.

Wavelength Conversion. It is known to us that when a CWDM Mux/Demux or DWDM Mux/Demux is added into a WDM network, there is a requirement to convert optical wavelengths like 850nm, 1310nm and 1550nm to CWDM or DWDM wavelengths. Then the OEO transponder comes to assist. The OEO transponder receives, amplifies and re-transmits the signal on a different wavelength without changing the signal content.

Fiber Mode Conversion. Multimode fiber optic cables (MMF) are often used in short distance transmission, while single-mode fiber optic cables (SMF) are applied in long optical transmission. Therefore, in some network deployment, considering the transmission distances, MMF to SMF or SMF to MMF conversions are needed. WDM transponders can convert both multimode fiber to single-mode fiber and dual fiber to single fiber.

Signal Repeating. In long haul fiber optic transmission, WDM transponder also can work as repeaters to extend network distance by converting wavelengths (1310nm to 1550nm) and amplifying optical power. The OEO converters convert the weak optical signals from the fiber into electrical signals, and regenerate or amplify, then recover them into strong optical signals for continuous transmission.

WDM Transponder and FMT Solution

At fiber-mart, OEO transponders are made into small plug-in cards to be used on the FMT platform. FMT platform makes devices like EDFA, OEO, DCM, OLP and VOA into plug-in cards and provides standard rack units as well as free software to achieve better management and monitoring. In addition, FMT series products like OEO, DCM and OLP also have higher performance than that of old ones. FMT series OEO transponder can convert optical signals into DWDM wavelengths, reducing the fault risk caused by high power consumption of DWDM fiber optic transceiver. Since the OEO transponder is made into small plug-in card in the FMT platform, it only occupies one slot in the special designed chassis when installed, thus saving a lot of space. In addition, all these FMT plug-in cards, including OEO, in a rack unit share the same power source and support hot plug & play operation. And they can be inserted or removed flexibly in the racks for DWDM networking.

Conclusion

Since the OEO or WDM transponder plays an important role in WDM network, such as receiving, amplifying and re-transmitting the signal on a different wavelength, adding an OEO transponder into the WDM network is very essential. The OEO transponders in our FMT series are made into small plug-in cards with high quality to ensure good transmission performance. For more information on our FMT system, please visit http://www.fiber-mart.com.

With the improvement of people’s living standard, nowadays a single network access gradually cannot satisfy people’s demand for network now, CWDM system support for the characteristics of business more and more get the attention of people, can also provide E, FE, GE, STM 1/4/16 SDH and ATM signaling, CATV video interface and other businesses such as access CWDM system solutions, to meet the requirements of people now.

Radio and television networks in recent business growth is faster in a given area, is the region development education network access project, due to the previous optical fiber network resources is mainly used in cable television network, optical fiber resources is not so rich, many county to the town had no residual fiber resources, to increase the data business, now want to be in the original on the fiber optic cable TV network transmission using again, plus information data signals, or want to lay out the other cable the main work, need to solve as many towns in this area belongs to mountainous area, cable laying is not very convenient, considering various factors such as resources, cost, on the radio and television networks company specialized in CWDM system to conduct a comprehensive performance analysis and product testing.And start in areas such as education network access to a project on each node USES many fiber-mart.com CWDM system equipment.

The radio and television networks of CWDM project at present is mainly used to implement the education network (10/100 MBPS Ethernet) hybrid transmission signals and the cable television network, the current direction of projects with a total of eight different contact, sharing the 3 sets of fiber-mart.com the CWDM system equipment.

In this scenario, A computer room – B node transfer 2 10/100 MBPS data signals and A cable TV signal, which is based on WDM CWDM access, two 10/100 MBPS signals after fiber-mart.com C5002S through fiber-mart.com HA – WDM multiplexer, and cable television signals and reuse all the way to A single fiber, transfer to the access point B region, middle transmission distance of 50 km, implements and Ethernet cable TV signal on the single fiber CWDM module of hybrid transmission.

A room – C nodes use sea pegatron C5002S system combined with high speed and CWDM terminal transceiver effectively cooperate with access, realize two-way 10/100 MBPS of hybrid transmission over A single optical fiber.

A-D-E by fiber-mart.com C5004S system combining various nodes of high speed and the corresponding CWDM transceiver implementation 4 10/100 MBPS signals on A single optical fiber access project, through the high speed connection between each contact, through the terminal CWDM wavelengths optical transceiver connected to A contact switch, after the C5004S system in the computer room 4 different signals, respectively in different wavelengths transmitted to each destination, after D primary school, through high speed download local signal, the remaining 3 to continue down the road signal to the corresponding destination.

