Category: Fiber Transceivers

Optical transceivers, Active Optic Cables, data center switches, and cable management in data centers.

1000BASE-X SFP Modules Overview

A continuous stream of manufacturing process improvements and product innovations has given fiber optical system several advantages, like longer distance reach, larger data-carrying capacity, greater bandwidth and lower power consumption. Among these fiber optical product innovations, hot-plable transceiver modules should come to the central point with their unique designs. They have been constantly designed, and finally been reinvented as hot-plable modules along with the optical technological advances. These small, hot-plable serve as the key components in accommodating the demands of higher port density and more networking flexibility.
Transceiver modules come into various types: SFP (small form-factor plable), SFP+ (small form-factor plable plus), QSFP+ (quad small form-factor plable plus), etc. This article mainly introduces SFP transceiver modules which are widely applied in Gigabit Ethernet (GbE) applications, with the focus on several 1000BASE-X interface types, including 1000BASE-SX, 1000BASE-LX, 1000BASE-EX, and 1000BASE-BX10-D/U.
Features and Benefits
1000BASE-X SFP modules provide a wide range of form factor options for enterprise and service provider needs. They are designed with the following features and benefits:
Hot swappable to maximize uptime and simplify serviceability;
Flexibility of media and interface choice on a port-by-port basis, so you can “pay as you populate”;
Sophisticated design for enhanced reliability;
Supports digital optical monitoring (DOM) function;
1000BASE-X SFP Interface Types
1000BASE-SX SFP
1000BASE-SX SFP, compatible with the IEEE 802.3z 1000BASE-SX standard, operates on legacy 50Ľm multi-mode fiber (MMF) links up to 550m and on 62.5Ľm Fiber Distributed Data Interface (FDDI)-grade MMFs up to 220m. Take DEM-311GT for example, Fiberstore compatible D-Link 1000BASE-SX SFP is able to realize 550m link length through OM2 MMF with duplex LC.
1000BASE-LX SFP
1000BASE-LX SFP, compatible with the IEEE 802.3z 1000BASE-LX standard, is specified to support link length of up to 10km on standard single-mode fiber (SMF), to 550m on MMFs. When used over legacy MMF, the transmitter should be coupled through a mode conditioning patch cable. The laser is launched at a precise offset from the center of the fiber which causes it to spread across the diameter of the fiber core, reducing the effect known as differential mode delay which occurs when the laser couples onto only a small number of available modes in MMF.
1000BASE-EX SFP
1000BASE-EX, sometimes referred to as LH, is a non-standard but industry accepted standard which works on standard SMF with fiber link spans up to 40km in length. For back-to-back connectivity, a 5-dB inline optical attenuator should be inserted between the fiber optic cable and the receiving port on the SFP at each end of the link. 1000BASE-EX SFPs (eg. GLC-EX-SMD) run on 1310nm wavelength lasers, and achieves 40km link length.
1000BASE-BX10-D/U SFP
The 1000BASE-BX-D and 1000BASE-BX-U SFPs, compatible with the IEEE 802.3ah 1000BASE-BX10-D and 1000BASE-BX10-U standards, operate on a single strand of standard SMF (figure shown below). A 1000BASE-BX10-D device is always connected to a 1000BASE-BX10-U device by a single strand of standard SMF with an operating transmission distance up to 10km.
The communication over a single strand of fiber is accomplished by separating the transmission wavelength of the two devices (figure shown above): 1000BASE-BX10-D transmits a 1490nm channel and receives a 1310nm signal, whereas 1000BASE-BX10-U transmits at a 1310-nm wavelength and receives a 1490-nm signal. In this figure, the wavelength-division multiplexing (WDM) splitter is integrated into the SFP to split the 1310nm and 1490nm light paths.

