What Is SFP?
SFP, short for small form-factor pluggable is a compact, hot-pluggable transceiver used for both telecommunication and data communications applications. SFP transceiver can be regarded as the upgrade version of GBIC module. Unlike GBIC with SC fiber optic interface, SFP is with LC interface and the main body size of SFP is only about half of GBIC so that it can save more space. SFP interfaces a network device mother board (for a router, switch, media converter or similar devices) to a fiber optic or copper networking cable. Meanwhile, SFP is a popular industry format supported by many network component vendors. It is designed to support SONET, Gigabit Ethernet, Fibre Channel, and other communications standards.

Standardization
The SFP transceiver is not standardized by any official standards body, but rather is specified by a Multi-source Agreement (MSA) among competing manufacturers. The SFP was designed after the GBIC interface, and allows greater port density (number of transceivers per cm along the edge of a mother board) than the GBIC, which is why SFP is also known as mini-GBIC. The related Small Form Factor transceiver is similar in size to the SFP, but is soldered to the host board as a through-hole device, rather than plugged into an edge-card socket.

However, as a practical matter, some networking equipment manufacturers engage in vendor lock-in practices whereby they deliberately break compatibility with "generic" SFPs by adding a check in the device's firmware that will enable only the vendor's own modules. For example, in 2003 during a routine Internet Operating System (IOS) update on their Catalyst line of switches, Cisco added a feature that would cause the switch to reject optical modules that were not deemed "Cisco brand".

Types of SFP Transceiver Modules
SFP Transceivers are available with a variety of transmitter and receiver types, allowing users to select the appropriate transceiver for each link to provide the required optical reach over the available optical fiber type (e.g. multi-mode fiber or single-mode fiber).

In the market, SFP transceiver modules are commonly available in several different categories:

For multi-mode fiber, with black or beige extraction lever
SX - 850 nm, for a maximum of 550 m at 1.25 Gbit/s (Gigabit Ethernet) or 150m at 4.25 Gbit/s (Fibre Channel)

For single-mode fiber, with blue extraction lever
LX - 1310 nm, for distances up to 10 km
EX - 1310 nm,for distances up to 40 km
ZX - 1550 nm, for distances up to 80 km
BX - 1490 nm 1310nm, for distances up to 10 km
1550 nm 40 km (XD), 80 km (ZX), 120 km (EX or EZX)

For copper twisted pair cabling
1000BASE-T - these modules incorporate significant interface circuitry and can only be used for Gigabit Ethernet, as that is the interface they implement. They are not compatible with (or rather: do not have equivalents for) Fibre channel or SONET.

For WDM (Wavelength Division Multiplex) system
BiDi SFP (Bidirectional SFP) for bi-directional traffic on a single fiber. Coupled with CWDM (Coarse Wavelength Division Multiplexing), these double the traffic density of fiber links
CWDM and DWDM (Dense Wavelength Division Multiplexing) transceivers at various wavelengths achieving various maximum distances

 Applications of SFP Transceiver Module
SFP is expected to perform at data speed of up to five gigabits per second (5Gbps), and possibly higher. Because SFP module can be easily interchanged, so electro-optical or fiber optic networks can be upgraded and maintained more conveniently than that with traditional soldered-in modules. Owing to its low cost, low profile and the ability to provide a connection to different types of optical fibers, SFP transceiver can result in a substantial cost savings, both in maintenance and in upgrading efforts. SFP transceiver is available with multi-mode single-mode fiber optics, allowing users to select the appropriate transceiver for each link in order to provide the required optical reach over the available optical fiber type. It is also available with copper cable interfaces, which allows a host device designed primarily for optical fiber communications to communicate over unshielded twisted pair networking cables. Modern optical SFP transceiver supports DDM (Digital Diagnostics Monitoring) functions, also known as DOM (Digital Optical Monitoring). This feature gives users the ability to monitor the real-time parameters of SFP transceiver, such as optical output power, optical input power, temperature, laser-bias current and transceiver supply voltage.

Click on Link to buy Compufox SFP Transceivers

Let’s take a closer look.

8 Degrees of Separation

The main difference between APC and UPC connectors is the fiber endface. APC connectors feature a fiber endface that is polished at an 8-degree angle, while UPC connectors are polished with no angle. UPC connectors are not exactly flat however; they have a slight curvature for better core alignment. Another more obvious difference is color. UPC adapters are blue while APC adapters are green.

What does the difference mean? With UPC connectors, any reflected light is reflected straight back towards the light source. The angled endface of the APC connector causes reflected light to reflect at an angle into the cladding versus straight back toward the source. This causes some differences in return loss, which is a measurement of reflected light that is expressed as a negative dB value (the higher the value, the better). Industry standards recommend that UPC connector return loss should be -50dB or greater, while APC connector return loss should be -60dB or greater.

Remember, return loss is different than insertion loss, which refers to the amount of optical power lost through a connector or cable length. Insertion loss is what we use to determine loss budgets. Achieving low insertion loss is typically easier with UPC connectors due to less air gaps than APC connectors. However, manufacturing techniques have improved significantly to create more precise angles on APC connectors and bring insertion loss down closer to that of UPC connectors. 

Application Considerations

There are some applications that are more sensitive to return loss than others that call for APC connectors. For example, in higher optical wavelength ranges (above 1500 nanometers) like those use for RF video signals, reflected light can adversely impact the signal. That is why we see APC connectors being used by most cable companies and other FTTX providers in outside plant applications.

APC connectors are also commonly used in passive optical applications (both GPONs and passive optical LANs) due to the fact that many of these systems also use RF signals to deliver video. Future higher-speed passive optical networks and other WDM applications that will use higher wavelengths via singlemode fiber will also likely require the reduced return loss of APC connectors.

One thing that should be noted is that APC and UPC connectors cannot and should not be mated. Not only does it cause poor performance since the fiber cores will not touch, but it can also destroy both connectors. The last thing you want to do is cause permanent transmitter damage—especially with higher-cost singlemode equipment.

This document describes how the Cisco^® 40-Gbps QSFP BiDi transceiver reduces overall costs and installation time for customers migrating data center aggregation links to 40-Gbps connections.

As a result of data center consolidation, server virtualization, and new applications that require higher data transport rates, the data center network is shifting to 10 Gbps at the access layer and 40 Gbps at the aggregation layer. A broad portfolio of high-performance and high-density 10- and 40-Gbps Cisco Nexus^® Family switches is available at attractive prices for this transition. However, to support 40-Gbps connectivity, data center architects are challenged by the need for a major upgrade of the cabling infrastructure, which can be too expensive or disruptive to allow data centers to quickly adopt and migrate to the 40-Gbps technology.

Cisco solves this problem with innovative 40-Gbps Quad Small Form-Factor Pluggable (QSFP) bidirectional (BiDi) technology that allows reuse of existing 10-Gbps fiber infrastructure for 40-Gbps connections.

Challenges with Existing 40-Gbps Transceivers

Standard short-reach (SR) 10- and 40-Gbps transceivers use fundamentally different connectivity formats, requiring fiber cabling infrastructure to be redesigned and replaced. 10-Gbps SR transceivers operate over dual-fiber multimode fiber (MMF) with LC connectors, and 40-Gbps SR protocols, such as SR4 and CSR4, operate over MMF ribbon with MPO connectors. As a result, 40-Gbps MPO-based SR4 transceivers cannot reuse aggregation fiber infrastructure built for 10-Gbps connectivity.

Connector type is not the only concern. Whereas 10-Gbps SR transceivers require 2 fiber strands per 10-Gbps link, 40-Gbps SR4 and CSR4 transceivers require a theoretical minimum of 8 fiber strands, and often 12 fiber strands in practice. The reason for this requirement is that 40-Gbps SR4 and CSR4 use 4 parallel fiber pairs (8 fiber strands) at 10-Gbps each for a total of 40-Gbps full duplex, as shown in Figure 1. However, both use MPO-12 connectors, which terminate 12-fiber ribbons. As a result, 4 fiber strands in each connection are unused and wasted.

