Fiber Optics

optical communication

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Fiber Optic Cable Pulling Advices

Fiber optic cable (optical fiber) nowadays is deployed everywhere to feed the insatiable bandwidth needs of mission-critical applications. However, fail to pull fiber optic cable properly will eventually lead to serious network problems and disasters. So, to ensure a smooth and efficient fiber optic cable pulling, installers should get fully prepared, while taking various factors into account to avoid damaging the optical fiber. Here, we offer you this guide for pulling fiber optic cable, and advices to get the work done.

Before Pulling Fiber Optic Cable: Some Precautions

Through the whole fiber optic cable installation process, preparation is the very primary phase – which would have a profound impact on the optical fiber pulling task. To get well-prepared, the following factors must be valued.

1. Avoid Fiber Optic Cable Damage

When pulling fiber optic cable, the first step is to measure and cut the material. The glass fiber within the cable is fragile and requires greater care during the process of optical cable pulling. Generally, broken fiber optic cable is difficult to detect, so extra attention should be paid to avoid damaging fiber optic cable.

2. Despooling Optical Fiber Properly

Improper fiber optic cable pulling and despoiling can cause optical cordage failure. One should also avoid cable twist when despooling fiber optic cable to prevent stressing the fibers. Therefore, optical fiber should be reeled off the spool, not spun over the edge of the spool.

3. Fiber Optical Cable Pulling Force

The pulling force must be kept below a designated limit for the specific fiber cable being installed. This is usually 600 pounds for outside plant (OSP) cable and 300 pounds or less for other cables. When using power equipment to pull OSP cable, tension monitoring equipment or breakaway swivels must always be used.

4. Avoid Bending Optical Fiber Too Tightly

Bending fiber optic cable on too tight a radius is a common problem. A minimum bending radius of 10 cable diameters must be maintained over long-term, static conditions. When fiber optic cable is placed under a tensile load, a minimum of 20 cable diameters is recommended.

Procedures for Pulling Fiber Optic Cable

Step One: Inspect the cable run to ensure there are no sharp bends or corners that exceed the minimum bend radius of the fiber cable.

Step Two: In many runs, if the pulling distance is short enough and the pathway straight enough, fiber optic cable can be pulled by hand. However, first make sure the pull does not exceed the tensile-loading limit established by the manufacturer for installation.

Step Three: With some fiber optic cable, such as outside-plant cable, it may be necessary to attach the pulling grip to strength members that surround the fiber cable core as well as the outer jacket. This is done by sliding the grip past the end of the optical fiber and then cutting the cable jacket back to expose the strength members.

Step Four: Use a swivel when pulling to make sure twists in the pull rope are not translated to the fiber optic cable. Also, use a tension meter to monitor the tension being applied to the fiber cable during the pull.

Step Five: After pulling fiber optic cable, cut off approximately 10 feet of cable from the pulling end to remove any portion of the fiber cable that may have been stretched or damaged during installation.

Note: Leave enough fiber optic cable at either end to reach the work-area and closet terminating locations. You are now ready to terminate or connectorize the fiber cable.

Conclusion

Pulling fiber optic cable is a rather important part in optical fiber installation. During the process, installers should avoid fiber cable damage, despoiling it properly, and take pulling force into account. Since the real optical fiber pulling environment could be more complex, the recommended procedures for fiber optic cable pulling here simply provide guideline, hope it can be helpful.

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Fiber Optic Cable: Single Mode Patch Cable or Multimode Patch Cable?

Fiber optic cable is ubiquitous nowadays to increase network speed and performance. There exist various flavors of fiber optic cable, among which fiber patch cables (fiber jumper cables) are preferable options for using in data centers. There are two variations of fiber patch cables: single mode patch cable and multimode patch cable. So for practical use, is there any difference between single mode patch cable and its multimode counterparts? How about the application scenarios of each. This article explains it from scratch.

Single Mode Patch Cable Overview

Single mode patch cable (single mode fiber jumper) has a core of 8 to 10 microns. In single mode patch cable, light travels toward the center of the core in a single wavelength – this allows the signal to travel over longer distances with relatively less signal loss. Most single mode patch cable is color-coded yellow. Single mode fiber jumper is the best choice for transmitting data over long distances.

Multimode Patch Cable Overview

Unlike single mode patch cable, multimode patch cable has a core of either 50 or 62.5 microns - the larger core gathers more light compared to single mode fiber patch cables. Although more cost-effective than single mode patch cable, multimode cabling only maintain signal quality over short distances. Multimode patch cable is generally color-coded orange (OM1, OM2) or aqua (OM3, OM4). Multimode patch cables are a good choice for transmitting data and voice signals over shorter distances.

Single Mode Patch Cable vs Multimode Patch Cable: How to Choose?

Should I adopt single mode fiber patch cable or multimode version? It totally depends on your network requirements. Single mode patch cable usually used for connections over large areas, such as college campuses and remote offices. Single mode fiber jumper has a higher bandwidth than multimode cable to deliver up to twice the throughput. Multimode patch cables, however, quite contrary to single mode fiber patch cables, are typically used for data and audio/visual applications in local-area networks, and connections within buildings or remote office in close proximity to one another.

Summery

Fiber optic cable with reliable quality is critical for your network performance. Single mode patch cable and multimode patch cable each has unique pros and cons and different using scenarios. Generally, single mode patch cable is best used for distances exceeding 550 meters while multimode cable is more cost-effective for applications up to 550 meters. Nowadays, there is an increasing tendency to choose single mode fiber patch cable, since many service provides will only do single mode cabling for new installs.

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DWDM Topology Design: How to Make it Right?

Network expansion spurs the demand for faster data transmission and higher capacity over the network. In this case, DWDM emerges as a cost-effective solution to handle these issues, working efficiently to combine multiple wavelengths together and sent them over one single fiber. With the ability to carry up to 140 channels theoretically, higher capacity can be achieved by DWDM technology. This article guides you through some basics of DWDM topology.

Common DWDM Topology Overview

DWDM networks are grouped into four major topological configurations: DWDM point-to-point with or without add-drop multiplexing network, fully connected mesh network, star network, and DWDM ring network with OADM nodes and a hub. The requirements of each DWDM topology differ, and based on various application, it may involve different optical components. Besides these four common DWDM topology, there also exists hybrid network topology, consisting of stars and/or rings that are interconnected with point-to-point links.

Configurations of DWDM Topology

This section illustrates the four basic DWDM topology configurations, help to understand the major differences and applications of them.

Point-To-Point Topology

Point-to-point topology is typically found in long-haul transport, which demands for ultra high speed (10-40Gb/s), ultra high aggregate bandwidth, high signal integrity, great reliability, and fast path restoration capability. The transmitter and receiver within this DWDM topology can be several hundred kilometers away, and the number of amplifiers between the two end points is generally less than 10. Together with add-drop multiplexing, point-to-point DWDM topology enables the system to drop and add channels along its path. A DWDM point-to-point system includes lasers, an optical multiplexer and demultiplexer, fibers, optical amplifiers, and an optical add-drop multiplexer.

Ring-Configuration Mesh and Star Networks

Basically, a DWDM ring network includes a fiber in a ring configuration that fully interconnects nodes. Two fiber rings are even presented in some systems for network protection. This ring DWDM topology is commonly adopted in a local or a metropolitan area which can span a few tens of kilometers. Many wavelength channels and nodes may be involved in DWDM ring system. One of the nodes in the ring is a hub station where all wavelengths are sourced, terminated, and managed, connectivity with other networks takes place at this hub station. Each node and the hub have optical add-drop multiplexers (OADM) to drop off and add one or more designated wavelength channels. As the number of OADMs increases, signal loss occurs and optical amplifier is needed here.

In the ring DWDM topology, a hub station works to manage channel assignment so that a fully connected network of nodes with OADM is accomplished. The hub also makes it possible to connect other networks. A DWDM mux/demux can be connected to an OADM node to multiplex several data sources. The following picture demonstrates a simple DWDM ring topology with a hub and two nodes (A and B).

Transmit and Receive Directions of DWDM Hub

In the previous part, we’ve mentioned DWDM hub, which serves as a very essential parts in a DWDM system. Here we further explain the transmit and receive direction of a DWDM hub, proving system solutions for your reference.

Transmit Direction

A DWDM hub accepts various electrical payloads, such as communications transport protoco/Internet Protocol (TCP/IP), asynchronous transfer mode (ATM), STM, and high-speed Ethernet (l Gb/s, 10 Gb/s). Each traffic type (channel) is sent to its corresponding physical interface, where a wavelength is assigned and is modulated at the electrical-to-optical converter. The optically modulated signals from each source are then optically multiplexed and launched into the fiber.

