Structured Cabling or Unstructured Cabling Solutions

40G network has replaced 10G lately and used worldwide, under this circumstance, 40G equipment like 40G transceivers and QSFP+ cables are required. Plan the cabling system in advance is the prerequisites to the designing of network system. The goal is to address current network requirements as well as accommodate future growth. There are two types of cabling solutions for 40G—structured cabling and unstructured cabling. This article will mainly introduced these two cabling solutions to you.

What Is Structured Cabling?
Structured cabling specified by the EIA/TIA TR42 committee, is the standardized architecture and component for communication cabling. In a structured cabling system, a series of patch panels and trunks are used to create a structure that allows for hardware ports to be connected to a patch panel at the top of the rack (see in Figure 1). A structured cabling system provides a flexible cabling plan to address the commonly performed tasks of moving, adding, and changing the infrastructure as the network grows.

What Is Unstructured Cabling?
Unstructured cabling occurs when optical links are deployed point to point or device to device with no patch panels installed in the link. In this situation, cabling pathways become congested with an entangled mess of two-fiber optical patch cords (Figure 2). Likewise, routing new patch cords in ceiling or floor trays all the way across a data center each time a new device is deployed is extremely inefficient.

Structured or Unstructured Cabling System
As noted before, the difference between structured and unstructured cabling lies in the installation of patch panels. A good analogy for this is the electrical wiring in your home. When connecting appliances and devices, you require only a 5-foot connection to the closest electrical outlet. However, without an electrical outlet, all appliances would have to connect directly to the breaker or panel, requiring a cable of 200 feet or more. This approach would be inefficient and would become unmanageable as you add multiple appliances and devices throughout the home.

Unstructured cabling like above point to point connectivity method can’t satisfy people’s needs any more. Because it may appear some mistakes in an unorganized messy cabling infrastructure. Remove a single cable from a large tangled mess can cause stress on the other cables. This stress can lead to network errors in the hardware that are very difficult to trace. Therefore, structured cabling becomes a necessity as the infrastructure grows and as constant moves and changes reinforce the need for a reliable network that is also easy to troubleshoot.

40G Structured Cabling Components
Laser-optimized multimode fiber, compared with single-mode fiber has proven itself to be the cost-effective cabling methods for high-data-rate system like 40GbE network, which has become the dominant fiber choice. Optimized for 850-nm VCSEL transceivers, these 50-micron fibers (especially OM3 and OM4) provide optimum technical and economic solution and become the dominant structured cabling options for today’s data centers. QSFP+ transceiver (typically with a 12-fiber MTP connector) is the dominant transceiver used for 40G applications. Other essential components for 40G structured cabling include MTP trunk cables, MTP-LC harness/breakout cables, LC or MTP patch cables, MTP-LC cassette modules, MTP adapter panels and MTP rack mount holders.

Conclusion
When deploying a network system, it is important to plan a cabling system in advance. Structured cabling uses fiber termination connector panels that are connected through permanent links of optical cabling, which is more popular than unstructured cabling. Fiberstore supplies a wide range of fiber optic transceivers and MTP/MPO assemblies such as MPO/MTP trunk cables, harness cables, cassette module and adapters. We also provide cost-effective 40G products including 40G QSFP and 40G cables. To satisfy your unique demands, we support custom or OEM service as well. For more information, please contact us directly

Reference:
http://www.cisco.com/c/en/us/products/collateral/switches/nexus-9000-series-switches/white-paper-c11-729908.html

Multi-mode or Single-mode Optics for 40GbE Network

To back the changing and fast-growing bandwidth demands of data center, in 2010, the IEEE ratified 40 Gigabit and 100 Gigabit standards, known as IEEE 802.3ba. 40G and 100G Ethernet can be deployed using the same cabling systems today. Both single-mode (SMF) and multi-mode (OM3,OM4) were approved to be utilized in the standard. Multi-mode deploys parallel optics with MPO/MTP interconnects while single-mode fiber will employ serial transmission and use LC or SC connectors. Which cabling options designers should choose for their infrastructure. This article today will provide some practical suggestions to help you make a wise selection. Table 1 shows the comparison between SMF and MMF for 40/100 GbE Implementations.