To economize trunk fiber in a structured cabling environment, a 2 x 3 MPO fiber conversion module could combine three SR4 links onto two 12-fiber ribbon cables. But even then the 40-Gbps SR4 trunk still uses 8 fiber strands per link compared to 2 fiber strands in the case of 10-Gbps SR.

At best, the connector change and increased fiber density needed for SR4 require a significant cable plant upgrade, making it expensive and disruptive for customers to migrate from 10-Gbps connectivity to 40‑Gbps connectivity in their existing data centers.

Solution with Cisco 40-Gbps QSFP BiDi Transceiver

The Cisco QSFP BiDi transceiver, shown in Figure 2, transmits full-duplex 40-Gbps traffic over one dual-fiber LC-connector OM3 or OM4 MMF cable. It provides the capability to reuse 10-Gbps fiber infrastructure. In other words, it enables data center operators to upgrade to 40-Gbps connectivity without making any changes to the previous 10-Gbps fiber cable plant.

The Cisco QSFP BiDi transceiver has two 20-Gbps channels, each transmitted and received simultaneously over two wavelengths on a single MMF strand. The result is an aggregated duplex 40-Gbps link over a MMF duplex LC-terminated fiber cable. The connection can reach 100 meters on OM3 MMF or 150 meters on OM4 MMF, which is the same as 40-Gbps SR4. Figure 3 shows the technology concept of the Cisco QSFP BiDi transceiver.

Most Cisco switching and routing products that support 40 Gigabit Ethernet interfaces support the Cisco QSFP BiDi transceiver. For a complete list of supporting products, refer to the Cisco 40 Gigabit Optical Transceiver product page at http://www.cisco.com/en/US/products/ps11708/index.html.

Savings with Cisco QSFP BiDi When Migrating from 10 Gbps to 40 Gbps

This section presents two case studies that demonstrate the savings achieved by using Cisco QSFP BiDi technology for 40-Gbps connectivity in data center networks. The case studies show how Cisco QSFP BiDi technology can remove the cost barriers for migrating and expanding the existing 10-Gbps cabling footprint to 40-Gbps infrastructure to provide the higher data rate in the data center network.

Case Study 1: 288 x 40-Gbps Connections with Unstructured Cabling

In an unstructured cabling system, devices are connected directly with fiber cables. This direct-attachment design can be used to connect devices within short distances in a data center network. As shown in Figure 4, direct connection between two 40-Gbps devices can be provided by MMF cables with either QSFP SR4 or QSFP BiDi transceivers at two ends.

The QSFP SR4 transceiver uses MPO-12 connectors, whereas Cisco QSFP BiDi uses LC connectors. Existing 10-Gbps connections commonly are MMF cables with LC connectors. Therefore, with QSFP SR4 transceivers, none of the existing 10-Gbps MMF cables can be reused because the connector types are different. Cisco QSFP BiDi allows cable reuse, resulting in zero-cost cabling migration from direct 10-Gbps connections to direct 40-Gbps connections.

Table 1 summarizes the costs and savings of migration and new deployment of 288 direct connections. To migrate the existing 288 10-Gbps connections to 40-Gbps connections, Cisco QSFP BiDi does not require any new spending on cables. Therefore, in comparison to QSFP SR4 transceivers, Cisco QSFP BiDi transceivers reduce costs by 100 percent and provide savings of up to US$290 per 40-Gbps port.

Table 1.       Fiber Infrastructure Savings for 10-Gbps to 40-Gbps Direct-Cabling Migration and New 40-Gbps Deployment

For the case in which 288 new direct 40-Gbps connections are needed in addition to the existing cabling infrastructure for a data center migration or expansion, the savings for 288 new connections using Cisco QSFP BiDi instead of QSFP SR4 transceivers is as high as 77 percent and US$221 per 40-Gbps port. These numbers do not take into account the installation costs. Adding installation costs could easily double the SR4 deployment costs.

Case Study 2: 384 x 40-Gbps Connections with Structured Cabling

A structured cabling system is commonly deployed in data center networks to provide flexible and scalable cabling infrastructure. Structured cabling uses short patch cords to attach devices to a patch panel and then runs fiber trunks either to consolidate the cables in a central location for additional connectivity or to direct them to another patch panel to which the remote devices are attached. Figure 5 shows a simple example of a 10-Gbps structured cabling design.

For migration of a data center with a structured 10-Gbps cabling system, Cisco QSFP BiDi technology allows you to repurpose the existing cabling system - including the patch cables, patch panels with MTP/MPO LC modules, and fiber trunks - for 40-Gbps connectivity. In contrast, QSFP SR4 transceivers require new patch cables and patch panels because the connector types differ and the size of the fiber trunk needs to be quadrupled.

This case study examines a simple nonblocking two-tier fabric design (Figure 6) that provides 1536 10-Gbps edge ports on its leaf layer. Its spine layer is composed of two Cisco Nexus 9508 Switches, and its leaf layer consists of 32 Cisco Nexus 9396PX Switches, each with six 40-Gbps links to every spine Cisco Nexus 9508. There are 384 40-Gbps links total between the leaf and spine layers.

If 384 x 10-Gbps connections are to be reused to construct this network, no additional spending on cabling will be needed if Cisco QSFP BiDi transceivers are used for all the 40-Gbps links. This scenario thus offers a 100 percent cost savings compared to the cost of reconstructing the cabling system using QSFP SR4 transceivers, including the cost of new patch cables, new patch panels, and expansion of the current fiber trunk.

If the cabling for this network is a new (greenfield) deployment or an expansion of an existing cabling system, the 384 x 40-Gbps connections can be built by using MMF cables and either QSFP SR4 transceivers or Cisco QSFP BiDi transceivers. Figures 7 and 8 show design examples for each option. Table 2 compares real-world cost estimates for these two designs. The design with Cisco QSFP BiDi offers 77 percent savings over that with QSFP SR4 transceivers, which is equivalent to a savings of US$2077 per 40-Gbps connection.

Table 2.       Structured 40-Gbps Cable Infrastructure Cost Comparison

Conclusion

Cisco QSFP BiDi technology removes 40-Gbps cabling cost barriers for migration from 10-Gbps to 40-Gbps connectivity in data center networks. Cisco QSFP BiDi transceivers provide 40-Gbps connectivity with immense savings and simplicity compared to other 40-Gbps QSFP transceivers. The Cisco QSFP BiDi transceiver allows organizations to migrate the existing 10-Gbps cabling infrastructure to 40 Gbps at no cost and to expand the infrastructure with low capital investment. Together with Cisco Nexus 9000 Series Switches, which introduce attractive pricing for networking devices, Cisco QSFP BiDi technology provides a cost-effective solution for migration from 10-Gbps to 40-Gbps infrastructure.

Straight-Through Wired Cables

Straight-Through refers to cables that have the pin assignments on each end of the cable. In other words Pin 1 connector A goes to Pin 1 on connector B, Pin 2 to Pin 2 ect. Straight-Through wired cables are most commonly used to connect a host to client. When we talk about cat5e patch cables, the Straight-Through wired cat5e patch cable is used to connect computers, printers and other network client devices to the router switch or hub (the host device in this instance).

Crossover Wired Cables

Crossover wired cables (commonly called crossover cables) are very much like Straight-Through cables with the exception that TX and RX lines are crossed (they are at opposite positions on either end of the cable. Using the 568-B standard as an example below you will see that Pin 1 on connector A goes to Pin 3 on connector B. Pin 2 on connector A goes to Pin 6 on connector B etc. Crossover cables are most commonly used to connect two hosts directly. Examples would be connecting a computer directly to another computer, connecting a switch directly to another switch, or connecting a router to a router.Note: While in the past when connecting two host devices directly a crossover cable was required. Now days most devices have auto sensing technology that detects the cable and device and crosses pairs when needed.