10GbE Interconnect Solutions Overview

New sophisticated networking services, coupled with the increase of Internet users push the Internet traffic to an even higher point, driving the need for increased bandwidth consequently. One Ethernet technology—10 Gigabit Ethernet (GbE) is adequate for such bandwidth demand, and has become widely available due to the competitive price and performance, as well as its simplified cabling structure.
Several cable and interconnect solutions are available for 10GbE, the choice of which depends on the maximum interconnect distance, power budget and heat consumption, signal latency, network reliability, component adaptability to future requirements, cost. Here cost includes more than what we call the equipment interface and cable cost, but more often the labor cost. Thus, choosing a 10GbE interconnect solution requires careful evaluation of each option against the specific applications. This text aims to introduce two main 10GbE interconnect solutions: fiber optics and copper.
Fiber Optics Solution
Fiber optic cables include single-mode fiber (SMF) and multi-mode fiber (MMF). MMF is larger in diameter than that of single-mode, thus portions of the light beam follow different paths as they bounce back and forth between the walls of the fiber, leading to the possible distorted signal when reach the other end of the cable. The amount of distortion increases with the length of the cable. The light beam follows a single path through thinner single-mode cable, so the amount of distortion is much lower.
The typical 10GBASE port type that uses MMF is 10GBASE-SR which uses 850nm lasers. When used with OM3 MMF, 10GBASE-SR can support 300m-connection distances, and when with OM4 MMF, 400m link length is possible through 10GBASE-SR SFP+ transceiver.
10GBASE-LR (eg. E10GSFPLR), 10GBASE-ER and 10GBASE-ZR are all specified to work via SMF. SMF can carry signals up to 80km, so it is more often used in wide-area networks. But since SMF requires a more expensive laser light source than MMF does, SMF is replaced by MMF when the required connection distance is not so long.
Copper Solution
10GBASE-CX4, SFP+ Direct Attach (DAC) and 10GBASE-T are all specified to operate through copper medium.
10GBASE-CX4
Being the first 10GbE copper solution standardized by the IEEE as 802.3ak in 2002, 10GBase-CX4 uses four cables, each carrying 2.5gigabits of data. It is specified to work up to a distance of 15m. Although 10GBase-CX4 provides an extremely cost-effective method to connect equipment within that 15m-distance, its bulky weight and big size of the CX4 connector prohibited higher switch densities required for large scale deployment. Besides, large diameter cables are purchased in fixed lengths, causing problems in managing cable slack. What’s more, the space isn’t sufficient enough to handle these large cables.
SFP+ DAC
SFP+ Direct Attach Cable (DAC), or called 10GSFP+Cu, is a copper 10GBASE twin-axial cable, connected directly into an SFP+ housing. It comes in either an active or passive twin-axial cable assembly. This solution provides a low-cost and low energy-consuming interconnect with a flexible cabling length, typically 1 to 7m (passive versions) or up to 15m (active versions) in length. Below is the SFP+ to SFP+ passive copper cable assembly with 1m length, 487655-B21, a HP compatible 10GbE cabling product.
10GBASE-T
10GBASE-T, known as IEEE 802.3an-2006, utilizes twisted pair cables and RJ-45 connectors over distances up to 100m. Cat 6 and Cat 6a are recommended, with the former reaching the full length at 100m, and the latter at 55m. In a word, 10GBASE-T permits operations over 4-connector structured 4-pair twisted-pair copper cabling for all supported distances within 100m. Besides, 10GBASE-T cabling solution is backward-compatible with 1000BASE-T switch infrastructures, keeping costs down while offering an easy migration path from 1GbE to 10GbE.

Which Cabling Solution is Better for Your Data Center

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Although cabling only represents less than 10 percent of the overall data center network investment, it outlives most network elements and treated as the most difficult and potentially costly component. With the datacenter cabling ranging from 1G to 10G, 10G to 40G and even to 100G, more complex cabling is required to ensure a good service or scalability for troubleshooting. In practice, there is no exact solution that will meet all of the cable management needs. However, two kinds of cabling systems can be applied—unstructured system and structured system. Just follow the guidelines and illustration highlighted in the article will go a long way to ensure you with the information required for the successful deployment of a cabling infrastructure in your data center.
Unstructured Cabling System
Unlike the structured cabling system with a managed patch panel, a unstructured cabling only occurs when optical links are deployed point to point or device to device without installing patch panels. In this situation, cabling pathways become congested with an entangled mess of two-fiber optical patch cords. 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.
And this entanglement will bring difficulties in routing new patch cords in ceiling or floor trays all the way across the data center whenever a new device is deployed. That greatly influences work efficiency. What’s more, this system causes the overheating of data centers especially around the racks where cable clutter occurs.
Structured Cabling System
Structure cabling emerged as a way to better manage larger data center solution is a big step for the development of optical technology. Structured cabling system is a flexible, reliable and highly efficient for moving, adding and changing the infrastructure as the network grows. This kind of system requires additional investment on pre-terminated MPO cabling such as patch panel to create the cabling infrastructure.
Compared with the unstructured cabling, structured cabling architecture is generally easier to manage and more scalable. And, due to the use of trunked or shared horizontal cabling, it often carries a smaller cable footprint than direct-attach cabling. However, the flexibility of structured cabling presents potential downsides, including cost and link-loss budget. Nevertheless, existing large data centers will likely retain their structured cabling infrastructures, particularly for long-reach, zone-to-zone applications, where it generally remains the more practical choice. The following part will introduce 40G structured cabling solutions.
40G Structured Cabling Solutions
As noted before, structured cabling solutions allow for high consolidation of cabling into a compact patch panel, cabling and connectivity. The traditional duplex multimode SC or LC connections do not support 40G data rate standards, today the MPO technology is commonly found in cassette-based data center installation allowing for easy management and maintenance. Below are cabling solutions of 40G for cable management configurations with the use of MPO patch panel.
One method (seen in the above picture) uses MTP-LC harnesses to transition the MTP connector to LC leads through the use of fiber enclosure loaded with 4 fiber adapter panels (12xMTP Key-up/Key-down). This 12-fiber MTP to LC harness assembly breaks out 4 x LC uniboot legs connecting the SFP+ ports. The lengths of LC harness legs can be customized to adapt to different situations. But this often results in messy cable management. The other method uses MPO/MTP trunk cable and fiber enclosure loaded with 4 MTP high density cassettes (2 x MTP-12 to Duplex LC/UPC 10G OM4) to realize the interconnection. This 96-fiber 1RU rackmount fiber enclosure connects fiber patch cables LC to LC and MTP trunk cable. This method is specially used when the 4xLC ports are not located in close proximity on a single device or are being split between multiple devices. Because it’s more manageable to land the MTP trunk cables into fiber enclosure with individual LC ports for 4xLC patch cables.
Conclusion
Choose the most suitable cabling to support present and future network technology is essential for the long-standing performance of the data center. Structured cabling using an MTP cabling infrastructure is suitable for current 10 Gigabit Ethernet environments while maintaining protection for 40 Gbps environments and beyond. Compared with unstructured cabling, it might be a better solution for you. Except for the right knowledge of a structure cabling, the right tools, patience and discipline are also the key factors that will attribute to the masterpiece of your cable management in data center.