40GbE Over Multi-mode Fiber
40GbE and 100GbE over multi-mode optics use parallel optics at 10Gbps lasers, simultaneously transmitting across multiple fiber strands to achieve high data rates. Because of the multi-lane nature of these optics, 40GbE multi-mode optics use a different style of fiber cabling, known as MPO or MTP cabling. An MPO/MTP cable presents 12 separate strands of multi-mode fiber in a single ribbon cable. Just as 10GbE optics over multi-mode fiber, an OM3 or OM4 grade MMF is needed to cover longer distances for 40G network.

OM3 and OM4 MMF are laser-optimized fiber with a core size of 50/125 micron. These 50-micron fibers are optimized for the 850nm transmission of VCSEL-based transceivers. These two fibers have different bandwidths, which results in different achievable lengths for the same transceivers. OM4 fibers, according to the TIA-492AAAD, have higher network reliability and increased design flexibility allowing links with a reach of 150 meters. The IEEE 802.3ba standard specified OM3 fiber with a maximum reach of 100 meters. Take Cisco QSFP-40G-SR4 QSFP+ as an example, it can support a distance of 100m and 150m over OM3 and OM4, respectively. The following image shows a 40G-SR4 and 40GBASE-LR4 QSFP+.

Since we can deploy both OM3 and OM4 MMF for our 40G infrastructure, which one is more suitable? In fact, some senior engineers say that installing either OM3 or OM4 cabling in the data center largely depend on length requirements. They determined that OM4 fiber would substantially extend the reach of next generation networking within the data center and it is able to achieve this greater reach because of its greater EMB over OM3 fiber. OM4 optical fiber enables 40/100G Ethernet to reach an additional 60% of the links in the core-to-distribution and in the access-to-distribution channels when compared to OM3. This should lead to faster market acceptance of 40G/100G Ethernet and OM4 fiber.

40GbE Over Single-mode Fiber
40GBase-LR4 optics use the same multi-lane technology as SR4 optics using four strands for transmit and four strands for receive. But with one exception. Instead of using a single fiber strand for each lane, WDM technology is used to multiplex all four transmit lanes onto one strand of fiber and all four receive lanes onto another single strand of fiber, allowing any existing single-mode fiber installation to be used. Because of this, standard LC (for QSFP modules) or SC (for CFP modules) connections are used, allowing for an easy upgrade from a 10GbE connection. The channel cost for 40GBASE-LR4 is much higher than SR4 optics, which is the main factor that limits its popularity. However, 40GBASE-LR4 like Cisco QSFP-40G-LR4 can reach up to 10km.

Conclusion
After going through this article, do you have any idea of choosing which cabling for your 40G network. If you have tight budget and cover a short transmission distance, laser-optimized multi-mode cabling would be the prefect choice. But if you prefer to deploy a high-density long-reach network, single-mode cabling will suit you better. Fiberstore manufactures a large variety of 40G transceivers and cables. You can find what you need here. Please contact us if you are interested.

40-Gbps Parallel and Bidirectional Transceiver

With speed in data center changing from 10- to 40-Gbps and eventually to 100-Gbps, mobile and virtualized workloads, cloud applications, big data and heterogeneous devices are all demanding previously unimagined capacity and performance from servers and data center fabric. High-capacity optical technology and cabling infrastructure are required to support those servers and applications for 40-Gbps upgrading. Today’s article will mainly introduce pluggable optical Enhanced Quad Small Form-Factor Pluggable (QSFP+) modules, especially Bidirectional and parallel QSFP+ transceivers.