Rollover Wired Cables

 Rollover wired cables most commonly called rollover cables, have opposite Pin assignments on each end of the cable or in other words it is "rolled over". Pin 1 of connector A would be connected to Pin 8 of connector B. Pin 2 of connector A would be connected to Pin 7 of connector B and so on. Rollover cables, sometimes referred to as Yost cables are most commonly used to connect to a devices console port to make programming changes to the device. Unlike crossover and straight-wired cables, rollover cables are not intended to carry data but instead create an interface with the device.

More than 100 companies suggest ways U.S. government can help advance the IoT

Many industry watchers feel the U.S. is slipping behind other countries, particularly Germany and China, in creating a unified national strategy for development of the Internet of Things or IoT. But federal leaders, in the early stages of involvement, reached out to the telecom industry for guidance.

Back in April the National Telecommunications and Information Administration, a part of the U.S. Department of Commerce, issued a “request for comments on the benefits, challenges and potential roles for the government in fostering the advancement of the Internet of Things.”

Two months later and the call for comment has been met in spades with more than 130 filings coming from a broad swath of telecom interests including carriers like AT&T, T-Mobile, Verizon and Vodafone; vendors including Nokia, Ericsson, Huawei and Samsung; and industry trade groups like the Wi-Fi Alliance, Wireless Infrastructure Association, the Open Connectivity Foundation and the GSMA.

Here’s a full list of the respondents and their filings with NTIA. A review of some of the filings indicates a strong industry expectation that the rapid uptake of IoT will require global coordination and will likely create new markets while disrupting existing ones.

Verizon representatives told NTIA: “To support this explosion of IoT devices, a robust and secure underlying communications network must serve as a foundation. That network requires both increased commercial spectrum and development of the underlying core infrastructure. We encourage all stakeholders to work together to ensure that these necessary building blocks for IoT development are available and accessible. To enable sufficient spectrum to power this new wave of connected innovation, private and public sectors must continue to cooperate, not only to develop more ways to effectively share spectrum, but also to provide federal users incentives to free up spectrum for commercial licensed and unlicensed use. As potentially billions of new IoT devices are deployed, they will drive data growth that – combined with the parallel growth in overall data usage by consumer devices – will require new commercial spectrum allocations to accommodate the unprecedented demands for more bandwidth. This includes spectrum necessary to support 5G, since 5G’s super-fast speeds and low latency will help facilitate new IoT use cases.”

Ericsson commented: “In Ericsson’s view, 5G is the technology that will unleash the true potential of the Internet of Things. To support the IoT’s development, the government should unleash the resources that will ensure U.S. leadership in 5G by releasing more spectrum for commercial use. Through network slicing, 5G technology will allow a single infrastructure to meet the very different needs of Massive and Critical IoT devices – it will enable networks to handle the incredible increase in data from the billions of low energy, low data devices, while also providing very high reliability, availability and security for critical uses. We also encourage the government to support global standards and best practices and to allow industry to continue to innovate and coalesce around the most favorable IoT solutions.”

And from the GSMA’s point of view: “The United States should forbear from regulating IoT and avoid reflexively extending legacy regulations designed for outdated technologies to the IoT…The U.S. government should support and promote industry alignment around interoperable, industry-led specifications and standards across the global IoT ecosystem…The U.S. government should promote the allocation of globally harmonized spectrum that can support IoT…The U.S. government should encourage industry to build trust into IoT devices. Existing laws and regulations, operating in tandem with self-regulatory regimes and best practices, will provide sufficient protection to consumers as the IoT develops…Finally, the U.S. government should engage on a bilateral and multilateral basis, as appropriate, to ensure that international IoT activities similarly encourage competition, investment, and innovation. Regulatory interference at this stage—from any source—could lead to fragmentation and impede innovation, inhibiting the IoT’s ability to reach its full potential to deliver benefits to consumers.”

AT&T expects to see opex savings from SDN and NFV in the range of 40% to 50% but it will take a few years to reach that goal, said Krish Prabhu, president of AT&T Labs, yesterday.  Prabhu discussed the prospects for software defined networking (SDN) and network functions virtualization (NFV) in a question and answer session at the Cowen and Company Annual Technology, Media & Telecom Conference, which was also webcast.

Opex savings from SDN and NFV will occur when network functions are controlled through software, replacing today’s approach that relies more heavily on manual operations, Prabhu said.

“Opex savings will materialize when [functions] are fully automated,” said Prabhu.

AT&T has established a goal of virtualizing 75% of its network by 2020 and by that point, the company expects to see margins increase – apparently because of opex savings – Prabhu noted.

Opex Savings from SDN and NFV Will Exceed Capex Savings
The results that AT&T expects from SDN and NFV on the capex side are not as ambitious as what the company forecasts for opex.

Krish Prabhu

Prabhu doesn’t expect to see any capex savings from SDN and NFV, but that statement only tells part of the story. AT&T is expecting to handle four to eight times more traffic on its network within a few years than it handles today – and the company expects to accommodate that growth without increasing capex as a result of implementing SDN and NFV, Prabhu said.

Prabhu’s comments are quite similar to those made by Verizon CFO Fran Shammo recently. Shammo told investors that Verizon’s  capex also would remain flat despite the implementation of SDN because of additional investment required to add small cells to the company’s wireless network.

AT&T also expects to invest substantially in small cells moving forward. Prabhu noted, for example, that while the company has built 90% of the macrocells it expects to need, it has only built 5% to 10% of the small cells it anticipates deploying.

DIRECTV Now
A key contributor to AT&T’s increasing bandwidth needs could be the company’s planned linear OTT video offering dubbed DIRECTV Now, which customers will be able to stream to a variety of wired and wireless devices.

According to Prabhu the company will be ready to meet bandwidth demand when the service launches later this year. On the wireless side, he noted that the company has 40 MHz of spectrum in the AWS-3 and WCS bands that will be available to support the new service.

 

The latest Ericsson Mobility Report forecasts such rapid growth in the number of global IoT devices that they will overtake mobile phones as the largest category of connected device by 2018. Ericsson reckons Western Europe will be the biggest growth driver for IoT devices, forecasting a 5x increase by 2021. This won’t necessarily be the result of a greater appetite for IoT by European consumers, however, with Ericsson saying directives such as eCall for cars and smart meters compelling the continent to increase its number of connected devices. “IoT is now accelerating as device costs fall and innovative applications emerge,” said Rima Qureshi, Chief Strategy Officer at Ericsson. “From 2020, commercial deployment of 5G networks will provide additional capabilities that are critical for IoT, such as network slicing and the capacity to connect exponentially more devices than is possible today.” While the majority of IoT devices will be connected via non-cellular means (presumably wired or wifi), cellular IoT devices are forecasts to be the fastest growing category. Ericsson reckons a major reason for that growth will be 3GPP standardization of cellular IoT technologies, by which it’s presumably referring to NB-IoT. Other notable findings from the latest report include the fact that global smartphone subscriptions are expected to overtake those of basic phones in Q3 of this year and that the use of cellular data for smartphone video has doubled among teens in the past year, in contrast to a significant fall in the amount of time they spend watching traditional TV. Additionally the first devices supporting 1 Gbps LTE download speeds are expected later this year. Lastly Ericsson used the report to bring attention to the need to harmonise 5G spectrum in the frequencies above those currently licensed for mobile but below the 24 GHz+ range that was addressed at WRC-15, including better accommodation for microwave backhaul. It said the 3.1-4.2 GHz range is considered essential for early deployments of 5G and offered the chart below to illustrate how un-harmonised the global microwave backhaul picture currently is.