Receive Direction

When a hub receives a WDM signal, it optically demultiplexes it to its component wavelengths (channels) and converts each optically modulated signal to a digital electrical signal. Each digital signal then is routed to its corresponding electrical interface: TCPIIP, ATM, STM, and so on However, that each channel requires its own clock recovery circuitry because all channels may be at different bit rates.

Conclusion

The network topology of your DWDM system depends on various factors, including the number of nodes, maximum traffic capacity, scalability, number of fiber links between nodes and so on. Attentions also should be attached to the network components involved in the DWDM system. Hope this article could help to get more understanding towards DWDM technology.

Source: http://www.fiber-optic-solutions.com/dwdm-topology-design-make-right.html

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IP/WDM vs. IP/OTN: Which One to Choose?

The unceasingly demand for Internet-based services makes carrier IP networks a more critical social infrastructure. Operators are required to offer higher speeds, larger capacities and higher reliability network. There emerge two solutions to tackle this issue: IP/WDM and IP/OTN. IP/WDM consists of core routers connected directly over point-to-point WDM links, whereas IP/OTN connects the core routers through a reconfigurable optical backbone (OTN) consisting of electro-optical cross-connects (OXCs) interconnected in a mesh WDM network. This article guides you to choose between them.

Basics of WDM Technology

WDM technology is nothing new for us since it is rather prevalent especially for long haul data transmission. Its ability to provide potentially unlimited transmission capacity remains to be the most featured benefits. Either by simply upgrading the equipment or by increasing the number of lambdas on the fiber, network capacity can be obtained. It is the best choice for applications where channel density/bandwidth is of high priority. Aside from the bandwidth advantage, it also possesses these compelling merits.

Transparency—Being a physical layer architecture, WDM can transparently support both TDM and data formats such as ATM, Gigabit Ethernet, ESCON, and Fibre Channel with open interfaces over a common physical layer.

Scalability—WDM can leverage the abundance of dark fiber in many metropolitan area and enterprise networks to quickly meet demand for capacity on point-to-point links and on spans of existing SONET/SDH rings.

Dynamic provisioning—Fast, simple, and dynamic provisioning of network connections enable high-bandwidth services in days rather than months.

OTN Network Explanation

ITU-T defines OTN as a set of optical network elements (ONE) connected by optical fiber links, being able to provide functionality of transporting, multiplexing, switching, management, supervision and serviceability of optical channels carrying client signals. OTN was designed to optimize existing resources of a transport network. It is a digital wrapper that provides an efficient and globally accepted way to multiplex different services onto optical light paths. The advantages of OTN consist of the following aspects.

It has the facility to work with DWDM and SDH equipment within banded or mesh networks.

Transmits SDH services, without termination of the signal at each network element, the signal transport is transparent including the clock and byte header.

Easily combine multiple networks and services on a common infrastructure entirely in the optical domain and transparent to the format and the speed of the signal carrying client, allowing you to create a multi-platform client.

The OTN services offering is gully software programmable via a single line card, so that the protocols, connectivity and functionality can be reprogrammed remotely as they change services or customers.

IP/WDM vs. IP/OTN: How to Choose From?

Before we go any further, let’s first look at the basic architecture of each. In the IP/WDM architecture, core routers are connected directly over point-to-point WDM links, whereas in the IP/OTN architecture, they are connected through a reconfigurable optical backbone (OTN) consisting of electro-optical cross-connects (OXCs) interconnected in a mesh WDM network. (See the figure below). We assume that each Point of Presence (PoP) or CO (Central Office) consists of four IP routers. It is clear that in IP/WDM, the routers are connected directly to the WDM systems, which connect them to neighboring PoPs. On the other hand, in IP/OTN, there is an intermediate element (OXC) which is responsible for connecting IP routers from different PoPs.

The major differences of these two approaches include the following aspects:

1. In IP/WDM, traditional transport functions such as switching, grooming, configuration and restoration are eliminated from the SONET/SDH layer and moved to the IP layer which is supposed to be enhanced by MPLS. Alternatively, the optical layer is the one that deals with the aforementioned, exploiting the intelligence of OXCs.

2. IP/OTN solution is more scalable than IP/WDM since the core of the network is based on the more scalable OXCs rather than IP routers.

3. IP/OTN is more flexible to traffic changes than IP/WDM.

4. IP/OTN, the optical transport layer provides the restoration services in a fast and scalable way (optical shared mesh restoration), whereas in IP/WDM restoration is achieved by IP rerouting which is a slow process and may lead to instability in the network.

5. When comparing the cost, IP/WDM appears to be a more cost-prohibitive solution than the IP/OTN architecture. Furthermore, as years go by and total traffic increases, the cost difference between both architectures is more severe.

Conclusion

From what we presented in the article, it is clear that IP/OTN is a more cost-efficient solution. And the savings increase rapidly with the number of nodes and traffic demands between them. Furthermore, IP/OTN is superior over IP/WDM in other qualitative terms like scalability, availability and resiliency. FS.COM endeavors to provide cost-effective and feasible optical network solutions. For more information, please visit www.fs.com.

Source: http://www.fiber-optic-solutions.com/ip-wdm-ip-otn-comparison.html

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CWDM Network: Technology Overview and Common Applications

Fiber exhaust is an inevitable problem constantly faced by carriers since the demand for higher speed bandwidth never ceases. The ever-improving wavelength division multiplexing (WDM) technology nowadays is increasingly used to boost network capacity, enabling carriers to deliver more services over their existing fiber infrastructure. CWDM, as one form of the mature WDM technologies, is a perfect fit for access networks and metro/regional networks. This article addresses the CWDM fundamentals and its common applications, and how CWDM helps to maximize network capacity effectively.

CWDM Technology at a Glance

Coarse wavelength division multiplexing (CWDM) came into prominence as a cost-effective alternative to maximize network capacity in the access, metro and regional network segments. It gains in more popularity in area with a relatively moderate traffic growth due to its simple deployment and low cost. ITU-T G.694.2 defines 18 wavelengths for CWDM transport ranging from 1270 to 1610 nm, spaced at 20 nm apart. But 8 wavelength in the 1470-1610nm band is mostly used since there exist high attenuation in the 1270-1450 nm band. This technology shines out in access network deployments by obtaining the advantages of flexible add-drop capacity and network design simplicity.

Common Applications of CWDM

After going through the basics of CWDM technology, this section will further explain its common applications. CWDM is primarily deployed in two areas: metropolitan and access networks. Let’s see how they could benefit from applying it.

Fiber Exhaust Relief

Fiber exhaust appears to be a severe problem that carriers endeavor to solve, especially for some metropolitan networks where data traffic increases continuously. Adding CWDM to the original optical network presents a cost-efficient and simple approach to this problem. In this case, carriers can add new services over a existing single optical fiber, while not interrupting service for existing customers. This solution is ideally suited for carriers that desires to increase the already installed network capacity without new fiber construction.

Enterprise LAN and SAN Connection

When interconnecting geographically dispersed Local Area Networks (LANs) and Storage Area Networks (SANs), CWDM rings and point-to-point links offer an optimum option. It is beneficial to integrate multiple Gigabit Ethernet, 10 Gigabit Ethernet and Fiber Channel links over a single fiber for CWDM point-to-point applications or for ring applications.

Adoption in Metro Networks With Lower Cost

4 channel CWDM system offers an ideal solution for smaller metro/regional markets which demand for moderate traffic growth. This configuration can expand the available capacity four times over an existing network, enabling less deployment cost than the commonly adopted 8 channel system. Meanwhile, the scalability of this 4 channel system also allows carriers to upgrade to 8 channel systems when the need occurs.

Central Office to Customer Premise Interconnection

Coarse WDM system is also well-fitted for metro-access applications such as Fiber to the Building (FTTB). Let’s take the most widely used 8 channel CWDM network for example, it is capable of delivering 8 independent wavelength services from the Central Office (CO) to multiple business offices located in the same building.

Combining With PON

Passive Optical Network (PON) is a point-to-multipoint optical network to deliver bandwidth to the last mile. It is cost-effective because it uses passive devices (splitters for example) instead of expensive active electronics. The issue exists in PON is that the amount of bandwidth they can support is rather limited. Since CWDM serves to multiple bandwidth, when combining it with PON, each additional lambda becomes a virtual point-to-point connection from a central office to an end user. If one end user in the original PON deployment needs his own fiber, adding CWDM to the PON fiber creates a virtual fiber for that user. Once the traffic is switched to the assigned lambda, the bandwidth taken from the PON is now available for other end users, so the access system can maximize fiber efficiency.