Brief Introduction to Optical Transceiver
The transceiver is an electronic device comprising both a transmitter and a receiver in the same circuity. This optical transceiver receives an electrical signal, converts it into a light signal, and launches the signal into a fiber. It also receives the light signal, from another transceiver, and converts it into an electrical signal. It is commonly known as GBIC, SFP, SFP+, XFP, CFP and QSFP+. The QSFP+ transceiver is the dominant transceiver form factor used for 40 Gigabit Ethernet applications. In 2010 the IEEE standard 802.3ba released several 40-Gbps based solutions, including a 40GBASE-SR4 parallel optics solution for MMF (FTL410QE2C is compatible Finisar 40GBASE-SR4 QSFP+ MMF transceiver with a link length of 150m). Since then, several engineered solutions have been released, including 40GBASE-CSR4, which is similar to 40GBASE-SR4 but extends the distance capabilities. Another solution is a bidirectional 40-Gbps transceiver that uses a two-fiber LC optical interface.

Comparison of 40GBASE-SR4 Parallel Transceiver and Bidirectional Optical Transceivers 
Parallel optical transceivers differ from traditional fiber optic transceivers in data center is simultaneously transmitted and received over multiple fibers. Used for 40GBASE-SR4 and 40GBASE-CSR4, this transceiver has 10-Gbps electrical lanes that are mirrored in the optical outputs and thus require eight fibers with an MTP connector interface. Each fiber either transmits (Tx) or receives (Rx) 10-Gbps traffic at a single wavelength. Figure 1 shows the electrical and optical lanes diagram of 40GBASE-SR4 QSFP+ transceiver.

Bidirectional optical transceivers used for 40GBASE-SR-BD have the same 10-Gbps electrical lanes, which are then combined in the optical outputs, thus requiring two fibers with an LC connector interface. Each fiber simultaneously transmits and receives 20-Gbps traffic at two different wavelengths. Figure 2 shows a electrical and optical lanes diagram of bidirectional optical transceiver.

From the above images, we can easily see some differences between Bidirectional and parallel optical transceiver. This two-fiber 40-Gbps Bidirectional (BiDi) multimode solution uses two different transmission windows (850 nm and 900 nm) that are transmitted bidirectionally over the same fiber, which will allow the use of same cabling infrastructure for 40 Gigabit Ethernet as was used for 1 and 10G Ethernet application. While the parallel multimode optical transceiver operates at a wavelength of 850nm. In additional, the connector type was converted from the traditional 2-fiber LC duplex connector to a 12-fiber MTP connector.

Cabling Options for Parallel and Bidirectional Optical Modules
Choosing which type of fiber optical cable for your infrastructure is essential. As noted before, 40GBASE-SR4 multimode parallel optical transceiver uses eight fibers to transmit four duplex channels each at 10 Gigabit Ethernet. Parallel optical transceiver uses MTP 12-fiber trunk cable but only 8 of 12 fibers is used. There are several basic cabling options for parallel optics connectivity. I will generally introduce three solutions to you. One approach is to ignore the unused fibers and continue to deploy 12 fibers. Another approach is to use a conversion device to convert two 12-fiber links into three 8-fiber links. Figure 3 summarizes these three cabling solutions for 40G connectivity.

As for the pluggable Bidirectional transceiver, it has the same QSFP+ format as the existing 40GBASE-SR4 transceiver. Therefore, the same switch line card with QSFP+ ports can support either parallel optics 40GBASE-SR4 or bidirectional optics 40GBASE-SR-BD solutions. Thus, when directly connecting a 40 Gigabit Ethernet bidirectional transceiver to another bidirectional transceiver, a Type A-to-B standard LC duplex patch cord can be used. This reverse fiber positioning allows a signal to be directed from the transmit position on one end of the network to the receive position on the other end of the network. However, this type of direct connectivity is suggested only within a given row of cabinets.

Conclusion
40-Gbps performance is no longer a myth, but a truth that has already facilitated people's daily life. When transitioning from 10 to 40 Gigabit Ethernet, extended 40 Gigabit Ethernet link distances, which match the distances at 10 Gigabit Ethernet, can be achieved by parallel optics transceivers. And as to 40 Gigabit Ethernet bidirectional transceivers, no changes to the cabling infrastructure are required, which is a huge cost saving. Fiberstore offers a large variety of 40-Gbps parallel optical transceivers that are fully compatible with major brand like Finisar QSFP+. For more detailed information about our devices, please contact us directly.