Retro gaming giant Atari will soon be entering the IoT arena following a partnership with Sigfox, the low power WAN provider. Famed for its trailblazing old-school computers and gaming consoles in the 1980s and 1990s, an announcement from Atari said it will soon be developing and launching consumer IoT services. While tangible details weren’t particularly forthcoming, and won’t be for the time being, Atari did hint at a move back to hardware having been primarily, if not solely, focused on software and gaming for the best part of the last 20 years. Atari said the initial product line will include offerings in areas such as home, pets, lifestyle and safety. By combining with Sigfox, Atari plans on developing a wide range of new products, from the very simple to the highly sophisticated, which users can track at any time. Sigfox says that by connecting to its network, products will benefit from an extended battery life and no need for paring or connectivity configuration. “By partnering together and using SIGFOX’s dedicated IoT connectivity, we are going to create amazing products with our brand,” said Fred Chesnais, Chief Executive Officer, Atari. “We look forward to our collaboration with SIGFOX and releasing new products to the mass market on a global scale.” It’s fair to assume Atari is targeting a move back into hardware and away from gaming, although more information will be released in due course. Atari says development of the new product line will begin in 2016.

Qualcomm has announced new chips and technologies designed to boost domestic wifi coverage, at-home IoT connectivity, wearable tech capability and next generation broadband delivery.

Starting off with domestic wifi coverage boosting, and Qualcomm launched a new family of 802.11ac platforms designed to optimise device wifi usage by intelligently allocating radio spectrum in the home. It says its new three radio solutions combine two 5 GHz radios and a 2.4 GHz radio to help improve connectivity; and its platform, used on new routers and repeaters, can appropriately dedicate radio in the legacy 2.4 GHz band to devices only compatible with the 802.11n standard. This, in theory, can alleviate congestion on domestic networks and ensure more bandwidth availability for devices compatible with the newer 802.11.ac band.

Qualcomm says the self-organising features integrated into the new platform means it will become much easier to register and configure new devices on the network; while automatically allocating capacity for devices based on real-time conditions.

“As people rely on their home network to support more devices accessing the internet and streaming media, Wi-Fi is being stretched to the limit,” said Gopi Sirineni, vice president of product management, Qualcomm Atheros, Inc. “We are changing the game with features designed to deliver the best possible Wi-Fi experiences and now, uniquely, we are driving those technologies into more cost-effective products to extend the benefits to a wider swath of consumers.”

IoT is also in Qualcomm’s sights, as it unveiled a new chip set targeting low-power smart home devices. It says the QCA4012 chip brings dual band wifi, enhanced security, low power and small form factor for connected devices. Companion SDKs and services from partners Ayla, Exosite and Iota Labs include API interfaces and other tools to support IoT device and cloud integration.

“IOTA Labs has developed cutting edge IoT solutions integrating Qualcomm Technologies’ latest products with the IOTA Labs platform,” said Amit Singh, director and co-founder, IOTA Labs. “IOTA Labs’s leading edge IoT platform and experience acts as an accelerator for clients to transform their offerings into leading smarter products and services with a lower cost of ownership.”

The Snapdragon Wear 1100, included in the raft of announcements, joins the product line and targets consumer-led IoT products, including smart-accessories and wearable tech. Qualcomm says it has been designed to target  the wearable segment where a smaller size, longer battery life, smarter sensing, enhanced security. It also comes with a modem capable of LTE, wifi and Bluetooth support.

“We are delighted to add Snapdragon Wear 1100 to our Snapdragon Wear family, thus making it easier for customers to develop connected wearables with targeted use cases such as kid and elderly tracking,” said Anthony Murray, SVP of IoT for Qualcomm Technologies. “We are actively working with the broader ecosystem to accelerate wearables innovation and are excited to announce a series of customer collaborations today.”

Finally, Qualcomm also announced a fixed networking launch which it claims will help operators deliver up to 1 Gbps data rates on existing infrastructure up to 100 meters. The GigaDSL chipsets are intended to support gigabit data rates on existing telephone lines providing a high-speed extension for VDSL without losing spectrum capacity. It says existing infrastructure can be upgraded to the new processors without having to rip up the network and start again. The product line will become available from June for both fibre to the building and customer premises equipment.

“With these new GigaDSL product offerings, we are able to meet carriers’ broadband goals, complementing fiber deployment in time for major events, such as the 2018 Winter Games in Korea and the 2020 Summer Games in Japan,” said Irvind Ghai, VP of product management at Qualcomm Atheros.

Verizon and the Communications Workers of America (CWA) and International Brotherhood of Electrical Workers (IBEW) have come to a tentative agreement on a four-year labor contract, putting an end to a month long strike of the telco's nearly 40,000 wireline workers.

U.S. Secretary of Labor Thomas Perez announced the agreement in a statement issued on the agency's website Friday morning.

"Today, I am pleased to announce that the parties have reached an agreement in principle on a four-year contract, resolving the open issues in the ongoing labor dispute between Verizon's workers, unions, and management," Perez said in a statement. "The parties are now working to reduce the agreement to writing, after which the proposal will be submitted to CWA and IBEW union members for ratification."

Perez said that "I expect that workers will be back on the job next week."

Verizon offered the wireline unions a nearly 11 percent raise, a small increase in pension benefits, and a promise to add 1,400 new union jobs. In addition, Verizon agreed to scale back subcontracting and withdrew a proposal to relocate employees for extended periods -- two issues that were sticking points for the unions and the company. 

Marc Reed, Verizon's chief administrative officer, said in a statement that "Verizon is very pleased with this "agreement in principle." 

The tentative contract was praised by both leaders of the IBEW and CWA. Both unions said that they will share the contract details with their members for approval in the coming days.

"This tentative contract is an important step forward in helping to end this six-week strike and keeping good Verizon jobs in America," said Lonnie Stephenson, IBEW President, in a statement.

Chris Shelton, President of the CWA, echoed a similar sentiment.

"The agreement in principle at Verizon is a victory for working families across the country and an affirmation of the power of working people," Shelton said.

On May 16, Perez met with Lowell McAdam, chairman and CEO of Verizon; Chris Shelton, president of the Communications Workers of America; and Lonnie Stephenson, president of the International Brotherhood of Electrical Workers.

During that joint meeting, the three parties said they agreed to find a way to resolve their disputes and return to the bargaining table on Tuesday to continue talks.

After not being able to negotiate what the CWA and IBEW deemed a fair contract with Verizon, the company's wireline workers began their strike on April 13. 

At that time, neither the unions nor the company were able to come to an agreement over various issues related to health care, pension, and outsourcing job functions.

Huawei completes 5G key technology tests in 5G field trial

Strong Promotion for Global Partnership on 5G Technology Innovation and a Global 5G Standard

Launched by China Academy of Information and Communication Technology (CAICT), the IMT-2020 5G Promotion Group aims to foster a joint effort to promote 5G technology evaluation and field test among the global mobile industry and ecosystem to ensure the successful commercial deployment by 2020. One of the key objectives for IMT-2020 5G Promotion Group is to realize the 5G vision for the enhanced mobile broadband service as well as to create the new capabilities for 5G to enable the IoT and vertical services, this represents the unprecedented technical challenges such as to realize 10Gbps or peak rate 20Gbps user data rate, 100 billion connections, and 1 ms of end-to-end network latency for the 5G air interface.

Early this year, IMT-2020 5G Promotion Group announced a three phase 5G networks trial plan, spanning from 2016 to 2018, with a first phase test from September 2015 to September 2016. The first phase test is focused on key radio technologies and performance test.

As one of the core members in the IMT-2020 5G Promotion Group, Huawei actively contributed IMT-2020 5G Promotion Group and 5G technology test. In addition, Huawei established an extensive collaboration with CAICT, China Mobile, China Unicom, and China Telecom in the Chinese operator community to explore the innovative air-interface technologies to achieve best spectral efficiency and massive links capabilities. Huawei’s effort is focused on New Radio (NR) technology, which includes the optimized new air-interface, full-duplex and massive MIMO technologies, these are the enabling technologies to achieve the superior end-user experience for the emerging mobile broadband service such as 4K, 8K and virtual reality and augmented reality.