Save fiber resources CWDM (Coarse where division multiplexing) Coarse wavelength division multiplexing system, which USES optical multiplexer in the different optical fiber transmission wavelength multiplexing in a single fiber transmission;On the receiving end of A link, using wavelength multiplexer and then revert to the original wavelength, using optical fiber all the way, on the whole link is solved effectively under the condition of the optical fiber resources extremely nervous network access, this scenario, A, D, E, between transmission on A single fiber and four 10/100 MBPS (also can be 1000 MBPS) signal, A room – B node is in the original cable TV signal transmission on A single fiber loading 2 10/100 MBPS signals, save A lot of fiber resources. 2.More business and high bandwidth CWDM is a according to the practical application to the transfer rate of adaptation based transmission platform, support a variety of business transfer.At each wavelength, the support of the business including 10 m / 100 m / 1000 m Ethernet, 155 m / 622 m / 2.5 G of SDH, 155 m / 622 m ATM business, as well as the Fiber Channel business, and so on.The whole system capacity to play a few Gbps data signal.Fully meet user bandwidth requirements in quite some time.This scenario USES is 10/100 MBPS business with cable TV signal for hybrid transmission.

CWDM system than the price of L band DWDM transceiver is relatively low, due to the power of CWDM is small, small volume, easy to use, thus supporting facilities, personnel training and the late maintenance cost is low.Compared with optical cable project: using CWDM device is opened rapidly, low cost, convenient network upgrades, late and increasing need of signal directly, or replace the higher rate of product, don’t need to change the fiber link, convenient network upgrades, reduces the network upgrade costs.The above scenario A-D-E, if change into 1000 MBPS data signals, the capacity of the network directly to upgrade to the 4 GBPS.

CWDM in hybrid access network in the use of the business.

Recently the building of QSFP-DD (Multi Source Agreement) Group has excited optical communication industry. This group, including 13 members which are all the leading vendors in the industry, like Cisco, Brocade and Finisar, aims to create a upgraded version of QSFP transceiver, which is called QSFP-DD ( double density QSFP) and will be able to support 200G/400G Ethernet.

Introduction

The QSFP-DD is similar to the current QSFP. But there are many differences between the current QSFP. The reason why the new transceiver is called “double density” is related to the current 100G QSFP28 transceivers. The “double density” means the doubling of the number of high-speed electrical interfaces that the module supports compare to regular QSFP28 module.

QSFP-DD and QSFP28

We can understand the QSFP-DD better by comparing it with the current 100G QSFP28 module. QSFP28 transceiver is a four-channel transceiver which is able to transmit and receive 100G per second simultaneously. With the advantages of high speed and low power, QSFP28 transceiver is becoming more popular than other 100G transceivers like CFP2 and CFP4. The 100G QSFP28 transceiver is implemented with four lanes with each supporting data rate of 25G.

The working principle of QSFP-DD is similar with 100G QSFP28 transceiver. The QSFP-DD MSA group will increase the lane to eight. There will be a row of contacts providing for an eight lane electrical interface in QSFP-DD. If modulated by NEZ, each lane of the QSFP-DD can support data rate up to 25G, thus, it can support a total data rate of 200G. If modulated by PAM4, it can support data rate up to 400G with each lane supporting data rate of 50G. The MSA group also announced that the QSFP-DD can enable up to 14.4Tbps aggregate bandwidth in a single switch slot, which can definitely satisfy the increasing need for higher bandwidth.

Another great feature of QSFP-DD is that its system will be backwards compatible, allowing them to support existing QSFP modules and provide flexibility for end users and system designer. This means the data center could save a considerable sum of money in the future upgrading.

Future and Present

The appearance of QSFP28 transceiver has changed the regular development road map of Ethernet. The regular upgrade road is 10G to 40G and then 100G. While the QSFP28 transceiver has changed it from 25G directly to 100G. The road map of this QSFP-DD is also drawing our attention. It is predicted that it will become a useful family of modules for the industry with application at greater than 400G. Meanwhile, there is no efforts underway to define these new speeds but it is expected that QSFP-DD will have a roadmap that supports.

Any way, no matter where the QSFP-DD lead our Ethernet to, it is good news for our future networking system. The creating of this new module will still need some time. For now, many data centers are considering about upgrading their data center with 100G QSFP28 transceivers. And there are a variety of switches which support QSFP28 interfaces on the market. However, 100G QSFP28 transceiver is still not cheap in the current market. For example, the price of a 100GBASE-SR4 QSFP28 transceiver is generally more than $2000.00. However, in fiber-mart.COM, supported by OEM, the price is much more favorable. A 100GBASE-SR4 QSFP28 transceiver only cost $650.00 in fiber-mart.COM. The following chart is detailed information of 100G QSFP28 transceivers in fiber-mart.COM.