Conclusion

CWDM has clearly become the preferred method for increasing the bandwidth of metro/regional and optical access networks quickly, simply and at lowest cost. And it has proven to be sufficiently robust and reliable for upgrading the optical network to accommodate future growth. Hope this article could help to get a better understanding of coarse WDM technology.

Source: http://www.fiber-optic-solutions.com/cwdm-technology-common-applications.html

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Implementing Passive CWDM to Upgrade Access PONs

Coarse Wavelength Division Multiplexing (CWDM) has proven itself to be a preferred approach to elevate the bandwidth of optical access networks, offering quicker and simpler installation and lower overall cost. Passive CWDM, which requires no electrical power at all, is considered reliable and robust to deploy in the most demanding environment. It generally offers lower cost and more flexible installation and network expansion. This article demonstrates how to use passive CWDM technology to upgrade access PONs.

Why Passive CWDM for Access PONs?

Passive CWDM is an implementation of CWDM that uses no electrical power. It separates the wavelengths using passive optical components. CWDM multiplexing components are compact enough to easily retrofit into existing fiber splice cassettes for installation into street cabinets or other forms of outside enclosure. Besides, it also processes the following merits:

Predictably low equipment and operating cost

Quick and efficient network upgrade

Simplicity of specification and simplicity of deployment

Sufficiently flexible solutions that facilitate expansion

Open standards, nothing proprietary

CWDM and Add/Drop With Access PONs

For PON networks, be it in the ring or point-to-point structures, not all capacity is needed at a single optical node. Therefore, data transported over certain channels may be added/dropped from the fiber as required. And it may be implemented at any CWDM node at any location in the field. The picture below illustrates how to achieve this. This is generally cost effective and simple to perform. A passive CWDM upgrade simply eliminates the need for deployment of additional network equipment.

The advantages of the PON architecture above lies in the low CAPEX, low OPEX and no electrical power required. And that it can be quickly and inexpensively upgraded when additional bandwidth demands arise.

How to Upgrade Access PONs With Passive CWDM?

With the prevalence of FTTH networks, access networks between the central office (CO) and the subscribes must be upgraded to keep pace with the hunger bandwidth. The figure below shows a typical PON architecture, with an optical line terminal (OLT) located in the CO to transmit traffic to approximately 16 to 32 residential drop points, and PON splitters located at fiber distribution hubs between the OLTs and subscribers’ optical network terminals (ONTs), enabling one OLT port and laser transceiver to be shared across many drop points.

Passive CWDM enables better fiber capacity utilization and supports far greater data traffic as the bandwidth demands from the ONTs increase. It permits network operators to implement many more optical nodes over multiple locations with minimal capital investment and virtually no additional operating cost. The following case presents how to use passive CWDM for access PONs upgrade.

Case: In this case, existing subscribers intend to upgrade to higher value-added bandwidth services. The 622 Mb/s downstream capacity between the CO and the OLT, appropriately 20 Mb/s to each subscriber is proven insufficient, which must to increase.

Solution: The adequate bandwidth requires a downstream CO/OLT link bandwidth of 2.5 Gb/s. Multiplying the number of bidirectional channels traveling between the CO and OLT by four demands four CWDM wavelengths. The upgraded passive CWDM based network (shown below) relives the fiber exhaust and boosts the bandwidth of the CO/OLT link. This installation requires four channel-specific (color coded) transceivers plugging into the router/switch, the associated patch cables, the rack-mounted CWDM module and the snap in passive CWDM cassette located in the OLT.

Benefits: The passive CWDM upgrade can be accomplished within hours, while the cost concerning material, labor, equipment and training is far less than that of laying a new fiber cable. Which is both energy-saving and cost-efficient.

Using CWDM to Expand EPON Bandwidth

Passive CWDM is also beneficial to Ethernet PON (EPON). Let’s see how it works in EPON through the case below.

Case: The figure below shows a common EPON architecture, which serves up to 64 subscribers, all sharing a single 1.25Gbps bidirectional optical Ethernet feed line. The theoretical maximum sustainable data-rate for each is roughly 16 Mb/s. The 16Mb/S downstream capacity should be increased since higher bandwidth services become available.

Solution: A four channel passive CWDM extension effectively multiplies the downstream capacity without affecting the upstream traffic. A rack-mounted CWDM unit in the CO and a miniature hardened CWDM module deployed in the fiber distribution hub increases the revenue earning potential while minimizes OPEX and CAPEX.

Benefits: In this case, the four channel CWDM upgrade promotes the throughput of the downlink by a factor of four while demanding minimal modification of the existing infrastructure.

Conclusion

A passive CWDM method provides the unique advantages of low CAPEX, minimal OPEX and rather simple yet reliable upgrade planning and implementation. More importantly, passive CWDM also preserves scalability and network flexibility for future network expansion and bandwidth demand changes. Hope this article is informative enough for getting a better understanding towards passive CWDM.

Source: http://www.fiber-optic-solutions.com/passive-cwdm-upgrade-access-pons.html

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Hybrid CWDM-DWDM System Boosts Your Network Capacity

Should I choose a medium capacity but more cost-effective CWDM solution, or to adopt the cost-prohibitive DWDM approach with comparably enhanced capacity? This is a problem that consistently faced by WDM technology users. The wrong decision, however, may inevitably lead to bandwidth shortage or even potential bankruptcy derived from unnecessary capacity investment. This article introduces the hybrid CWDM-DWDM solution that combines both CWDM and DWDM technologies within a single system, helping decrease costs and simplify installation while maintain the flexibility to upgrade.

Hybrid CWDM-DWDM System Explanation

Hybrid CWDM-DWDM system utilizes the technology to merge DWDM and CWDM traffic seamlessly at the optical layer. Which allows carriers to add many channels to networks originally designed for the more limited CWDM capacity and reach. In other words, hybrid CWDM-DWDM system is used to empower CWDM system by integrating CWDM and DWDM equipment. Hybrid CWDM-DWDM system deliver true pay-as-you-grow capacity growth and investment protection. It offers a simple, plug-and-play option for creating hybrid system of DWDM channels interleaved with existing CWDM channel plans.

Benefits of Hybrid CWDM-DWDM System

Hybrid CWDM-DWDM system typically provides three benefits for carriers and users:

Reduced Cost: CWDM is more cost-effective than DWDM due to the lower cost of lasers and the filters used in CWDM modules. This cost saving becomes quite significant for large deployments.

Pay-As-You-Grow: Adding one new channels at a time allows for on-demand service introduction with minimal initial investment—a critical feature in terms of reduced OPEX and CAPEX spending.

Investment Protection: Carriers and end-users need always to bear the future growth in mind. With hybrid CWDM-DWDM system, carriers no longer have to choose between CWDM and DWDM—both options can be deployed simultaneously or as part of future growth. This module can be used in either CWDM or DWDM system. Current capital investment can always be used in the upgraded network.

How to Deploy Hybrid CWDM-DWDM System

The CWDM wavelength grid typically has 16 channels spacing at 20 nm intervals, with 8 channels (1470 nm-1610 nm) of them are most commonly used. Within the pass band of these channels, it is capable of adding 25 100 GHz spaced DWDM channels under the 1530nm envelope and 25 more under the 1550nm envelope. However, it is not so practical to add 25 DWDM channels in the pass-band of both the 1530nm and 1550nm CWDM channels. DWDM filter technology does allow 38 additional channels to clear the CWDM archway, which is shown as following.

To add more DWDM channels to the MUX side of the conventional CWDM system, one need to plug in a DWDM MUX with the appropriate channels under the pass band of the existing CWDM filters. The picture below illustrates the configuration of a CWDM system upgraded with 38 additional 100 GHz spaced DWDM channels. This hybrid CWDM-DWDM system consists of 38 DWDM channels and the existing 6 CWDM channels. The equipment required to go from the first architecture to the second are 2 DWDM MUX/DEMUXs, as well as the additional transmitter and receiver pairs. The additional loss incurred by the upgrade is equal to the additional loss of the DWDM elements and the additional connection points.