Reference:
http://www.cisco.com/c/en/us/products/collateral/switches/nexus-9000-series-switches/white-paper-c11-729908.html

How to Minimize the limitations on the Transmission Distance

Transmission distance is the NO.1 factor that designers would take into account when deploying network because the exact transmission distance that fiber optic can support is usually limited by many factors. How to avoid this situation? Is there a method that can help us to achieve long transmission distance? This article today will pay attention to the factors that limit optical transmission distance and provide some practical solutions accordingly.

Optical Cable Type
The maximum transmission distance of fiber optic cable (single-mode or multi-mode fiber) is typical limited by dispersion. Multi-mode transmission is affected by the modal dispersion, while single-mode fiber is limited by chromatic dispersion. The core of the single-mode fiber optic is much smaller than that of multi-mode fiber. That’s why single-mode can transmit over longer distance than multi-mode fiber. Most designers should attach importance to review the specifications and limitations of transceivers and have them work optimally in their devices. Then it is highly recommended that we use multi-mode fiber optic transceivers for shorter distances and single-mode fiber for long distance transceivers. Take QFX-QSFP-40G-SR4 as an example, it is the compatible Juniper 40GBASE-SR4 QSFP+ transceiver that operates over multi-mode fiber. Although our application may call for an long reach, we can only use multi-mode fiber on this module for a distance of 150m. If you use an single-mode fiber on this transceiver, it may cause an error.

Light Source of Fiber Optic Transceiver
Optical signals must be converted into electronic signals over the optical transceiver because most of the devices are electric based. And the conversion between them is largely depend on a LED (light emitting diode) or a laser diode inside the optical transceiver. Fabry Perot (FP) laser, Distributed Feedback (DFB) laser and Vertical-Cavity Surface-Emitting (VCSEL) laser are the common type of light source inside the transceiver module that may have an impact on optical transmission distance. Table 1 present a comparison between these light sources, which would be a factor that designers should take into account when picking an optical transceiver to achieve long transceiver distance.

Splice and Optical Connectors
The signal loss can be caused when passing through fibers or connector, which will largely affect the transmission distance. Fusion splicing is the method of joining two optical fibers end-to-end using heat. Alternatives to fusion splicing include using optical fiber connectors or mechanical splices both of which have in general higher insertion losses, lower reliability and higher return losses than fusion splicing. Network designers nowadays choose to use fusion splicing because the goal of such a way that optical signal passing through the fibers is not attenuated or reflected back by the splice. In other word, fusion splicing will have less effect in the transmission distance that fiber optic cable can support. Here are some tips for fusion splicing that may help you.

1. Clean the fiber
2. Stripping the coating off the two fibers that will be spliced together
3. Cleaning of the stripped fiber
4. Each fiber must be cleaved so that its end-face is perfectly flat and perpendicular to the axis of the fiber
5. Aligning of two end-faces of the fibers. This is normally done by the splicing machine by means of: fixed V-groove, optical core alignment, cladding alignment or local injection and detection of light (LID)
6. The two fibers are fused together
7. Check mechanical strength of the splice (normally done by the splicing machine)
8. The bare fiber area around the splice is protected with a splice protector and use the same batch of high quality bare fiber on a route
9. Choose installers who have adequate training and rich experience in fiber connection

As noted above, the optical transmission distance is affected by a variety of factors, like fiber optic cable type, light source of transceiver, and splices and connectors. Frequency of transmission and bandwidth should also be considered to minimum the limitations on the transmission distance. I hope all the suggestions that I have provided above can help you to achieve long transmission distance. Fiberstore offers a variety of high-quality fiber optic cable and optical transceiver modules (like the popular 40G QSFP) that are fully tested. Meanwhile, components like repeater and optical amplifiers are also useful to support the long distance transmission. If you have any interest in our products, please contact us directly.

Reference:
http://www.cisco.com/c/en/us/products/collateral/interfaces-modules/transceiver-modules/white_paper_c11-463677.pdf

How to Select the Basic Materials of the LAN

Installing or designing network may pose a challenge as there are multiple optical solutions that meet the same specification or requirement. But by understanding the basic optical components and the specific performance requirements, you will be able to generate a cost-efficient bill of materials for your project. Thus before picking any products for your infrastructure, you must read this article.

Fiber Type
There are two basic fiber types: single-mode and multi-mode. Multi-mode fiber is graded by OM (optical multi-mode), the higher the OM grade, the better bandwidth performance you can expect. And it comes in both 50μm and 62.5μm core sizes with 50 μm multi-mode available in both standard (OM2) as well as a laser-optimized version (OM3/OM4). Single-mode are graded by OS (optical single-mode) and can run at OS1 and OS2, as described in TIA-568 C.3. Keep the consistency within your network is critical for long-term performance, therefore you shouldn’t mix new fiber type or performance with your old plant.

In addition, the cost of the components should be considered. The transceiver associated with single-mode fiber are more expensive than those for multi-mode. For example, the price of JG661A (compatible HP 40GBASE-LR4/OTU-3 QSFP+ transceiver) is much higher than JG325B (compatible HP 40GBASE-SR4 QSFP+ transceiver). The decision must be made to balance the performance and the cost. Single-mode system will provide for future expansion, yet multi-mode fiber is only for today and the near future. To sum up, single-mode fiber operate better at long reach while multi-mode fiber is ideal for short reach, choosing single-mode or multi-mode depends on your networks needs.

Termination Method
Deciding on a termination methods is typical affected by many factors. If your biggest concern is time, no epoxy/no polish connectors are probably your best choice. The fiber end faces are factory polished and easily installed with a tool kit. This types of termination method allows you to perform terminations quickly, but the cost is usually higher than that of epoxy and polish connector.

If your biggest concern is cost. epoxy and polish connectors might be a good fit because of their low initial price. This type of termination need considerable time to learn how to properly hand-polish connectors that meet specification, and it requires a large workspace to lay out the polishing papers, polishing pucks, epoxy, etc. If your work environment or network condition is not allowed, it is advisable not to select this method.

Fusion Splicer or Optical Connector
Keep in mind that whether to choose fusion splicing or a connector for your network will always need an experienced installer under adequate training. Fusion splicer, as we all know, is very expensive. If your company do not own one, it can be a large investment to make and you need to order the correct splice tray for your hardware and heart-shrinks to keep your splices intact. But if you already have a fusion splicer, fusion-spliced pigtails might be the right choice for you that can provide high quality results and easy to use in areas. The following picture shows a Fujikura FSM-80S Core Alignment Fusion Splicer.

Specifications, density, electronics interfaces and existing plant often drive connector choices. LC connector is favored for its maximum density and room-saving. It is also available in duplex from, which allows you to manage polarity by simply reversing the connector via a duplex clip. SC connectors feature an easy push/pull locking mechanism and are available in simplex and duplex forms. ST compatible connectors have a spring-loaded bayonet locking system that helps them stay in place but are only available in simplex versions.

Hardware
To determine the type of hardware you need, take into consideration the space that will be utilized for the network. If you are installing inside of a closet or other cramped quarters and need low density, wall mountable hardware is the best selection as it does not take up a lot of room. If racks are already in place, or if there is enough room to install them, rack-mount hardware is the best selection because it is sturdy and easy to access.

Additional Information
Designing a network may be a big project as you should take a lot of things into consideration. To make sure the high performance of you network, please think about all the aspects that I have written in this text. What’s more, there are three basic categories for cable: indoor, outdoor and indoor/outdoor. The types of cables you have to choose for your infrastructure depend on where the cables will be run. Fiberstore supplies a whole variety of optical equipment including fiber optical cables, optical transceivers, fusion splicer and optical connectors. Come to us to help your data transmission initiatives for future proof.