Best-in-Class Test Results Using 5G New Air Interface

The 5G air interface technology has been implemented through three novel foundational technologies, i.e., filtered Orthogonal Frequency Division Multiplexing (F-OFDM), Sparse Code Multiple Access (SCMA) and Polar code to meet 5G requirements and performance targets.

F-OFDM technology is the basis for creating ultra-flexible air-interface to adaptively fit all the 5G use-case scenarios defined by ITU-R with a single radio technology platform. It allows multiple concurrent radio numerologies and frame structure to deliver very diverse services; F-OFDM can ensure the future-proof for the 5G system to meet emerging innovative services requirements. The test results showed that F-OFDM can increase system throughput by 10% using those free guard bands in LTE system. In addition, F-OFDM supports asynchronous transmission from different users. Test results showed that it will provide 100% higher system throughput compared with that in LTE system in the presence of mixed service on the same carrier frequency with mixed radio numerologies. .

SCMA is to support massive connections and obtain higher system throughput simultaneously via the joint optimization on sparse SCMA codebook design and multi-dimensional modulation. It can further consider optimization on power allocation among different SCMA layers especially in downlink to improve total system throughput. The test results showed that SCMA is to increase the uplink connection number by 300% and at the same time increased the downlink system throughput up to 80%.

For Polar code, it allocates information to the highly reliable data locations in the code structure to transmit useful information of user and at the same time it supports channel coding of any code rate with an appropriate code construction to fit any future service requirements. The test results showed that Polar code provided coding gain from 0.5dB to 2.0dB compared with Turbo code used in LTE system.

System Integration of Innovative 5G Air Interface Technologies

The flexible system integration of several innovative 5G air-interface technologies, namely, F-OFDM, SCMA and massive MIMO has been verified in the first phase of key 5G technology tests. In the test, multi-user MIMO (MU-MIMO) supported up to 24 users and up to 24 parallel layers transmission on the same time-frequency resources. The test results showed that MU-MIMO can achieve 3.6Gbps cell average throughput using 100MHz system bandwidth, it is almost 10 times of that in LTE baseline system.

The trial has validated the optimal integration of the above new radio technologies and the capability of flexible 5G air-interface technologies, the trial is also served as a technical re-risk to support the on-going 3GPP standardization work.

Full Duplex Implemented in the First Phase of 5G Test

Full Duplex mode has also been tested in the first phase of 5G test. In the initial test stage on Full Duplex, it allows simultaneous transmitting and receiving of data at the base station with three level cascaded technologies, namely, passive analog cancellation, active analog cancellation, and digital cancellation. The test results showed that the Full Duplex can provide self-interference cancellation capability more than 113dB in real world environment and result in a total 90% system throughput gain over the conventional half duplex mode used today.

Huawei has successfully completed the first phase test of 5G technologies in China. "The trial of 5G technologies in China will be a great contribution to 5G applications in the future.” Dr. Wen Tong, Huawei 5G Chief Scientist emphasized that, "As a member of the IMT-2020 5G Promotion Group, Huawei is pleased to work with CAICT, China Mobile, China Unicom, and China Telecom, and took the initiative to be the first to complete 5G key technologies tests and corresponding system integration test based on our proposed 5G new air interface."

He also announced the plan of the second phase of 5G test which will focus mainly on the wide coverage, high hotspot capacity, and massive connections with high reliability, low latency with reduced power consumption.

Today we’re excited to announce the latest step in our global cloud infrastructure as Microsoft and Facebook announce plans to build “MAREA” – a new, state-of-the art subsea cable across the Atlantic. The new MAREA cable will help meet the growing customer demand for high speed, reliable connections for cloud and online services for Microsoft, Facebook and their customers. The parties have cleared conditions to go “Contract-In-Force” with their plans, and construction of the cable will commence in August 2016 with completion expected in October 2017.

We’re seeing an ever-increasing customer demand for high speed, reliable connections for Microsoft cloud services, including Bing, Office 365, Skype, Xbox Live, and Microsoft Azure. As the world continues to move towards a future based on cloud computing, Microsoft is committed to building out the unprecedented level of global infrastructure required to support ever faster and even more resilient connections to our cloud services. This robust, global infrastructure will enable customers to more quickly and reliably store, manage, transmit and access their data in the Microsoft Cloud.

“In order to better serve our customers and provide the type of reliable and low-latency connectivity they deserve, we are continuing to invest in new and innovative ways to continuously upgrade both the Microsoft Cloud and the global Internet infrastructure,” said Frank Rey, director, global network acquisition, Microsoft Corp. “This marks an important new step in building the next generation infrastructure of the Internet.”

MAREA will be the highest-capacity subsea cable to ever cross the Atlantic – featuring eight fiber pairs and an initial estimated design capacity of 160Tbps. The new 6,600 km submarine cable system, to be operated and managed by Telxius, will also be the first to connect the United States to southern Europe: from Virginia Beach, Virginia to Bilbao, Spain and then beyond to network hubs in Europe, Africa, the Middle East and Asia. This route is south of existing transatlantic cable systems that primarily land in the New York/New Jersey region. Being physically separate from these other cables helps ensure more resilient and reliable connections for our customers in the United States, Europe, and beyond.

Microsoft and Facebook designed MAREA to be interoperable with a variety of networking equipment. This new “open” design brings significant benefits for customers: lower costs and easier equipment upgrades which leads to faster growth in bandwidth rates since the system can evolve at the pace of optical technology innovation. This is critical to ensure the Microsoft Cloud continuously improves to provide the highest availability and performance our customers need for their mission-critical workloads and data.

Microsoft and Facebook are working with Telxius, Telefónica’s telecommunications infrastructure company, building upon their longstanding experience in subsea cables on this innovative new system. Telxius will serve as the operator of the system and sell capacity as part of their wholesale infrastructure business.

As one of the largest cloud operators in the world, Microsoft has invested more than $15 billion (USD) in building a resilient cloud infrastructure and cloud services that are highly available and highly secure while lowering overall costs. Microsoft has now announced 32 Azure regions around the world with 24 generally available today – more than any other major cloud provider. This latest investment, together with Microsoft’s previously announced investments in global fiber assets including the NCP trans-Pacific subsea cable, is further proof of Microsoft’s commitment to empower every person and every organization on the planet to achieve more.

Figure 1. Stack of Cisco Catalyst 3750 Series Switches with StackWise Technology

Figure 2. Stack of Cisco Catalyst 3750-E Series Switches with StackWise and StackWise Plus Technologies

Technology Overview

The Stack Interconnect Functionality

Bidirectional Flow

Online Stack Adds and Removals

Physical Sequential Linkage

Figure 3. Cisco StackWise Technology Resilient Cabling

Subsecond Failover

Figure 4. Loopback After Cable Break

Single Management IP Address

Stack Creation and Modification

1:N Master Redundancy

Master Switch Election

1. User priority - The network manager can select a switch to be master.

2. Hardware and software priority - This will default to the unit with the most extensive feature set. The Cisco Catalyst 3750 IP Services (IPS) image has the highest priority, followed by Cisco Catalyst 3750 switches with IP Base Software Image (IPB).

3. Default configuration - If a switch has preexisting configuration information, it will take precedence over switches that have not been configured.

4. Uptime - The switch that has been running the longest is selected.

5. MAC address - Each switch reports its MAC address to all its neighbors for comparison. The switch with the lowest MAC address is selected.

Master Switch Activities

Shared Network Topology Information

Subordinate Switch Activities

Multiple Mechanisms for High Availability

• CrossStack EtherChannel^® technology - Multiple switches in a stack can create an EtherChannel connection. Loss of an individual switch will not affect connectivity for the other switches.

• Equal cost routes - Switches can support dual homing to different routers for redundancy.

• 1:N master redundancy - Every switch in the stack can act as the master. If the current master fails, another master is elected from the stack.