Four Basic Elements in a WDM System

by http://www.fiber-mart.com

We know that fiber can carry more data over long distances than any other physical medium. That makes fiber a very precious material. And how to make the most use of your fiber plant becomes a question. So there comes Wavelength Division Multiplexing (WDM).
Why Should We Deploy WDM ?
WDM can multiply your fiber capacity by creating virtual fibers. The foundation of WDM lies in the ability to send different data types over fiber networks in the form of light. By allowing different light channels, each with a unique wavelength, to be sent simultaneously over an optical fiber network, a single virtual fiber network is created. Instead of using multiple fibers for each and every service, a single fiber can be shared for several services. In this way WDM increases the bandwidth and maximizes the usefulness of fiber. Since fiber rental or purchase accounts for a large share of networking costs, substantial costs can be saved through the application of WDM. Next I will introduce to you the basic four elements in the form of a WDM system.
The Core Technology of WDM System
Generally speaking, a WDM system consists of four elements, that are transceiver, multiplexer, patch cord and dark fiber. The following text will explain them to you respectively.
Fiber Optic Transceivers. Optical transceivers are wavelength-specific lasers that convert data signals from SAN or WAN to optical signals that can be transmitted into the fiber. Each data stream is converted into a signal with a light wavelength that is an unique color. Due to the physical properties of light, channels cannot interfere with each other. Therefore, all WDM wavelengths are independent. Creating virtual fiber channels in this way can reduce the number of fibers required. It also allows new channels to be connected as needed, without disrupting the existing traffic services.
Optical Multiplexers. The WDM multiplexer, sometimes referred to as the Mux, is the key to optimizing, or maximizing, the use of the fiber. The multiplexer is at the heart of the operation, gathering all the data streams together to be transported simultaneously over a single fiber. At the other end of the fiber the streams are demultiplexed and separated into different channels again.
Patch cord. The transceiver transmits the high-speed data protocols on narrow band wavelengths while the multiplexer is at the heart of the operation. The patch cable is the glue that joins these two key elements together. LC fiber patch cables are popular, which connect the output of the transceiver to the input on the multiplexer.
Dark fiber. A requisite for any WDM solution is access to a dark fiber network. The most common way of transporting optical traffic over an architecture is by using a fiber pair. One of the fibers is used for transmitting the data and the other is used for receiving the data. This allows the maximum amount of traffic to be transported. At times only a single fiber is available. Because different light colors travel on different wavelengths, a WDM system can be built regardless. One wavelength is used to send data and a second one to receive it.
Conclusion
WDM has revolutionized the cost of network transport. Thanks to WDM, fiber networks can carry multiple Terabits of data per second over thousands of kilometers with a low cost that is unimaginable less than a decade ago. At FS, we offer a comprehensive portfolio of WDM transmission modules to support the network applications of enterprise and service provider customers.