Flexible Hybrid CWDM-DWDM System Solution by FS.COM

The most vital elements concerning hybrid CWDM-DWDM system are the CWDM MUX/DEMUX and DWDM MUX/DEMUX. FS.COM developed and introduces FMU series products to facilitate installation and operation of WDM MUX/DEMUX. The prominent feature of this series products is that they combine the MUX/DEMUX into half-U plug-in modules, which can be installed in a 1U rack. As for hybrid CWDM-DWDM system, a FMU CWDM MUX/DEMUX and a DWDM half-U plug-in module can be installed together in a FMU 1U rack chassis, facilitating connections of these two modules while allowing for better cable management and network operation in hybrid CWDM-DWDM system.

Conclusion

Hybrid CWDM-DWDM system generally offers a cost-effective and future-proofing approach for service providers and end-users, by overcoming the obstacles faced by users of WDM technology today, providing a starting platform that scales smoothly and protecting the investment. A user can commence with the more cost-effective CWDM technology and then later add DWDM in the when the capacity is required. FS.COM FMU series WDM solution makes the process even easier and more flexible. For more information, please visit www.fs.com or contact [email protected].

Source: http://www.fiber-optic-solutions.com/hybrid-cwdm-dwdm-boost-network-capacity.html

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Extending DWDM Network Reach With Raman Amplifier

Raman amplifier is appearing to be a critical technology which is consistently developed for using in optical communication networks. Typically applied in long-haul networks, Raman amplifier is also expected to extend its reach in dense wavelength-division multiplexing (DWDM) networks. This escalating adoption, therefore, is fueled by the massive bandwidth demand that network operators are continuously facing. This article explains the necessities and related considerations for deploying Raman amplifier in DWDM networks.

Why Use Raman Amplifier and How it Works?

Raman amplifier has proved itself beneficial for applications in 100G network and above. It is gaining in popularity because it is capable of meeting the need for higher transmission capacity. There exist various alternatives to enhance network transmission capacity: like extending beyond the C-band into the L-band, increasing the symbol rate or increasing spectral efficiency. Any of the options requires a higher optical signal-to-noise ratio (OSNR). Raman amplifier generally offers higher OSDR required to increase capacity, while eliminates the need for expensive opto-electronic regeneration.

Raman amplification generally leverages the network fiber as the gain medium. By adding a distribution Raman amplifier to a fiber span with EDFAs, signal power loss can be decreased. The commonly deployed counter-propagating Raman amplifier consists of one or more Raman pump lasers and a wavelength combiner, so that the Raman pump wavelengths are transmitted into the fiber in the opposite direction of the signal. Signal propagating along the fiber will be attenuated, but as it moves along toward the fiber end where the Raman pump is located, it will start to experience some gain from the Raman pump wavelength. The higher power in the signal thus increases OSDR, which enables longer fiber span, higher capacity and spectral efficiency, and longer link distance.

Solutions for Extending DWDM Reach With Raman Amplifier

With EDFA being the default amplifier for use in DWDM transmission, Raman amplifier is found critical and effective in complementing the EDFA for transmission distance expansion. It typically provides an improvement in performance that cannot be obtained by EDFA alone. The application of Raman amplifier in DWDM network is demonstrated below.

The following picture illustrates the effect of Raman amplification on a simple multispan link with 23 dB loss per span compensated by 23 dB of amplification. In one case, each span loss is compensated with an EDFA, while in the other case, the gain is divided between the distributed Raman amplifier and the EDFA. Inferring from the figure, it is clearly that with the hybrid EDFA/Raman amplification, the OSNR curve has shifted upwards towards higher OSNR values. This means the link can obtain higher OSNR for the same span number, or, the same OSNR for a much larger span number. By incorporating Raman amplifier into DWDM networks, the link becomes more robust, with more margin available for future repairs or changes along the link.

Deployment Considerations for Raman Amplifier

It is undoubted that Raman amplifier can provide significant benefit to DWDM networks, what should be noticed here is that, there are also several key precautions to deploy Raman amplifier in real-life environment, which must be addressed so that the potential benefits can be fully realized.

Keep Fiber Clean

When deploying Raman amplifier in a DWDM system, the equipment needs to be connected to the network fiber with minimum connection loss. Since contamination like dust and dirt, or misalignment is detrimental to fiber attenuation, network operators must keep the fiber and connectors clean during the connection process, not degrade the performance of the system.

Connection Loss

Connection loss could have a significant impact on the whole network. The following picture shows the reduction in Raman gain due to different connector losses when the connector is located very close to the Raman pump. The three curves correspond to different fiber attenuation levels at 1550 nm. In this example, a Raman amplifier with a net gain of 15 dB is involved, a 1 dB connection loss can result in a 4 dB gain reduction, and a 2dB connection loss increases the reduction in Raman gain to 7 dB.

Location of the Loss Element

The location of the loss element serves as a vital factor. The figure below shows the Raman gain reduction according to different position of the loss elements, at 0 km, 5 km, 10 km and 20 km away from the Raman pump. It reveals that the Raman gain reduction is lower if the connection loss is located further away from the Raman pump. This is because most of the Raman gain occurs close to the Raman pump. We can also conclude that most of the gain obtained through Raman amplification is obtained in the region of the effective length of the fiber, which is in the ~20km range.

Conclusion

Adoption of Raman amplifier significantly consolidates optical link while extends transmission reach in DWDM networks. Raman amplifier also serves as a good implementation of EDFAs, enabling applications which are not feasible or practical with conventional EDFA technology. Thus increasing the distance and capacity of long-haul DWDM systems.

Source: http://www.fiber-optic-solutions.com/extend-dwdm-reach-raman-amplifier.html

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Optical Transponder (O-E-O) Used in WDM Network

WDM technology is commonly used in today’s optical network. It basically assigns each service (10G LAN, SONET/SDH, Fiber Channel, etc) an independent dedicated wavelength—which then is multiplexed into one single fiber. Eliminating the use of multiple fibers while increasing fiber capacity, WDM system is beneficial to both service providers and end users. Optical transponder, also referred to as O-E-O (optical-electrical-optical), serves as an integrated part of WDM system and it is critical for signal transmission in the whole system. This article will guide you through how optical transponder operates in a WDM network.

Basics of Optical Transponder (O-E-O)

The optical transponder (O-E-O) works as a re-generator which converts an optical input signal into electrical form, then generates a logical copy of an input signal and uses this signal to drive a transmitter to generate an optical signal at the new wavelength (optical-electrical-optical). Its most prominent feature is that it automatically receives, amplifies, and then re-transmits a signal on a different wavelength without altering the data/signal content. Clients can be electrical or optical (1310 or 1550 nm), co-located or some distance away. Line side interfaces can be fiber, CWDM or DWDM with a variety of reaches supported.

Common Applications of Optical Transponder (O-E-O)

Optical transponder is widely accepted in WDM networking and many other applications. let’s go through some commonly used ones.

1. Multimode to single-mode conversion

Some optical transponders can convert from multimode to single-mode fiber, short reach to long reach lasers, and/or 850/1310 nm to 1550 nm wavelengths. Each optical transponder module is protocol transparent and operates fully independent of the adjacent channels.

2. Redundant fiber path

Each optical transponder module can also include a redundant fiber path option for extra protection. The redundant fiber option transmits the source signal over two different optical paths to two redundant receivers at the other end. If the primary path is lost, the backup receiver is switched on. Since this is done electronically, it is much faster and more reliable.

3. Repeater

As an optical repeater, some optical transponders effectively extend an optical signal to cover the desired distance. With the clock recovery option, a degraded signal can be dejittered and retransmitted to optimize signal quality.

4. Mode Conversion

Mode conversion is one of the quickest and simplest ways of extending multimode optical signals over greater distances on signal-mode fiber optics. And most receivers are capable of receiving both multimode and single-mode optical signals.

5. Wavelength Conversion

Wavelength conversion in commercial networks today is only carried out by optical transponder. We know that optical network equipment with conventional fiber interfaces like LC, SC, ST, etc operates over legacy wavelength of 850 nm, 1310 nm, and 1550 nm. Which means they must be converted to CWDM or DWDM wavelength to fit in the system, and this is what WDM transponders used for—converse wavelength by automatically receiving, amplifying, and re-transmitting a signal on a different wavelength without altering the data/signal content. The following picture depicts the conversion process: a 10G switch (with signal output of 1310 nm) is to be linked to a CWDM Mux/Demux channel port (1610 nm). An optical transponder with a standard SMF SFP+ and a 1610nm CWDM SFP+ is adopted between the switch and CWDM Mux/Demux, thus the wavelength conversion is realized by the optical transponder.