• Stacking cable resiliency - When a break in the bidirectional loop occurs, the switches automatically begin sending information over the half of the loop that is still intact. If the entire 32 Gbps of bandwidth is being used, QoS mechanisms will control traffic flow to keep jitter and latency-sensitive traffic flowing while throttling lower priority traffic.

• Online insertion and removal - Switches can be added and deleted without affecting performance of the stack.

• Distributed Layer 2 forwarding - In the event of a master switch failure, individual switches will continue to forward information based on the tables they last received from the master.

• RPR+ for Layer 3 resiliency - Each switch is initialized for routing capability and is ready to be elected as master if the current master fails. Subordinate switches are not reset so that Layer 2 forwarding can continue uninterrupted. Layer 3 Nonstop Forwarding (NSF) is also supported when two or more nodes are present in a stack.

Layer 2 and Layer 3 Forwarding

Forwarding Resiliency During Master Change

High-Availability Architecture for Routing Resiliency Using Routing Processor Redundancy+

Adding New Members

Cisco IOS Software Images Must Be Identical

Automatic Cisco IOS Software Upgrade/Downgrade from the Master Switch

1. If the hardware of the new switch is supported by the Cisco IOS Software image running on the stack, the master will by default download the Cisco IOS Software image in the master's Flash memory to the new switch, send down the stack configuration, and bring the switch online.

2. If the hardware of the new switch is supported by the Cisco IOS Software image running on the stack and the user has configured a Trivial File Transfer Protocol (TFTP) server for Cisco IOS Software image downloads, then the master will automatically download the Cisco IOS Software image from the TFTP server to the new switch, configure it, then bring it online.

3. If the hardware of the new switch is not supported by the Cisco IOS Software image running on the stack, the master will put the new switch into a suspended state, notify the user of a version incompatibility, and wait until the user upgrades the master to a Cisco IOS Software image that supports both types of hardware. The master will then upgrade the rest of the stack to this version, including the new switch, and bring the stack online.

Upgrades Apply to All Devices in the Stack

Smart Unicast and Multicast - One Packet, Many Destinations

Figure 5. Comparison of Normal Multicast in Stackable Switches and Smart Multicast in Cisco Catalyst 3750 Series Switches Using Cisco StackWise Technology

QoS Mechanisms

QoS Applied at the Edge

Figure 6. QoS Model

Figure 7. Queuing

Jumbo Frame Support

Smart VLANs

Figure 8. Smart VLAN Operations

Cross-Stack EtherChannel Connections

StackWise Plus

1. For unicast packets, StackWise Plus supports destination striping, unlike StackWise support of source stripping. Figure 9 shows a packet is being sent from Switch 1 to Switch 2. StackWise uses source stripping and StackWise Plus uses destination stripping. Source stripping means that when a packet is sent on the ring, it is passed to the destination, which copies the packet, and then lets it pass all the way around the ring. Once the packet has traveled all the way around the ring and returns to the source, it is stripped off of the ring. This means bandwidth is used up all the way around the ring, even if the packet is destined for a directly attached neighbor. Destination stripping means that when the packet reaches its destination, it is removed from the ring and continues no further. This leaves the rest of the ring bandwidth free to be used. Thus, the throughput performance of the stack is multiplied to a minimum value of 64 Gbps bidirectionally. This ability to free up bandwidth is sometimes referred to as spatial reuse. Note: even in StackWise Plus broadcast and multicast packets must use source stripping, because the packet may have multiple targets on the stack.

Figure 9. Stripping

2. StackWise Plus can locally switch. StackWise cannot. Furthermore, in StackWise, since there is no local switching and since there is source stripping, even locally destined packets must traverse the entire stack ring. (See Figure 10.)

Figure 10. Switching

3. StackWise Plus will support up to 2 line rate 10 Gigabit Ethernet ports per Cisco Catalyst 3750-E.

Combining StackWise Plus and StackWise in a Single Stack

Management

Summary

Direct Attach Cable assemblies are a high speed, cost-effective alternative to fiber optic cables in 10Gb Ethernet, 8Gb Fibre Channel and InfiniBand applications. They are suitable for short distances, making them ideal for highly cost-effective networking connectivity within a rack and between adjacent racks. They enable hardware OEMs and data center operators to achieve high port density and configurability at a low cost and reduced power requirement.

Compufox SFP+ copper cable assemblies meet the industry MSA for signal integrity performance. The cables are hot-removable and hot-insertable: You can remove and replace them without powering off the switch or disrupting switch functions. A cable comprises a low-voltage cable assembly that connects directly into two SFP+ ports, one at each end of the cable. The cables use high-performance integrated duplex serial data links for bidirectional communication and are designed for data rates of up to 10 Gbps.

Types of SFP+ Direct Attach Copper Cables

Applications of SFP+ Direct Attach Copper Cables

Compufox SFP+ Direct Attach Copper Cables Solution

Compufox SFP+ twinax copper cables are avaliable with custom version and brand compatible version. All of them are 100% compatible with major brands like Cisco, HP, Juniper, Enterasys, Extreme, H3C and so on. If you want to order high quality compatible SFP+ cables and get worldwide delivery, we are your best choice.

For instance, our compatible Cisco SFP+ Copper Twinax direct-attach cables are suitable for very short distances and offer a cost-effective way to connect within racks and across adjacent racks. We can provide both passive Twinax cables in lengths of 1, 3 and 5 meters, and active Twinax cables in lengths of 7 and 10 meters. (Tips: The lengths can be customized up to the customers' requirements.)

FAQ of Compufox SFP+ Direct Attach Copper Cables

Q: What are the performance requirements for the cable assembly?
A: Our SFP+ copper passive and active cable assemblies meet the signal integrity requirements defined by the industry MSA SFF-8431. We can custom engineer cable assemblies to meet the requirements of a customer’s specific system architecture.

Q: Are passive or active cable assemblies required?
A: Passive cables have no signal amplification in the assembly and rely on host system Electronic Dispersion Compensation (EDC) for signal amplification/equalization. Active cable assemblies have signal amplification and equalization built into the assembly. Active cable assemblies are typically used in host systems that do not employ EDC. This solution can be a cost savings to the customer.

Q: What wire gauge is required?
A: We offer SFP+ cable assemblies in wire gauges to support customers' specific cable routing requirements. Smaller wire gauges results in reduced weight, improved airflow and a more flexible cable for ease of routing.

Q: What cable lengths are required?
A: Cable length and wire gauge are related to the performance characteristics of the cable assembly. Longer cable lengths require heavier wire gauge, while shorter cable lengths can utilize a smaller gauge cable.

For all you SFP+ Direct attach cables, please see link below. We carry compatible cables for most major brands.

http://www.compufox.com/SFP_Cables_s/337.htm

Fiber is the most expensive of the three and can run the longest distance. A number of types of connectors can work with fiber, but three you must know are SC, ST, and LC.

Twisted pair is commonly used in office settings to connect workstations to hubs or switches. It comes in two varicties: unshielded (UTP) and shielded (STP), The two types of connectors commonly used are RJ-11 (four wires and popular with telephones), and RJ-45 (eight wires and used with xBaseT networks—100BaseT, 1000BaseT, and so forth). Two common wiring standards are T568A and T568B.

Coaxial cabling is not as popular as it once was, but it's still used with cable television and some legacy networks. The two most regularly used connectors are F-conectors (television cabling) and BNC (10Base2, and so on).

Fiber

Fiber-optic cabling is the most expensive type. Although it's an excellent medium, it's often not used because of the cost of implementing it. It has a glass core within a rubber outer coating and uses beams of light rather than electrical signals to relay data. Because light doesn't diminish over distance the way electrical signals do, this cabling can run for distances measured in kilometers with transmission speeds from 100 Mbps up to 1 Gbps higher.