Linux Foundation starts OPEN-O Project for open source orchestrators

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The Linux Foundation has used the Mobile World Congress this week in Barcelona to announce its intent to form the OPEN-Orchestrator Project (OPEN-O). The project will seek to develop the first open source software framework and orchestrator to enable software-defined networking (SDN) and network function virtualization (NFV) operations.
The foundation, which is also a major force behind such SDN/NFV-related projects as OpenDaylight and ONOS, says initial supporters of OPEN-O include Brocade, China Mobile, China Telecom, DynaTrace, Ericsson, F5 Networks, GigaSpaces, Huawei, Infoblox, Intel, KT, Red Hat, Raisecom, Riverbed, and ZTE. Other interested parties are welcome to participate as well, according to the foundation.
The Linux Foundation says the project is necessary because, while SDN and NFV have begun to enable autonomous, real-time telecom operations, many operational support systems (OSS) based on proprietary software are getting in the way. The result is fragmented technologies and interoperability issues. As an open source orchestration framework would enable speed SDN and NFV implementation, the thinking goes, as well as accelerate multi-vendor integration, service innovation, and network agility.
As with other Linux Foundation projects, OPEN-O governance could include a Technical Steering Committee and an End User Advisory board to ensure alignment of needs between the technical and end user communities. Project members expect to create a development and testing platform as well as build and support an open source developer community.
“Operators are now facing the transformation of capabilities to provide user-centric services, from connectivity-oriented service to integrated cross-domain, cross-layer and cross-vendor services. With the introduction of SDN and NFV, the networks are becoming increasingly automatic and service-oriented, inspiring much more creation and exploring to build up a rich and flat ecosystem,” explained Shen Shaoai, China Telecom’s deputy general manager of the Technology Department. “OPEN-O will set up the world’s first SDN and NFV unified orchestrator platform. China Telecom is expecting this platform can play a significant role in the development of SDN/NFV. China Telecom is willing to work together with other operators and partners to promote the collaborative innovation and look forward to a bright future of SDN and NFV.”

What Are SFP Ports Used For?

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If you know Cisco SFP Modules, you must know the SFP Ports. If you didn’t know what are SFP modules or SFP ports, you can read this article, which can tell you what are SFP ports on a Gigabit Switch used for?
Cisco SFP Modules, the industry-standard Cisco Small Form-Factor Pluggable Gigabit Interface Converter, links your switches and routers to the network.
SFP sockets are found in Ethernet switches, routers, firewalls and network interface cards. It interfaces a network device motherboard (for a switch, router, media converter or similar device) to a fiber optic or copper networking cable.
In many cases, SFP ports are also known as mini-Gigabit interface converter (GBIC) modules, as they have replaced the older GBIC transceivers.
SFP Port Advantage
It is flexible for the SFP port link to the network. The SFP port is the I/O device which is able to be hot-plugged. We are able to insert the Gigabit Ethernet port or slot into the SFP port and then connect the SFP port with the network. The SFP port is applied in many products and is able to exchange with the port of the 1000BASE-SX, 1000BASE-LX/LH, 1000BASE-ZX or the 1000BASE- BX10-D/U.
Why Need SFP Module?
Compared with GBIC module, SFP Modules volume ratio reduced by half, and the number of ports can be configured more than 2 times on the same panel. That can be inserted mini head fiber module slot. The Other basic features are consistent with GBIC.SFP Modules for Gigabit Ethernet Applications: Small Form-Factor Pluggable (SFP) links your switches and routers to the network.
The hot-swappable input / output device plugs into a Gigabit Ethernet port or slot. Optical and copper models can be used on a wide variety of products and intermixed in combinations of 1000BASE-T, 1000BASE-SX, 1000BASE-LX / LH, 1000BASE-EX, 1000BASE-ZX, or 1000BASE-BX10-D / U on a port-by-port basis.
SFP Ports on a Gigabit Switch
SFP ports enable Gigabit switches to connect to a wide variety of fiber and Ethernet cables in order to extend switching functionality throughout the network.
The SFP devices allow the switch to connect to fiber cables of different types — including single-mode and multimode–and speeds (1 Gbps, 10 Gbps), or even Ethernet copper cables, such as CAT5e and CAT6.
Almost all enterprise-class switches include two or more SFP ports, allowing them to become part of a ring or star-based network topology spread among different buildings, floors or areas, and connected via fiber optic cabling.
The Hot SFP Modules
The latest SFP modules, such as GLC-BX-D and GLC-BX-U, support digital optical monitoring, which lets end users monitor the performance of SFPs in real time, tracking such metrics as temperature, optical output power, optical input power, transceiver supply voltage and laser bias current.
SFPs can support speeds of up to 1 Gbps, with transmission ranges of 10 kilometers (1000BASE-BX10-D), 40 km (GLC-BX40-D) or 80 km (GLC-BX80-D), depending on the model selected.
Newer SFP+ modules support increased speeds of up to 10 Gbps; however, not all rival SFP+ modules are automatically compatible.