Network Structure with Optical Transponder

Then how exactly optical transponder benefits your network system? Here we provide two possible configurations of network over WDM ring which deploys optical transponder.

For line network over a WDM ring

The line network consists basically of two point-to-point links between A-B and B-C, each requiring transponders at the endpoints. If node B fails, communication between A and C should still be possible, because B can be bypassed by the two adjacent optical transponders. For this the protection in/outputs of the transponders are connected by a bypass link. If node B fails, S1 in both transponders switch to the protection connection.

For star network over a WDM ring

As for a star network over a WDM ring, where the nodes A, C and D are connected to the star node B. Node B has a backup node B’ for redundancy. Here the protection in/outputs of the transponders are used to connect the nodes A, C and D to node B’ if node B failed.

Conclusion

Optical transponder holds a critical position in WDM networking system and cannot simply be underestimate. We have illustrated the functionality and applications of optical transponder, as well as presenting possible configurations of network over WDM rings. Hope that may help you to have a better understanding of the optical transponder.

Source: http://www.fiber-optic-solutions.com/optical-transponder-o-e-o-wdm-network.html

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How to Overcome the Challenges of Adopting WDM-PON in FTTx?

The bandwidth demand in the access network has been increasing rapidly over the past several years. Passive optical networks (PONs), as the most economical FTTx architecture that needs no power supply, have evolved to provide much higher bandwidth in the access network. A PON is a point-to-multipoint optical network, where an optical line terminal (OLT) at the central office (CO) is connected to many optical network units (ONUs) at remote nodes through one or multiple 1:N optical splitters. WDM-PON combines the virtues of point-to-point dedicated connections with the fiber efficiency and economics of PON, which is considered as a candidate solution for FTTx network. This article offers solutions for deploying WDM-PON in regard to its cost and technical challenges.

WDM-PON Technology Explanation

WDM-PON is the passive optical network (PON) based on wavelength division multiplexing (WDM) technology, which delivers higher network security. This system allows ONUs to have light sources at different tuned wavelengths coexisting in the same fiber, increasing the total network bandwidth and the number of users served in the optical access network. The CO contains multiple transceivers at different wavelengths with each output wavelength creating a dedicated path or channel for a particular user by passing through a wavelength selective/dependent element at the remote node (RN). Wavelength selection can also be achieved by filtering at the user. The upstream connection similarly utilizes a dedicated wavelength channel.

Why Apply WDM-PON in FTTx Networks?

We have known that WDM-PON supplies each subscriber with a wavelength instead of sharing wavelength among 32 or even more subscribers in TDM PON, thus providing higher bandwidth provisioning. WDM-PON is regarded as a candidate solution for next-generation PON systems in competition with TDM PON for possessing the following advantages:

WDM-PON allows each user being dedicated with one or more wavelengths, thus allowing each subscriber to access the full bandwidth accommodated by the wavelengths.

WDM-PON networks typically provide better security and scalability because each home only receives its own wavelength.

The MAC layer control in WDM-PON is more simplified as compared to TDM PON because WDM-PON provides P2P connections between the OLT and the ONU, and does not require the point-to-multipoint (P2MP) media access controllers found in other PON networks.

Wavelength in a WDM-PON network is effectively a P2P link, thus allowing each link to run at a different speed and with a different protocol for maximum flexibility and pay-as-you-grow upgrades.

WDM-PON Challenges: How to Deal with Them?

Despite these attractive features, there are also some demerits that hinder the implementation of WDM-PON networks.

When implementing WDM-PON, one should apply wavelength routers or power splitters in the ONUs, and both of the methods need a colorless ONU.

As for long reach WDM-PON system, the protection is necessary to ensure the network reliability and performance.

Concerning the challenges that remain in WDM-PON deployment, here we provide some solutions for your reference.

For Colorless ONU

The ONUs in WDM-PON need to be colorless, which means no ONU is wavelength specific in order to reduce the costs of operation, administration, maintenance and production. Local emission is proposed to solve this problem. There basically exist two local emission approaches: wavelength tuning and spectrum slicing. The ONU of the wavelength tuning approach consists of a tunable laser diode (TLD) as a transmitter (Tx), an optical receiver (Rx) with wavelength selector (WS), and a WDM coupler that divides or combines the upstream and downstream signals. The configuration of the ONU in the spectrum slicing approach is similar to that of wavelength tuning approach, except that a broadband light source (BLS) with WS is used instead of the TLD.

For Long-Reach Protection

As for long-reach network, protecting the feeder fiber that transmits data from potential damage is vital. Then how to achieve the protection? It is suggested to adopt 3-dB optical couplers, which can be used to split or combine the path of WDM signals to or from both the working and protection fibers in the OLT or in the wavelength router. Note that the OLT and the wavelength router are typically located in the central office (CO) and in the access node (AN) respectively. However, this protection method has a low loss budget because of the adoption of the 3-dB optical couplers. To this end, a wavelength-shifted protection scheme has been proposed, which is deploying the cyclic property of the 2×N athermal arrayed-waveguide grating (AWG) and two wavelength allocations for working and protection. In this case, 3-dB optical couplers are not needed.

Conclusion

WDM-PON is proving to be the most promising long-term, scalable solution for delivering high bandwidth to the end user. Meanwhile, advances in key device technologies had laid the foundation for realization of a high performance, low cost WDM based PON system. Thus, in competition with other high-speed access network technologies, WDM-PON is considered the most favorable for the required bandwidth in the near future.

Source: http://www.fiber-optic-solutions.com/overcome-challenges-wdm-pon-fttx.html

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How Does Erbium Doped Fiber Amplifier (EDFA) Benefit WDM Systems

Optical network that involves WDM (wavelength division multiplexing) currently gains in much popularity in existing telecom infrastructure. Which is expected to play a significant role in next generation networks to support various services with very different requirement. WDM technology, together with EDFA (Erbium Doped Fiber Amplifier), allowing the transmission of multiple channels over the same fiber, that makes it possible to transmit many terabits of data over distances from a few hundred kilometers to transoceanic distances, which satisfy the data capacity required for current and future communication networks. This article explains how can WDM system benefit from this technology.

Basics of EDFA

The key feature of EDFA technology is the Erbium Doped Fiber (EDF), which is a conventional silica fiber doped with erbium. Basically, EDFA consists of a length of EDF, a pump laser, and a WDM combiner. The WDM combiner is for combining the signal and pump wavelength, so that they can propagate simultaneously through the EDF. EDFA can be designed that pump energy propagates in the same direction as the signal (forward pumping), the opposite direction to the signal (backward pumping), or both direction together. The pump energy may either by 980nm pump energy or 1480nm pump energy, or a combination of both. The most common configuration is the forward pumping configuration using 980nm pump energy. Because this configuration takes advantage of the 980nm semiconductor pump laser diodes, which feature effective cost, reliability and low power consumption. Thus providing the best overall design in regard to performance and cost trade-offs.

Why EDFA Is Essential to WDM Systems?

We know that when transmitting over long distance, the signal is highly attenuated. Therefore it is essential to implement an optical signal amplification to restore the optical power budget. This is what EDFA commonly used for: it is designed to directly amplify any input optical signal, which hence eliminates the need to firstly transform it to an electronic signal. It simply can amplify all WDM channels together. Nowadays, EDFA rises as a preferable option for signal amplification method for WDM systems, owing to its low-noise and insensitive to signal polarization. Besides, EDFA deployment is relatively easier to realize compared with other signal amplification methods.

4-Channel WDM System With or Without EDFA: What Is the Difference?

Two basic configurations of WDM systems come in two forms: WDM system with or without EDFA. Let’s first see the configuration of WDM system without using it. At the transmitter end, channels are combined in an optical combiner. And these combined multiple channels are transmitted over a single fiber. Then splitters are used to split the signal into two parts, one passes through the optical spectrum analyzer for signal’s analysis. And other passes through the photo detector to convert the optical signal into electrical. Then filter and electrical scope is used to observe the characteristics of signal. In this configuration signals at long distance get attenuated. While this problem can be overcome by using erbium doped fiber amplifier.

As for WDM system which uses EDFA, things are a little bit different. Although the configuration is almost the same as WDM system without it, some additional components are used. These components are EDFAs which are used as a booster and pre-amplifier, and another additional component is optical filter. With the adoption of optical amplifier, this system doesn’t suffer from losses and attenuation. Hence, it is possible to build broadband WDM EDFA which offer flat gain over a large dynamic gain range, low noise, high saturation output power and stable operation with excellent transient suppression. The combination provides reliable performance and relatively low cost, which makes EDFAs preferable in most applications of modern optical networks.