Often, fiber is used to connect runs to wiring closets where they break out into UTP or other cabling types, or as other types of backbones. Fiber-optic cable can use either ST, SC, or LC connector. ST is a barrel-shaped connector, whereas SC is squared and easier to connect in small spaces.The LC connector looks similar to SC but adds a flange on the top (much like an RJ-45 connector) to keep it securely connected.

Note: In addition to these listed in the A + objectives, other connectors are used with fiber. FC connectors may also be used but are not as common. MT-RJ is a popular connector for two fibers in a small form factor.

Twisted Pair

There are two primary types of twisted-pair cabling (with categories beneath cach that are shielded twisted pair (STP) and unshielded twisted pair (UTP). In both cases, the cabling is made up of pairs of wires twisted around each other.

UTP offers no shielding (hence the name) and is the network cabling type most prone to outside interference. The interference can be from a fluorescent light ballast, eletrical motor, or other such source (known as eletromagnetic interference [EMI]) or from wires being too close together and signals jumping across them (known as crosstalk), STP adds a foil shield around the twisted wires to protect against EMI.

STP cable uses IBM data connector (IDC) or universal data connector (UDC) ends and connects to token ring networks. While you need to know STP for the exam, you are not required to have any knowledge of the connectors associated with it. You must, however, know that most UTP cable uses RJ-45 connectors, which look like telephone connectors (RJ-11) but have eight wires instead of four.

Two wiring standards are commonly used with twisted-pair cabling:T568A and T568B (sometimes referred to simply as 568A and 568B). These are telecommunications standards from TIA and EIA that specify the pin arrangements for the RJ-45 connectors on UTP or STP cables. The number 568 refers to the order in which the wires within the Category 5 cable are terminated and attached to the connector. The signal is identical for both.

T568A was the first standard, released in 1991. Ten years later, in 2001, T568B was released. Pin numbers are read left to right, with the connector tab facing down. Notice that the pin-outs stay the same, and the only difference is in the color coding of the wiring.

Note: Mixing cables can cause communication problems on the network. Before installing a network or adding a new component to it, make sure the cable being used is in the correct wiring standard.

Coaxial

Coaxial cable, or coax, is one of the oldest media used in networks. Coax is built around a center conductor or core that is used to carry data from point to point. The center conductor has an insulator wrapped around it, a shield over the insulator, and a nonconductive sheath around the shielding. This construction allows the conducting core to be relatively free from outside interference. The shielding also prevents the conducting core from emanating signals externally from the cable.

Note: Before you read any further, accept the fact that the odds are incredibly slim that you will ever need to know about coax for a new installation in the real world (with the possible exception of RG-6, which is used from the wall to cable modem). If you do come across it, it will be in an existing installation and one of the first things you'll recommend is that it be changed. 

Classification of Techniques Used for Optical Fiber Splicing

This type of connection is made by fusing or melting the two ends together. This type of splice uses an electric arc to weld two fiber optic cables together and it requires specialised equipment to perform the splice. Fusion splices offer a lower level of loss and a high degree of permanence. However they require the use of the expensive fusion splicing equipment.

Mechanisms of Light Loss at Optical Fiber Joint

When joining optical fibers, the opposed cores must be properly aligned. Optical fiber splice loss occurs mostly in the following manner.

Poor concentricity

Poor concentricity of joined optical fibers causes a splice loss. In the case of general purpose single-mode fibers, the value of splice loss is calculated roughly as the square of the amount of misalignment multiplied by 0.2. (For example, if the light source wavelength is 1310 nm, misalignment by 1 µm results in approximately 0.2 dB of loss.)

Axial run-out

A splice loss occurs due to an axial run-out between the light axes of optical fibers to be joined. For example, it is necessary to avoid an increased angle at fiber cut end when using an optical fiber cleaver before fusion splicing, since such an angle can result in splicing of optical fibers with run-out.

Gap

An end gap between optical fibers causes a splice loss. For example, if optical fiber end faces are not correctly butt-joined in mechanical splicing, a splice loss.
 

Reflection

An end gap between optical fibers results in 0.6 dB of return loss at the maximum due to the change in refractive index from the optical fiber to the air. In addition, the whole optical fiber ends should be cleaned because loss can also occur due to dirt between optical fiber ends.

Classification and Principles of Fusion Splices

Fusion splicing is classified into the two methods, as follows:

Core alignment

Optical fiber cores observed with a microscope are positioned with the help of image processing so that they are concentrically aligned. Then, an electric arc is applied to the fiber cores. The fusion splicer used has cameras for observation and positioning in two directions.

Stationary V-groove alignment

This fusion splicing method uses V-grooves produced with high precision to position and orient optical fibers and utilizes the surface tension of melted optical fibers for alignment effects (cladding alignment). Splices made by this method achieve low loss thanks to the recent advancement of optical fiber production technology, which has improved the dimensional accuracy regarding the placement of core. This method is primarily used for splicing a multi-fiber cable in a single action.

 

Tips for Better Splices:

1. Thoroughly and frequently clean your splicing tools. When working with fiber, keep in mind that particles not visible to the naked eye could cause tremendous problems when working with fiber optics. "Excessive" cleaning of your fiber and tools will save you time and money down the road.

 

2. Properly maintain and operate your cleaver. The cleaver is your most valuable tool in fiber splicing. Within mechanical splicing you need the proper angle to insure proper end faces or too much light escaping into the air gaps between the two fibers will occur. The index matching gel will eliminate most of the light escape but cannot overcome a low quality cleave. You should expect to spend around $200 to $1,000 for a good quality cleaver suitable for mechanical splicing.

 

For Fusion splicing, you need an even more precise cleaver to achieve the exceptional low loss (0.05 dB and less). If you have a poor cleave the fiber ends might not melt together properly causing light loss and high reflection problems. Expect to pay $1,000 to $4,000 for a good cleaver to handle the precision required for fusion splicing. Maintaining your cleaver by following manufacturer instructions for cleaning as well as using the tool properly will provide you with a long lasting piece of equipment and ensuring the job is done right the first time.

 

3. Fusion parameters must be adjusted minimally and methodically (fusion splicing only). If you start changing the fusion parameters on the splicer as soon as there is a hint of a problem you might lose your desired setting. Dirty equipment should be your first check and them continue with the parameters. Fusion time and fusion current are the two key factors for splicing. Different variables of these two factors can produce the same splice results. High time and low current result in the same outcome as high current and low time. Make sure to change one variable at a time and keep checking until you have found the right fusion parameters for your fiber type.

OTDR (Optical Time Domain Reflectometer) is a familiar fiber test instrument for technicians or installers to characterize an optical fiber. To understand the specifications which may affect the performance of OTDR can help users get maximum performance from their OTDRs. This tutorial will introduce one of the key specifications—Dead Zone.

The OTDR dead zone refers to the distance (or time) where the OTDR cannot detect or precisely localize any event or artifact on the fiber link. It is always prominent at the very beginning of a trace or at any other high reflectance event.

OTDR dead zone is caused by a Fresnel reflection (mainly caused by air gap at OTDR connection) and the subsequent recovery time of the OTDR detector. When a strong reflection occurs, the power received by the photodiode can be more than 4,000 times higher than the backscattered power, which causes detector inside of OTDR to become saturated with reflected light. Thus, it needs time to recover from its saturated condition. During the recovering time, it can not detect the backscattered signal accurately which results in corresponding dead zone on OTDR trace. This is like when your eyes need to recover from looking at the bright sun or the flash of a camera. In general, the higher the reflectance, the longer the dead zone is. Additionally, dead zone is also influenced by the pulse width. A longer pulse width can increase the dynamic range which results in a longer dead zone.

In general, dead zones on an OTDR trace can be divided into event dead zone and attenuation dead zone.

The event dead zone is the minimum distance between the beginning of one reflective event and the point where a consecutive reflective event can be detected. According to the Telcordia definition, event dead zone is the location where the falling edge of the first reflection is 1.5 dB down from the top of the first reflection.