Conclusion

Among the various technologies available for optical amplifiers, EDFA technology proves to be the most advanced one that holds the dominate position in the market. In future, the WDM system integrated with high performance EDFA, as well as the demand for more bandwidth at lower costs have made optical networking an attractive solution for advanced networks.

Source: http://www.fiber-optic-solutions.com/fiber-amplifier-edfa-wdm-systems.html

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CWDM and DWDM for Metro Networks: How to Make it Economical?

Fiber exhaust still appears to be a common problem faced by most metro (or metropolitan) networks. Although the cost of fiber optic cable is consistently dropping, the trenching, labor, and other installation costs towards optical fiber stay rather high. This may partially explain why an increasing number of metro networks incline to adopt WDM technology to enhance fiber capacity. It is known that WDM technology used in metro networks generally takes two forms: coarse WDM (CWDM) and dense WDM (DWDM). This article will deliver an overall comparison of CWDM and DWDM in metro networks, from the perspective of the roles each plays and the operating cost. Help you to decide how to reach an economical solution.

CWDM vs. DWDM: Different Role in Metro Network

As for the major difference between the two WDM technology, their names imply it all: is the channel spacing within the window of the optical spectrum (see the picture below). CWDM has a wider pass-band that spaced at 20 nm apart, which allows for the use of less expensive components like uncooled lasers and thin-film filter technology. The cost advantage of CWDM makes it a more appropriate alternative for the shorter distance typically found in metro access networks.

However, metro networks sometimes demand for longer distance and more wavelengths that CWDM simply cannot satisfy, then DWDM with its narrow channel spacing (0.8 nm) should be put into use. The problem is that the components related to the latter are too expensive for some edge networks. In this case, the best solution is to combine both CWDM and DWDM in metro area networks.

CWDM in the Metro Access

CWDM nowadays commonly supports at least eight of the eighteen ITU-T G.694.2 defined channels over distances of up to 80 km. With simple point-to-point and ring network topology, CWDM eliminates the need for erbium doped-fiber amplifier (EDFA) typically associated with DWDM. CWDM's lower cost and small footprint fit well with customer premises and co-location installations. And due to the readily available of Gigabit interface converters and small form factor pluggable (SFP) transceivers for CWDM platform, it gains in much popularity in enterprise and storage networks. CWDM is most fit in networks with the following features:

Low channel count of 4 to 8 channels

Transmission rates of <2.5 Gbits/sec per channel, and short distances of <80 km

DWDM in the Metro Core

Carriers are consistently looking for a cheaper and simpler version of long-haul DWDM, which drives the equipment suppliers to adapt DWDM systems accordingly. Banded wavelength filters, elimination of dispersion compensation, and more tolerant channel spacing were seen as ways to accomplish this goal. Nowadays, DWDM is well suited to high-capacity core networks in the metro, and to regional extensions between metro areas.

Cost Concerning CWDM and DWDM

The cost is still presented as a key difference in metro network systems. DWDM lasers are generally more expensive than those applied in CWDM system, the cooled DFB lasers offer cost-effective solutions for high-capacity large metro rings. And the cost of the this system is amortized over the large number of customers served by the systems. Whereas for metro access networks that demand for lower-cost and lower-capacity systems, it heavily depends on what the customer is willing to pay for broadband service. Since a metro access application would have fewer wavelengths, so based on equipment cost, CWDM is a more profitable solution for metro access points where cost is more important than capacity.

The Future of CWDM and DWDM in Metro Network

Some vendors offering both CWDM and DWDM technologies have merged the system building blocks onto a single platform. This approach allows the de-multiplexed CWDM traffic to be directly connected to DWDM transponders, saving equipment and space. It also enables end-to-end performance monitoring and cost optimization throughout the entire metro network. Then there is no need to choose between these two WDM technologies. The better choice is an integrated solution that makes use of the economies of CWDM for shorter distances, and provides the power of a DWDM network where longer distances and more capacity are needed. The result is an integrated, economical network that doesn't require a carrier to compromise on quality, quantity, or cost. The DWDM building blocks are shown below.

Conclusion

From what we have discussed in this article, we can conclude that metro networks will benefit from the mixture of CWDM and DWDM systems. And metro networks are becoming more flexible over this converged solution: with CWDM fitting the needs of today, and DWDM for the growing demand for increased coverage in the future. Take advantage of both the coarse and dense WDM technology, this integrated metro network that delivers much reliability and flexibility is the trend of the future.

Source: http://www.fiber-optic-solutions.com/cwdm-dwdm-metro-networks-economical.html

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Comparison Between CFP-100G-SR10 and CFP-100G-LR4 Module

Although 10/40G Ethernet nowadays still captures the major position in the world of telecommunication, service providers and enterprise data centers are actually undertaking a transformation of infrastructures. Which fuels the demand for higher speeds, greater scalability, and better performance and reliability, making migration to 100G network an inevitable trend. Optical transceiver modules always pertain to an integral part of overall system design, as for 100G CFP modules, the options vary widely. This article makes a comparison of the most commonly two: CFP-100G-SR10 and CFP-100G-LR4 transceiver module.

Basics of 100G CFP Transceiver Module

CFP transceiver module is a hot pluggable form factor designed for optical networking applications. CFP the acronym from 100G (here C equals 100 in Roman numerals) form factor pluggable. The name clearly indicates that CFP transceiver module is introduced typically for 100G interfaces. To make it easier to understand, let’s begin with general CFP architecture. It basically consists of two parts—electrical interface interacting with equipment, and line card interface and optical line interface.

From equipment line card to electrical interface, CFP has several “M-Lines” with 10Gbps speed. If CFP is working 100GBase-LR4 mode, then it has 10 x 10Gbps M-Lines. As for 40GBase-LR4, it uses 4 x 10Gbps M-Lines. The so called “gear box”is electrical 10:4 mux/demux module aggregating up to 10 M-Line interfaces in maximum 4 N-Line interfaces. Each N-Line is 25Gbps for 100GBase-LR4 and 10Gbps for 40GBase-LR4. The N-Line is converted to optical signal with different wavelength and all four wavelengths are transmitted to CFP line interface using built in passive optical multiplexers.

CFP-100G-SR10 and CFP-100G-LR4 Overview

100G CFP modules offer connectivity options for a wide range of service provider transport, data center networking, and enterprise core aggregation applications. The basic information of CFP-100G-SR10 and CFP-100G-LR4 module is provided below.

CFP-100G-SR10 Module

CFP-100G-SR10 is an IEEE standardized CFP module supporting link lengths of 100 m and 150 m respectively on laser-optimized OM3 and OM4 multifiber cables. It primarily enables high-bandwidth 100-gigabit links over 24-fiber ribbon cables terminated with MPO/MTP-24 connectors. It can also be used in 10 x 10 Gigabit Ethernet mode along with ribbon to duplex fiber breakout cables for connectivity to ten 10GBASE-SR optical interfaces. CFP-100G-SR10 interface serves as a more cost-effective solution, which is optimized for data center application and is limited to short distances.

CFP-100G-LR4 Module

CFP-100G-LR4 is standardized by IEEE using standard LC dual fiber interface with single-mode cable, but running four optical wavelengths each direction (1295.56 nm, 1300.05 nm,1304.59 nm, 1309.14 nm) and muxing/demuxing of these wavelengths happening inside CFP module. Each wavelength is running at 25.78 Gbps and it is possible to achieve up to 10 km. Compared to CFP-100G-SR10, CFP-100G-LR4 delivers much better reach for long-haul applications, but at a cost premium.

Comparison Between CFP-100G-SR10 and CFP-100G-LR4

In this section, we’re trying to figure out the difference between CFP-100G-SR10 and CFP-100G-LR4 from the perspective of connectors and cabling used on each. For connectors, 24-fiber MPO/MTP connector is for CFP-100G-SR10 module while dual SC/PC connector for CFP-100G-LR4. Note that only patch cords with PC or UPC connectors are supported. The cabling specification and features for CFP-100G-SR10 and CFP-100G-LR4 are presented in the following diagrams.

Conclusion

Service providers and data centers are embracing the trend of 100G network migrations, IT managers and network designers must think twice when choosing from those various 100G transceiver options. CFP-100G-SR10 is preferred due to lower cost over LR4, but its reaching distance is limited. Whereas CFP-100G-LR4 enables data transmission up to 10 km with higher price. This article generally offers some basic knowledge of CFP-100G-SR10 and CFP-100G-LR4 transceiver modules, the decision actually depends on your specific demands and requirements of your applications. Always be aware of what you need, which will work best for you.

Source: http://www.fiber-optic-solutions.com/cfp-100g-sr10-cfp-100g-lr4-comparison.html

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QSFP28 Transceiver: Making the Switch to 100G Network

As data centers around the world explore their options for increasing network speeds and bandwidth, 10G has been a traditional favorite, and 40G is not able to keep pace with the requirements. In this case, 100G network appears to be a preferable option to accelerate data flow for those bandwidth-hungry applications. QSFP28 transceiver module hence becomes the universal data center form factor for 100G optical transmission. This article will address the necessity of 100G network, while illustrating QSFP28 transceiver modules used in 100G transmission.

100G: The Optical Revolution in Data Centers

The 100G adoption rate in optical landscape is consistently on the rise for the past few years. It is predicted that over half of the data center optical transceiver transmission will make the shift to 100G. The traditional 10G or even 40G may not be enough considering the explosion of data, therefore, 100G is going to become the new standard, and it has the following advantages.

Cost Efficiency—100G now delivers a compelling price point, offering far greater capacity increases for the cost. And it still future-proofing the network with unsurpassed bandwidth.

Proactive Scale—100G offers the expansion and scalability to support the reliability, manageability and flexibility demanded of modern networks while preparing data centers for future bandwidth and speed requirements.

Speed and Capacity—10GG optical transport will not be enough for data intensive industries. Thus 100G is specifically designed to transport enormous amounts of data with ultra-low latency.

Flexibility—100G will be the preferred technology across long-haul networks. 100G networking can be customized, optimized, and easily expanded to allow for changes in the future.

Cost Decrease—The market transition to 100GE is now in full force. The growth in 100G deployments will undoubtedly drive down the cost of 100G transceiver modules.

100G QSFP28 Transceiver Unravel

QSFP28 transceiver generally has the exact same footprint and faceplate density as 40G QSFP+ . Just as the 40G QSFP+ is implemented using four 10Gbps lanes, the 100G QSFP28 transceiver is implemented with four 25-Gbps lanes. With an upgrade electrical interface, QSFP28 transceiver is capable of supporting signal up to 28Gbps signals. Though QSFP28 transceiver keeps all of the physical dimensions of its predecessors, it surpasses them with the strong ability to increase density, decrease power consumption, and decrease price per bit. The Following are some QSFP28 transceivers for different applications.

QSFP28 100GBASE-SR4

100G QSFP28-SR4 came out firstly to support short distance transmission via multimode fiber. This transceiver module can support 100G transmission up to 70m on OM3 MMF and 100m on OM4 MMF. With MTP interface, the 100G QSFP28-SR4 module enables 4×25G dual way transmission over 8 fibers.

QSFP28 100GBASE-LR4

100G QSFP28-LR4 is specifically designed for long distance transmission. The module utilizes WDM technology for 4×25G data transmission, and these four 25G optical signals are transmitted over four different wavelengths. With a duplex LC interface, the 100G QSFP28-LR4 module enables 100G dual-way transmission up to 10 km over single-mode fiber.

QSFP28 100GBAS-PSM4

PSM4 uses four parallel fibers (lanes) operating in each direction, with each lane carrying a 25G optical transmission. It sends the signal down to eight-fiber cable with an MTP interface. The operating distance of 100G QSFP28-PSM4 is limited to 500 m.

QSFP28 100GBASE-DWDM4

DWDM4 uses WDM technology—an optical multiplexer and de-multiplexer to reduce the number of fibers to 2. It can operate on single-mode fiber up to 2 km over duplex LC interface. Compared with QSFP28-LR4, it has shorter transmission distance and lower cost.

100G QSFP28 Cables

In addition to the QSFP28 transceiver modules mentioned above, cables can also be deployed in 100G transmission. The cables can be either direct-attach copper cables (DACs), or active optical cables (AOCs). QSFP28 DACs offer the lowest cost but are limited in reach to about 3 m. They are typically used within the racks of the data center, or as chassis-to-chassis interconnect in large switch and routers. QSFP28 AOCs are much lighter and offer longer reach up to 100 m and more.

Frequently Asked Questions About QSFP28 Transceiver

What Is the Difference Between QSFP28 Transceiver and QSFP+?

These two have the same size form factor and the number of ports, however the lane speeds of QSFP28 transceiver are increased from 10 Gbps to 25 Gbps. The increase in density is even more dramatic when compared to other 100Gbps form factors: 450% versus the CFP2.

How Many QSFP28 Transceiver Moduels Can Fit into One Switch?

With QSFP28 transceiver, a one rack-unit (RU) switch can accommodate up to 36 QSFP28 ports. While many more varieties of transceivers and cables (DACs and AOCs) can plug into these ports.

Conclusion

100G QSFP28 transceiver offers direct compatibility with your existing switches and routers, and it facilitates the process of scaling to 100G networks with the simplicity as 10G networks. With higher port density, lower power consumption and lower cost, QSFP28 transceiver is an ideal alternative for large scale data centers, as well as future network expansions. All the QSFP28 transceiver modules presented in this article are available at FS.COM. For more details, please visit www.fs.com.

Source: http://www.fiber-optic-solutions.com/qsfp28-transceiver-making-switch-100g-network.html

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Fiber Patch Cable Cleaning Recommendations

Fiber optics have expanded the capabilities and possibilities of networks beyond our expectation. Fiber patch cable serves as a common yet indispensable part which determines connection quality between fiber optic equipment, therefore it has no tolerance to any contaminant like dust and dirt. So keeping the end face of patch cables clean to ensure performance and reliability of the network is vital. This article offers general tips on patch cable cleaning, while introduces some professional tools that help simplify the process.

Why Is Patch Cable Cleaning Critical?

It is claimed that over 85% of fiber related problems in data centers, campus, and other enterprise or telecom environments are caused by contaminated connectors or end-faces. Which can often lead to degraded performance, or even worse, failure of the whole network system. So, cleaning consideration is always put in a paramount place in optical network transmission.

To ensure proper performance and reliability, care must be taken with the installation and maintenance of patch cable end face, as well as the removable fiber connectors. Because data are transmitted through the small core of the fiber patch cable, a very small amount of dirt or residue may significantly increase the connector’s attenuation and weaken the signal. Lack of applying proper patch cable cleaning procedures can directly impact the quality of the system’s performance.

General Tips for Patch Cable Cleaning

fiber patch cable cleaning is one of the most rudimentary and essential procedures to ensure network availability and reliability. The following lists some general suggestions when performing patch cable cleaning.

Point 1: Try to work in a clean area. Avoid working around heating outlets.

Point 2: Always keep dust caps on connectors and bulkhead adapters for as long as possible. Only remove the dust caps to clean the components prior to making a connection.

Point 3: Never touch the ferrule end face of a fiber optic connector. No matter what you do, you will leave contamination behind.

Point 4: Always clean connectors before inserting into an adapter. Use specialized cleaning tools or lint free pads and isopropyl alcohol to clean.

Point 5: Ferrules on the connectors/cables used for testing will get dirty by transference of contaminants from alignment sleeves in the bulkhead adapters, so test cables and adapters should be cleaned or replaced regularly when testing a large system.

Recommendations of Efficient Patch Cable Cleaning Tools

It is important to have proper tools to facilitate fiber patch cable cleaning job, which will greatly minimize the cleaning time and difficulty, making the cleaning process easier and more efficient. The commonly used patch cable cleaning tools are illustrated as follow.

a. Push-type cleaners (one-clike cleaners): this pen-shaped push-type cleaners feature an easy one-push action, which quickly and effectively cleans the end face of connectors on patch cables or through adapters without any alcohol or harsh chemicals. Always select the cleaner model for the connector type to be cleaned, 2.5mm for SC, FC and ST, and 1.25mm for LC and MU.

b. One-clike MTP/MPO cleaner: this cleaner is specifically designed to clean MTP/MPO connector end face on patch cables or in adapters. The unique design enables effective cleaning of either male (with pins) or female (without pins) connector, in fiber breakout modules and even networking gear like switches and routers.

c. Reel-type cleaners (cassette cleaners): they typically contain a lint free reel of cloth that is moved after each cleaning, always presenting a clean surface. Reel-type cleaners are safe patch cable cleaning options without the need for alcohol. Besides, they have refillable cleaning tapes, making them ideal for lab, assembly lines and field use.

d. Wipes and cleaning cards: there are a wide variety of patch cable cleaning wipes and cleaning cards for both field and manufacturing applications. They can be used either dry or with cleaning fluid to remove common contaminants for effective patch cable cleaning.

e. Cleaning swabs & sticks: Precisely designed, the mini foam clean swabs are made to serve various different patch cable cleaning and maintenance needs. Foam swabs are ideal for more precision cleaning where linting needs should be avoided. Swabs assist in cleaning small or hard to reach items.

Conclusion

For best optical performance, it is imperative that all fiber patch cable connections are clean and free of contaminants. An easy to use patch cable cleaning tool becomes a necessity for fiber technicians and installers. Even without specific training, field technicians and fiber installers can use a simple insertion and push motion to remove residue, debris and dust that can negatively impact network performance. So why not grab a patch cable cleaning tool to make your job easier?

Source: http://www.china-cable-suppliers.com/patch-cable-cleaning-tips-tools.html

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How to Integrate PoE to Your Network?

You may come across the situation when it is needed to install IP telephones, wireless access points or IP cameras to somewhere AC power outlets are not available. What would you do then? As extra power supply and wiring installation can be labor-intensified and time-consuming. The most feasible solution is to deploy PoE (Power over Ethernet)—a system standardized by IEEE802.3 that supplies low voltage power to Ethernet-enabled devices via the communication line. Here we illustrate how to upgrade your existing network to PoE.

PoE Network Explained

As its name suggests, PoE (power over Ethernet) is the technology to supply power directly via data cable, eliminating the need for additional electrical wiring. It makes network planning flexible and independent of switch sockets and cabinets, requiring no extra costs for excess wiring. Thus devices can be installed wherever structured Ethernet wiring is located, without the need for AC power outlets nearby.

Generally speaking, this technology enables network cables carry electrical power. Let’s take surveillance camera for example: it typically requires two connections when it is installed: a network connection to communicate with video recording and display equipment, and a power connection to deliver the electrical power to operate the camera. However, if this surveillance camera is PoE compatible, all we need is the network connection, as it can receive the needed electrical power from the cable as well.

Advantages of PoE Network

We know that powered devices such as surveillance cameras and wireless access points are often located in places where traditional power outlets are difficult to install or even not available. Under such circumstances, PoE functions to facilitate the use of wireless access devices, IP phones, surveillance cameras, the benefits of which is thus obvious.

The advantages of power of Ethernet features that Ethernet is always ubiquitous, hence it greatly increases mobility for end devices. And as no AC power involved, PoE is safer to use. Moreover, it simplifies installation and operation without the need for extra AC power wiring, keeping the cabling secure while not interfering with the network operation. This makes power over Ethernet a much securer, more reliable and cost-saving solution.

How to Integrate PoE to Your Network?

Before upgrading your existing network to PoE-enabled one. You’d better firstly make clear that there are two types of devices involved in this system: power sourcing equipment (PSE) and powered devices (PD). PD refers to a power over Ethernet compatible network end device equipped to accept power transmitted over structured Ethernet cabling. PSE provides DC power to PD. A PSE may be an endspan device or a midspan device. An endspan device typically is a network switch enabled to provide PoE power on each port. A midspan device is connected in-line to each end device and adds power to the line.

There generally exist three routes to achieve power over Ethernet to your network.

1. By PoE switch: a PoE switch is a network switch that with built-in power over Ethernet injection. Simply by connecting other network devices to the switch as normal, the switch will detect whether they are compatible to power over Ethernet and then enable power automatically. This kind of switches are available to suit all applications, from low-cost unmanaged edge switches with a few ports, up to complex multi-port rack-mounted units with sophisticated management.

2. Using midspan: a midspan enables PoE capability to regular network switches. With midspan, one can upgrade existing LAN installations to PoE. Midspan also provides a versatile solution where fewer ports are required. Upgrading each network connection to power over Ethernet is as simple as patching it through the midspan.

3. Via a PoE splitter: it is also feasible to upgrade powered devices (PDs) to power over Ethernet enabled ones by splitter. This splitter is patched into the camera’s network connection, and taps off the PoE power, which it converts into a lower voltage suitable for the camera.

Conclusion

The simplicity of combining signal and power in one Ethernet cable connection makes PoE technology an ideal solution for enterprise network. In this case, PSE can provide power to a wide variety of PD in areas with no access to AC power. Deploying this technology in your network will lead to a safe, reliable, and economical way to deliver consistent and dependable power to common networking devices.

Source: http://www.fiber-optic-solutions.com/integrate-poe-network.html

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Pre-Terminated Cabling System Pros and Cons

The past few years have seen the steady rise in the use of pre-terminated cabling system. This cabling solution is considered as the norm for some key areas, such as data centers and commercial office fit-outs. Then, what is pre-terminated cabling system in essence? And what we can expect from this cabling alternative? This article intends to clear the confusion about pre-terminated cabling system, by analyzing its definition as well as explaining the benefits and drawbacks of it.

What Is Pre-terminated Cabling System?

Pre-terminated systems are factory manufactured cables and modular components with connectors already attached, which usually have been tested, qualified and ready to plug and play in the network. They are available in both fiber and copper cabling. Pre-terminated systems offer unsurpassed advantages over conventional field installed system, which partially explains why the use of factory pre-terminated assemblies continues to grow, especially for data centers. Pre-terminated assemblies come in various forms, from trunk cables, connectorized fan-outs, attached or discreet cassette modules to cable bundles with protective pulling grips installed over the connectors at one end.

Where to Use Pre-terminated Cabling System?

At the beginning of the article, we’ve mentioned that pre-terminated cabling system commonly found its position in two fields: data centers and open offices. In response to the accelerated network capacity and application processing demands, data centers are expanding dramatically both in number and size. Which propel the advancement of alternative to improve the connectivity installation times and simplify the deployment for reliable and rugged cabling systems. The open office also benefits from the pre-terminated cabling system which can be quickly reconfigured to match the moves, adds and changes. Pre-terminated cabling system is expected to spread its influence in these types of scenarios.

Pros and Cons of Pre-terminated Cabling System

We all know that one size does not fit all, so there are some serious pros and cons one must take heed of when dealing with pre-terminated cabling system.

Benefits of Pre-terminated Cabling System

Once used properly, pre-terminated solutions can bring a raft of benefits to cable installers and end-users.

Cost Saving: Although pre-terminated assemblies may have a higher initial cost since they include the factory termination time, the savings it provides go beyond the expense.

Time Saving: Pre-terminated system helps to save time in various ways. Since the assemblies are factory terminated, they require minimal engineering or assembly work on site. Meanwhile, pre-terminated assemblies also save testing and troubleshooting time. Also, pre-terminated assemblies are factory terminated which reduce many of the problems that may occur with field terminations.

Labor Saving: With pre-terminated assemblies, you don’t need as many on-site engineers pulling cables in and terminating them. As the pre-terminated links have been pre-tested, this vastly mitigates the need for troubleshooting and retesting.

Space Saving: For any data centers, the available space is always precious. Data center managers will embrace anything that contributes to promoting space utilization. With massive optical fibers being adopted in the data center to speed data transmission, pre-terminated assemblies offer much higher density and flexibility for data center upgrades.

Cooling Advantages: Heating and cooling issues matter significantly especially in high density network environment. Pre-terminated cabling system allows much more flexibility in configuration for installers working in compact space. Optimized airflow can be achieved by using pre-terminated assemblies such as trunk cables and plug and play cassettes, in conjunction with high density frames.

Security Benefits: Security is always put in a paramount place in data centers. And pre-terminated cabling system does offer numerous security benefits. With pre-terminated solution, less manpower is required for the installation, making it simpler to manage “contract personnel”. While less specialist skills required to install pre-terminated assemblies, enterprises can even use their own team to do the job.

Drawbacks of Pre-terminated Cabling System

For all its advantages, pre-terminated cabling system is something of a double-edged sword, which means it certainly has some downsides. One drawback concerning pre-terminated cabling solution is the accuracy measurement required. Three is no turning up with cable assemblies that are too short or excessively long, and there is no containment space to store the excess cables. So accurate site surveys are rather essential.

Conclusion

With the benefits absolutely outweigh the drawbacks, pre-terminated cabling system provides an increasingly popular way of delivering a project in a more timely and cost effective manner. However, one should always carry out a comprehensive planning and site survey before installation to assure you can exactly benefit from pre-terminated cabling solution.

Source: http://www.china-cable-suppliers.com/pre-terminated-cabling-pros-cons.html