The attenuation dead zone is the minimum distance after which a consecutive non-reflective event can be detected and measured. According to the Telcordia definition, it is the location where the signal is within 0.5 dB above or below the backscatter line that follows the first pulse. Thus, the attenuation dead zone specification is always larger than the event dead zone specification.

Note: In general, to avoid problems caused by the dead zone, a launch cable of sufficient length is always used when testing cables which allows the OTDR trace to settle down after the test pulse is sent into the fiber so that users can analyze the beginning of the cable they are testing.

There is always at least one dead zone in every fiber—where it is connected to the OTDR. The existence of dead zones is an important drawback for OTDR, specially in short-haul applications with a large number of fiber optic components. Thus, it is important to minimize the effects of dead zones wherever possible.

As mentioned above, dead zones can be reduced by using a lower pulse width, but it will decrease the dynamic range. Thus, it is important to select the right pulse width for the link under test when characterizing a network or a fiber. In general, short pulse width, short dead zone and low power are used for premises fiber testing and troubleshooting to test short links where events are closely spaced, while a long pulse width, long dead zone and high power are used for long-haul fiber testing and communication to reach further distances for longer networks or high-loss networks.

The shortest-possible event dead zone allows the OTDR to detect closely spaced events in the link. For instance, testing fibers in premises networks (particularly in data centers) requires an OTDR with short event dead zones since the patch cords of the fiber link are often very short. If the dead zones are too long, some connectors may be missed and will not be identified by the technicians, which makes it harder to locate a potential problem.

Short attenuation dead zones enable the OTDR not only to detect a consecutive event but also to return the loss of closely spaced events. For instance, the loss of a short patch cord within a network can now be known, which helps technicians to have a clear picture of what is actually inside the link.

OTDR is one of the most versatile and widely used fiber optic test equipment which offers users a quick, accurate way to measure insertion loss and shows the overview of the whole system you test. Dead zone, with two general types, is an important specification of OTDR. It is necessary for users to understand dead zone and select the right configuration in order to get maximum OTDR performance during test. In addition, OTDRs of different brands are designed with different minimum dead zone parameters since manufacturers use different testing conditions to measure the dead zones. Users should choose the suitable one according to the requirements and pay particular attention to the pulse width and the reflection value.

What is Fiber Media Converter?

Fiber media converter is a transfer media that connects two dissimilar media types. Generally, it is a device that converts electrical signal used in copper unshielded twisted paired (UTP) network cabling into light waves used in fiber optic cabling, and vice versa. This kind of fiber media converter is called copper-to-fiber media converter that provides a simple way to introduce fiber into a LAN without tearing out the existing copper wiring or making changes to copper-based switches. Furthermore, there is another kind of fiber media converter that supports fiber-to-fiber conversion, which provides connections between dual-fiber and single-fiber or between multimode fiber and single-mode fiber. Fiber-to-fiber media converters also provide a cost-effective solution for wavelength conversion in Wavelength Division Multiplexing (WDM) applications, which are also known as transponders.

Types of Fiber Media Converters

There are a wide variety of fiber media converters available in the market. According to different criteria, fiber media converters may be classified into different types.

Managed VS Unmanaged

The managed fiber media converter has the functions of networking monitoring, fault detection and remote management. It helps the network administrator to easily monitor and manage the network. An unmanaged fiber media converter, however, allows for simple communication with other devices and does not have the monitoring and management functions that managed fiber media converter has.

Platform: Stand-Alone VS Modular Chassis-Based

According to the platform type, fiber media converters can be divided into stand-alone fiber media converter and modular chassis-based fiber media converter. Stand-alone fiber media converters are designed to be used in where a single or limited number of converter(s) need(s) to be quickly implemented. Modular chassis-based fiber media converters, however, are used in high-density applications that multiple points of copper and/or fiber integration are essential.

Copper-to-Fiber Media Converter VS Fiber-to-Fiber Media Converter

According to media types, fiber media converters may be classified into copper-to-fiber media converter and fiber-to-fiber media converter.

Copper-to-Fiber Media Converter

Copper-to-fiber media converters are the key to integrating fiber into a copper infrastructure. According to different applications, copper-to-fiber media converters may be further divided into Ethernet copper-to-fiber media converters, video-to-fiber media converters and serial-to-fiber media converters.

Ethernet Copper-to-Fiber Media Converter

This kind of fiber media converter supports the IEEE 802.3 standard and provides connectivity for Ethernet, fast Ethernet, Gigabit and 10 Gigabit Ethernet devices. SC to RJ45 media converters, SFP to RJ45 media converters, PoE media converters, mini media converters and industrial media converters are all among this type.

Video Copper-to-Fiber Media Converter

Video copper-to-fiber media converter also called fiber optic multiplexer, which is used to transmit and receive signals such as video, audio, data and Ethernet. fiber optic multiplexers are devices that process two or more light signals through a single optical fiber (as shown in the following figure), increasing the amount of information that can be carried through a network. Since signals may be analog or digital, video copper-to-fiber can be further divided into converters transmitting analog signals and converters transmitting digital signals. As the name applies, converters transmitting analog signals give amplitude or frequency modulation of the electric signal and then convert it into optical signal. Demodulation will also be done at the receiving end. Converters transmitting digital signals, however, digitize and multiplex the video, audio and data signals, transforming multiple low-speed digital signals into one high-speed signal. This high speed signal will then be turned into optical signal transmitting on a fiber.

In accordance with different applications, there are three commonly used video copper-to-fiber media converters: plesiochronous digital hierarchy (PDH) multiplexers, synchronous digital hierarchy (SDH) multiplexers and synchronous plesiochronous sigital hierarchy (SPDH) multiplexers. Using the PDH fiber transmission technologies, PDH multiplexers are E1 point-to-point optical transport equipment. And the general transmission capacity of this kind of multiplexer is 4E1，8E1 and 16E1. SDH multiplexers, having a large transmission capacity, are designed to support end-to-end provisioning and management of services across all segments of the optical network. SPDH multiplexers adopt both PDH and SDH technologies. It is a PDH transmission system that based on the PDH code speed adjustment principle at the same time, use as far as possible parts of the SDH network technology.

Serial-to-Fiber Media Converter

This kind of media converter provides fiber extension for serial protocol copper connections. It accepts serial data on one port in RS232, RS485 or other format and convert the serial data stream into a fiber optic signal to a matching unit at the other end of the fiber span.

Fiber-to-Fiber Media Converter

Fiber-to-fiber media converters are used to extend network distance by providing connectivity between multimode and single-mode fiber, between different “power” fiber sources and between dual fiber and single-fiber. Furthermore, they also support conversion from one wavelength to another. Mode converter and WDM OEO transponder are two common types of fiber-to-fiber media converters.

Mode Converter

A mode converter can be used to allow for an adiabatic transition between two optical modes. Other than cross-connecting different fiber types, mode converters can also re-generate optical signals, extending transmission distance and double fiber cable usage. It is usually applied in multi-mode to single-mode fiber conversion.

WDM OEO Transponder

When a fiber media converter is used in the WDM system, it is called WDM OEO transponder which converts the incoming signal from the end or client device to a WDM wavelength. WDM OEO transponders are often used for dual fiber to single fiber conversion and wavelength conversion.

Networks may require conversion between dual and single-fiber, depending in the type of equipment and the fiber installed in the facility. The following figures shows the role of WDM transponder played in the fiber optic network.

WDM OEO transponders are capable of wavelength conversion by using small form-factor pluggable (SFP) transceivers that transmit different wavelengths, provide a cost-effective solution to convert from standard optical wavelengths (850nm, 1310nm and 1550nm) of legacy equipment to optical wavelengths specified for WDM networks.

Selection Guide of Fiber Media Converters

A proper fiber media converter may provide a cost-effective solution for extending Ethernet transmission while reducing cable and labor cost. When selecting fiber media converters for your network, the following points should be taken into consideration: