The Basics of Optical Switch

Optical networking technology has grown rapidly and helped solve the problem of increasing demand for higher transfer data rates and bandwidths. In optical networks, optical fiber is the fundamental medium of transmission, but functions like switching, signaling and processing are accomplished electronically. To achieve conversions between optical signals and electrical signals, optical switches are naturally developed. What is an optical switch? This post will offer some basic information about optical switches.

Introduction

In telecommunication, an optical switch is a switch that enables signals in optical fibers or integrated optical circuits (IOCs) to be selectively switched from one circuit to another. An optical switch may operate by mechanical means, such as physically shifting an optical fiber to drive one or more alternative fibers, or by electro-optic effects, magneto-optic effects, or other methods.

Types of Optical Switches

An optical switch is simply a switch which accepts a photonic signal at one of its ports and send it out through another port based on the routing decision made. There are two kinds of optical switches, which are O-E-O (optical-electrical-optical) optical switch and O-O-O (optical-optical-optical) optical switch, also known as all optical switch. OEO switch requires the analogue light signal first to be converted to a digital form, then to be processed and routed before being converted back to an analogue light signal. OOO switching is done purely through photonic means.

Applications of Optical Switches

Optical switches are widely used in high speed networks where high switching speeds and large switches are required to handle the large amount of traffic. Optical switches are likely used within optical cross-connects (OXCs). An OXC may contain a whole series of optical switches. OXCs are similar to electronic routers which forward data using switches. Optical switches can also be used for switching protection. If a fiber fails, the switch allows the signal to be rerouted to another fiber before the problem occurs. It takes an optical switch milliseconds to detect the failure and inform network and switch. Besides, optical switches can be utilized for external modulators, OADM (optical add-drop multiplexers), network monitors and fiber optic component testing. In early days, original optical transceivers were required to be plugged into these switches. Now third-party optical transceivers are produced to save the cost. As shown below, you can test the compatibility of a fiber optic transceiver, such as Avago AFBR-79EIPZ compatible QSFP+ transceiver, HP JD089B compatible 1000BASE-T SFP transceiver or HP J4859C compatible 1000BASE-LX SFP transceiver in an optical switch.

Advantages of Optical Switches

Optical switches have several advantages compared with electric switches. They can save room and power consumption significantly, about up to 92 percent space and 96 percent power. If power savings are translated into cost savings, it means 3 kw can be reduced for each rack, which can save carriers from expensive diesel power generators, rectifiers and batteries, and save monthly maintenance costs for these devices and the purchasing and maintenance of cooling equipment for these devices. Optical switches are more scalable and faster than electric switches. All-optical switches are protocol and bit rate independent, so transfer rates will not be affected by bit rate limitations of switching equipment.

Disadvantages of Optical Switches

Optical switches also have some disadvantages. Currently, optical switches can not realize the technology to store photonic signals as easily as electrical signals. But they can store signals using fiber delay lines, as light takes a certain time to travel through a certain length of fiber (200,000 km per second in silica), which means a 10000 bit frame traveling at 10Gb/s requires 200m fiber. That is both expensive and impractical. And once a signal is put through a delay line, it cannot be processed until it comes back out. A solution to this is adding switches within the lines, but that will increase the costs. Optical switches cannot process header information of packets, especially at high traveling speed. The maximum speed electronic routers currently can operate is 10Gb/s while optical signals can travel up to 40/100Gb/s or even higher. Thus, the routers will not be able to process the signals as fast as the transmission.

Conclusion

With the increasing demand for video and audio and challenges of data capabilities and high bandwidth of networks, optical networks have gradually become the most cost-effective solution. Optical switches can provide customers with significant power, space and cost savings. Today, the optical switch market is dominated by several companies, such as Cisco, HP, Arista, and Juniper. You can choose an optical switch based on your needs.

Comparison Between Twisted Pair Cable, Coaxial Cable and Fiber Optic Cable

A communication system usually uses a wire or cable to connect transmitting and receiving devices. Currently, there are mainly three cable types deployed in communication systems, which are twisted pair cables, coaxial cables and fiber optic cables. Each type has been widely utilized in communication networks. What’s the difference between these three kinds of cables? This article will make a comparison between them.

Twisted Pair Cables

Twisted pair cable consists of a pair of insulated wires twisted together, which has been adapted in the field of telecommunication for a long time. With the cable twisting together, it helps to reduce noise from outside sources and crosstalk on multi-pair cables. Basically, twisted pair cable can be divided into two types: unshielded twisted-pair (UTP) cable and shielded twisted-pair (STP) cable. UTP cable, such as data communication cables and normal telephone cables, serves as the most commonly used cable type with merely two insulated wires twisted together. STP cable distinguishes itself from UTP cable in that it includes a foil jacket which helps to prevent crosstalk and noise from outside source. STP cable is typically used to eliminate inductive and capacitive coupling, and it can be applied between equipment, racks and buildings. The table below shows several different types of twisted pair cables.

Coaxial Cables

Coaxial cable is a type of high-frequency transmission cable which contains a single solid-copper core. A coaxial cable has over 80 times the transmission capability of the twisted-pair cable. Coaxial cables are commonly used to deliver television signals and to connect computers in a network as well. There are mainly two kinds of coaxial cables: 75 Ohm coaxial cable and 50 Ohm coaxial cable.

75 Ohm coaxial cable

The primary use of 75 Ohm coaxial cables is to transmit video signals. One typical application of 75 Ohm coaxial cable is to transmit television signals over cable, which is why sometimes it is called signal feed cables. The most common connector type used in this application is a Type F. Another application is video signals between components, such as DVD players, VCRs or receivers commonly known as audio/video (A/V) cables. In this case, BNC and RCA connectors are often found. In both applications, RG59 with both solid center conductor (RG59B/U) and stranded center conductor (RG59A/U) as well as RG6 are common choices.

50 Ohm coaxial cable

The primary use of 50 Ohm coaxial cables is the transmission of data signals in a two-way communication system. Several common applications for 50 Ohm coaxial cables are computer ethernet backbones, wireless antenna feed cables, GPS (Global Positioning Satellite) antenna feed cables and cell phone systems.

Fiber Optic Cables

Computing and data communications are fast-developing technologies. To meet the transmission of ever-increasing data rates, there comes a new generation of transmission medium, which is fiber optic cable. Fiber optic cable transmits information using beams of light at light speed rather than pulses of electricity. It refers to the complete assembly of optical fiber. A fiber optic cable can contain one or more strands of optical fiber to transmit data. Each strand of optical fiber is individually coated by plastic layers and contained in a protective tube. Fiber optic cable transmits data as pulses of light go through tiny tubes of glass, the transmission capacity of which is 26,000 times higher than that of twisted-pair cable. When comparing with coaxial cables, fiber optic cables are lighter and more reliable for transmitting data.

Two widely used types of fiber optic cables are single-mode fiber optic cables and multimode fiber optic cables. A single-mode optical fiber has a small core, and only allows one mode of light to propagate at a time. It is generally adapted to high speed and long-distance applications. A multimode optical fiber has a larger core diameter than a single-mode optical fiber and it is designed to carry multiple light rays, or modes at the same time. It is mostly used for communication over short distances because of its high capacity and reliability, serving as a backbone applications in buildings. And there are many connector types for fiber optic cable, such as LC, SC, ST or FC connector. You can choose fiber optic cables terminated at both ends with the same or different connector types to connect different devices, like LC SC fiber patch cable, LC to LC fiber patch cable. There are both single-mode and multimode, and simplx and duplex fiber optic patch cables for your options, such as LC to LC multimode duplex fiber optic patch cable, LC to SC duplex single-mode fiber optic patch cable, or LC LC multimode fiber patch cord.

Conclusion

As the technology in the field of network is developing rapidly, fiber optic cables seem to become the trend to meet the increasing demand of data rates in the market. However, whether to choose twisted pair cables, coaxial cables or fiber optic cables still depends heavily on applications. And other factors, such as the cost, transmission distance and performance, also need to be taken into consideration when making a choice.

Benefits of 10GBASE-T in 10GbE Data Center Migration

Large enterprises have been migrating their data center infrastructures accordingly with the bandwidth migrating from 100M Ethernet to 1/10 Gigabit Ethernet (GbE). 10GbE in the data center is very common now for 10GbE technology has been very mature. There are many interfaces options for 10GbE, such as CX4, SFP+ fiber, 10GBASE-T, and SFP+ direct attach copper (like HP J9281B SFP+ passive direct attach copper cable, or HP JG081C SFP+ passive direct attach copper cable). Among them, which one will you choose? Each one has its own advantages and disadvantages. In this post, we will talk about benefits of 10GBASE-T in 10GbE data center migration.

Shortcomings of SFP+ in 10GbE Data Center Migration

SFP+ has been adopted on Ethernet adapters and switches and supports both copper and fiber optic cables, which makes it a better solution than CX4. However, SFP+ optical transceiver (such as Cisco SFP-10G-LR-S 10GBASE-LR SFP+ transceiver) is not backward-compatible with the twisted-pair 1GbE broadly deployed throughout the data center. SFP+ connectors and their cabling were not compatible with the RJ-45 connectors used on 1GbE networks. Enterprise customers cannot just start adding SFP+ 10GbE to an existing RJ-45 1GbE infrastructure. New switches and new cables are required, which is a big chunk of change.

Why Choose 10GBASE-T in 10GbE Data Center Migration?

10GBASE-T is backward-compatible with 1000BASE-T, it can be deployed in the existing 1GbE switch infrastructures in the data centers that are cabled with CAT6, CAT6A or above cabling. As we know, 1GbE is still widely used in data center. Thus, 10GBASE-T is a great choice for gradual transition from 1GbE deployment to 10GbE. Other advantages of 10GBASE-T include:

Reach

Like all BASE-T implementations, 10GBASE-T works for lengths up to 100 meters, which gives IT managers a far-great level of flexibility in connecting devices in the data center. 10GBASE-T can accommodate either top of the rack, middle or end of the row network topologies, giving IT managers flexibility in server placement since it will work with the existing structured cabling systems.

Power

The challenge with 10GBASE-T is that even single-chip 10GBASE-T adapters consume a watt or two more than the SFP+ alternatives. More power consumption is not a good thing in the data center. However, the expected incremental costs in power over the life of a typical data center are far less than the amount of money saved from reduced cabling costs. Besides, with process improvements, chips improved from one generation to the next. The power and cost of the latest 10GBASE-T PHYs will be reduced greatly than before.

Reliability

Another challenge with 10GBASE-T is whether it could deliver the reliability and low bit-error rate of SFP+, or whether the high demands of FCoE could be met with 10GBASE-T. Cisco has announced that it had successfully qualified FCoE over 10GBASE-T and is supporting it on its newer switches that support 10GBASE-T in 2013.

Latency

10GBASE-T has a low latency range, from just over 2 microseconds to less than 4 microseconds. Latency for 10GBASE-T is more than 3 times lower than 1000BASE-T at larger packet sizes. Only the most latent sensitive applications such as HPC or high frequency trading systems would notice any latency.

Cost

When it comes to the cost, copper cables offer great savings. Typically, passive copper cables are two to five times less expensive than comparable lengths of fiber optic cables. In a 1,000-node cluster, with hundreds of required cables, that can translate into hundreds of thousands of dollars. Extending that into larger data centers, the savings can reach millions. Besides, copper cables do not consume power and because their thermal design requires less cooling, there are extensive savings on operating expenditures within the data center.

Conclusion

10GbE technology is very mature, reliable and well understood now. 10GBASE-T breaks through cable installation barriers in 10GbE deployment as well as offering investment protection via backwards compatibility with 1GbE networks. 10GBASE-T can save you money. By providing an easier path to migrate to 10GbE infrastructure, deployment of 10GBASE-T will simplify the networking transition in support of higher bandwidth needed for virtualized servers.

What Is LSZH Fiber Optic Cable?

When choosing fiber optic jumper cables, other than selecting the right connector type on both ends of the cable, such as SC to LC fiber cable, ST ST fiber patch cable, SC/APC to LC patch cable, SC to ST fiber cable, LC to ST fiber patch cable, or SC to SC patch cord, you also need to pay much attention to the construction of fiber optic cables. Nowadays, with increasing amount of cables found in residential, commercial and industrial applications, there is a greater fuel load in the event of a fire. Wire and cable manufacturers responded by developing materials that had a high resistance to fire while maintaining performance. Low-smoke, zero-halogen (LSZH) cables proved to be a key materials group that delivered enhanced fire protection performance. How much do you know about LSZH cables? This post aims at helping you learn more about LSZH fiber optic cables.

Introduction

LSZH stands for low-smoke zero-halogen, and describes a cable jacket material that is non-halogenated and flame retardant. This type of jacket material has excellent fire safety characteristics of low smoke, low toxicity and low corrosion. When LSZH fiber optic cables (as shown below) come in contact with a flame, very little smoke is produced, making them ideal for applications where a lot of people are confined in a certain place, such as office buildings, train stations, airports, etc. A fire may be very harmful in a building, and at the same time, the smoke can cause even more damage to people who are trying to locate exits and inhalation of smoke or gases. LSZH fiber optic cables are free of halogenated materials like Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I) or Astatine (At), and those materials are reported to be capable of being transformed into toxic and corrosive matter during combustion. Low-smoke property of LSZH fiber optic cables makes them safe and helpful. More people in fires die from smoke inhalation. LSZH fiber optic cables release low smoke and zero halogenated materials in these places would be really important to the safty of people.

Applications of LSZH Fiber Optic Cables

There is no doubt that the amount of fiber optic cables installed in buildings has been increasing as data communication proliferates. LSZH fiber optic cables have been common in central office telecommunication facilities, due to the large relative fuel load represented by wire and cable. Several applications of LSZH fiber optic cables are:

• Public spaces like train stations, hospitals, schools, high buidings and commercial centers where the pretection of people and equipment from toxic and corrosive gases is critical.
• Data centers contain large amounts of cables, and are usually enclosed spaces with cooling systems that can potentially disperse combustion byproducts through a large area. Other materials burning may also contribute greater amounts of dangerous gases which will outweigh the effect of the cables. There have been notable fires where cables burning contributed to corrosion, but in some instances, better fire response techniques could have prevented this damage.
• Nuclear industry is another area where LSZH fiber optic cables have been and will be used in the future. Major cable manufacturers have been producing LSZH fiber optic cables for nuclear facilities since the early 1990s. The expected construction of new nuclear plants in the U.S. in coming years will almost certainly involve LSZH fiber optic cables.

Tips for Choosing LSZH Fiber Optic Cables

No two products are the same and many factors will define the suitability of the final product to its application. Research shows that 27 LSZH compounds have huge variation in physical properties. Even using material which meets the base requirements of one of the many specifications available may not result in the best material for the application. When choosing LSZH fiber optic cables, factors such as the environment and price should be considered. An environmental factor such as the temperature of the installation could reduce the flexibility of the cable. Will the application be in an open area or confined? Will other flammable material be present? Many factors need to be taken into consideration. LSZH fiber optic cables also tend to be higher in cost.

Conclusion

When selecting or designing a fiber optic cable or fiber optic jumper cable for any application, the operating enviroments where the fiber optic cable will be used, whether extreme or not, must be considered along with availability, performance, and price. And when the safety of humans and the enviroment is a consideration, along with high-performance and capability, LSZH fiber optic cables provide a good solution for you.

Introduction to Fiber Breakout Cable

When talking about direct attach cables, we may come across breakout cable, such as Cisco QSFP+ breakout cable. There are many kinds of breakout cables, and they are suitable for various applications. For example, a Cisco QSFP-4SFP10G-CU5M compatible QSFP+ to 4 SFP+ passive direct attach copper breakout cable, as shown below, connects to a 40G QSFP+ port of a Cisco switch on one end and to four 10G SFP+ ports of a Cisco switch on the other end, and is used for very short distances and offers a very cost-effective way to connect within racks and across adjacent racks. Other than copper breakout cable, there is also fiber breakout cable. What is fiber breakout cable? How much do you know about fiber breakout cable? In this post, a brief introduction to fiber breakout cable will be given.

What Is Fiber Breakout Cable?

Breakout-style fiber optic cable, also called fiber breakout cable or fiber fan-out cable, is an optical cable which contains several jacketed simplex optical fibers package together inside an outer jacket. It differs from a distribution-style cable, in which tight-buffered fibers are bundled together, with only the outer cable jacket of the cable protecting them. The design of breakout-style cable adds strength for ruggedized drops, however the cable is larger and more expensive than distribution-style cable. The structure of fiber breakout cable (shown as the figure below) ensures a long life. A fiber breakout cable consists of outer jacket, tap binder, breakout fiber assembly (tight-buffered fiber surrounded in aramid yarns and jacketed), strength member, and ripcord. For easier handling, it also features an easily strippable 900µm coating. Both the PVC and plenum cables are rated for fire safety.

Features of Fiber Breakout Cable

• The key purpose of fiber breakout cable is that one can “break out” several fibers at any location, routing other fibers elsewhere.
• Each numbered fiber sub unit is protected by a layer of aramid yarn and encased in a FRNC/LSNH jacket. The individual sub units are cabled and then jacketed with a flame resistant FRNC/LSNH compound. Each fiber uses either the tight buffer technology or semi-tight buffer technology for excellent fiber stripping.
• Each fiber of a breakout cable has its own jacket and aramid strength elements, so each fiber is extremely strong and rugged.
• Fiber breakout cable is available in a variety of designs that will accommodate the topology requirements found in rugged environments. Fiber counts from simplex to 256 are available.
• A tight buffer design is used along with individual strength members for each fiber. This permits direct fiber cable termination without using breakout kits or splice panels.
• Due to the increased strength of Kevlar members, fiber breakout cables are heavier and larger than the telecom types with equal fiber counts.
• A fiber breakout cable offers a rugged cable design for shorter network designs. This may include LANs, data communications, video systems, and process control environments.

Advantages of Fiber Breakout Cable

• Fiber breakout cable is extremely versatile and suitable for use in riser and plenum indoor applications. You can use it in backbone and horizontal runs.
• Each fiber is individually reinforced, so you can divide a breakout cable into individual fiber lines, which enables quick connector termination and eliminates the need for patch panels.
• Fiber breakout cable can be more economical because it requires much less labor to terminate. You may want to choose a cable that has more fibers than you actually need in case of breakage during termination or for future expansion.
• Fiber breakout cable offers advantages over standard patch cords because it eliminates the need for a fiber-optic ducting system.

Applications of Fiber Breakout Cable

Fiber breakout cables are typically used for indoor applications, between an optical distribution frame and an electronic equipment rack, or between two electronic equipment racks. These cables are particularly effective when equipment racks are distributed over a large area (for example several floors in a large building). The end of the breakout cable behaves like a standard single pigtail. The outer jacket of the cable can be stripped. Fiber breakout cables are used to carry optical fibers that will have direct termination to the equipment, rather than being connected to a patch panel. Covered with an outer jacket, these cables are ideal for routing in exposed trays or any application requiring an extra rugged cable that can be directly connected to the equipment. And they are also suitable for pre-terminated cable assemblies.

Conclusion

Fiber breakout cables are ideal for installations requiring an extremely rugged and reliable cable design where maximum mechanical and environmental protection are necessary. And fiber breakout cables have many obvious advantages, such as cost savings, direct termination to sub cable, which eliminates the need for patch panels and patch cords and reduces connector loss, and easy installation and high crush resistance.

Overview of SFP+ Direct Attach Copper Cable

SFP+ direct attach copper cable assembly is a high speed and cost-effective alternative to fiber optic cables in 10G Ethernet applications. 10g copper SFP is suitable for short distances, and ideal for highly cost-effective networking connectivity within a rack and between adjacent racks. It enables hardware OEMs and data center operators to achieve high port density and configurability at a low cost and reduced power requirement. SFP+ direct attach copper cable has been a good solution. This post will provide you with some basic information about SFP+ direct attach copper cable.

Introduction

SFP+ direct attach copper cable, also known as twinax cable, is an SFP+ cable assembly used in rack connections between servers and switches. It consists of a high speed copper cable and two SFP+ copper modules. SFP+ copper modules allow hardware manufactures to achieve high port density, configurability and utilization at a very low cost and reduced power budget. SFP+ copper cable assemblies meet the industry MSA for signal integrity performance. The cables are hot-removable and hot-insertable, which means that 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. The following picture shows a Cisco SFP-H10GB-ACU7M compatible 10G SFP+ direct attach copper twinax cable.

Types of SFP+ Direct Attach Copper Cables

Generally, SFP+ direct attach copper cable assemblies have two types, SFP+ active direct attach copper cable and SFP+ passive direct attach copper cable.

SFP+ Active Copper Cable: SFP+ active direct attach copper cable assemblies contain low power circuitry in the connector to boost the signal and are driven from the port without additional power requirements. The active version provides a low cost alternative to optical transceivers, and are generally used for end of row or middle of row data center architectures for interconnect distances of up to 15 meters.

SFP+ Passive Copper Cable: SFP+ passive direct attach copper cable assemblies offer high-speed connectivity between active equipment with SFP+ ports. The passive assemblies are compatible with hubs, switches, routers, servers, and network interface cards (NICs) from leading electronics manufacturers like Cisco, Juniper, etc.

Applications of SFP+ Direct Attach Copper Cables

• Serial data transmission
• Network Interface Cards (NICs)
• Data center cabling infrastructure
• Fibre Channel over Ethernet: 1, 2, 4 and 8G
• 10Gb Ethernet and Gigabit Ethernet (IEEE802.3ae)
• High density connections between networking equipment
• High capacity I/O in storage area networks, and storage servers
• InfiniBand standard SDR (2.5Gbps), DDR (5Gbps) and QDR (10Gbps)
• Switched fabric I/O such as ultra high bandwidth switches and routers

FAQs of SFP+ Direct Attach Copper Cables

1. Whether active or passive cable assemblies are required?
Active cable assemblies have signal amplification and equalization built into the assembly. They are typically used in host systems that do not employ EDC. Passive cables have no signal amplification in the assembly and rely on host system Electronic Dispersion Compensation (EDC) for signal amplification/equalization.

2. What are the performance requirements for the cable assembly?
Both SFP+ active and passive copper cable assemblies should meet the signal integrity requirements defined by the industry MSA SFF-8431.

3. What cable length and wire gauge are required?
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. Smaller wire gauges results in reduced weight, improved airflow and a more flexible cable for ease of routing.

4. Are there any special customer requirements?
Examples of special customer requirements include: custom cable lengths, EEPROM programming, labeling and packaging, pull tab length and color, company logo, signal output de-emphasis, and signal output amplitude. You can order custom cables to your specific system architecture.

Conclusion

Fiberstore SFP+ twinax copper cables are available with custom version and brand compatible versions. All of them are 100% compatible with major brands like Cisco, HP, Juniper, Enterasys, Extreme, H3C and so on. Both passive twinax cables in lengths of 1, 3 and 5 meters, and active twinax cables in lengths of 7 and 10 meters are available. And the lengths can be customized up to the your requirements. You can get high quality compatible SFP+ cables and worldwide delivery from Fiberstore.

25GbE Cabling vs 40GbE Cabling

In recent years, 40 Gigabit Ethernet (GbE) has gained more popularity and the market of 40GbE is encouraging. But with the rapid growth of the new standard 100GbE, a new voice is announcing, namely 25GbE. As the increasing bandwidth requirements of private and public cloud data centers and communication service providers, 25GbE will to have a significant impact on server interconnect interfaces. Now you have two upgrade paths to 100G, 10G-25G-100G and 10G-40G-100G. Which one to choose? This post will make a comparison of 25GbE and 40GbE cabling, hoping it can help you make an appropriate decision.

25GbE Cabling Overview

25GbE is a standard developed by developed by IEEE 802.3 task forces P802.3by, used for Ethernet servers and switches connectivity in a datacenter environment. The single-lane design of 25 GbE gives it a low cost per bit, which enables cloud providers and large-scale data center operators to deploy fewer switches to meet the needs while still scaling their network infrastructure.

25GbE physical interface specification supports two main form factors, SFP28 (1×25 Gbps) and QSFP28 (4×25 Gbps). 25GBASE-SR SFP28 is an 850nm VCSEL 25GbE transceiver available in the market. It is designed to transmit and receive optical data over 50/125µm multi-mode optical fiber (MMF) and support up to 70m on OM3 MMF and 100m on OM4 MMF (LC duplex). In fact, using an SFP28 direct attach copper (DAC) cable for switches direct connection is a preferred option now. In addition, a more cost-effective solution is to use a QSFP28 to 4xSFP28 breakout cable to connect a 100GbE QSFP28 switch port with four SFP28 ports. DAC cable lengths are limited to three meters for 25GbE. Thus, active optic cable (AOC) solutions are also used for longer lengths of applications.

40GbE Cabling Overview

40GbE is a standard developed by the IEEE 802.3ba task force. The official development of 40GbE standards first began in January 2008, and were officially approved in June 2010. At the heart of the 40GbE network layer is a pair of transceivers connected by a fiber optic cable, OM4 or OM3 fiber cable. Fiber optic transceivers are plugged into either network servers or a variety of components, including interface cards and switches.

There are several standard form factors of 40GbE transceivers in the whole evolution. The CFP (C form-factor pluggable) transceiver uses 12 Tx and 12 Rx 10Gbps lanes to support one 100GbE port, or up to three 40GbE ports. With its large size, it can meet the needs of single-mode optics and can easily serve multi-mode optics or copper. But it is gradually falling behind since the increasing demand for high density. Another form factor is the CXP. It also provides twelve 10Gbps lanes in each direction, but is much smaller than the CFP and serves the needs of multi-mode optics and copper. At present, the most commonly used 40GbE form factor is the QSFP+ (quad small form-factor pluggable plus). It has the similar size with CXP but can provide four Tx and four Rx lanes to support 40GbE applications for single-mode, multi-mode fiber and copper.

Fiber optic cabling and copper cabling are both available for 40 GbE. The supportable channel length depends on the cable and the transceiver type. For data center 40GbE fiber optic cabling, OM3 and OM4 multi-mode cables are generally recommended because they can support a wider range of deployment configurations compared to copper solutions, and lower costs compared to single-mode solutions. MPO/MTP connectors are used at the multimode transceivers to support the multifiber parallel optics channels. For copper solutions, you can use QSFP+ direct attach copper cables, such as Cisco QSFP+ breakout cable. There are a lot of options, both active and passive, like Cisco QSFP-4SFP10G-CU5M compatible 40G QSFP+ to 4x10G SFP+ passive direct attach copper breakout cable (as shown below).

25GbE Cabling vs 40GbE Cabling

Compared to 40 GbE, 25GbE seems to be more suitable and cost-effective for cloud and web-scale data center applications. Using 25GbE with QSFP28 transceivers, users can deliver a single-lane connection, similar to the existing 10GbE technology but with 2.5X faster performance. In addition, 25GbE can provide superior switch port density by requiring just one lane (vs. 4 lanes with 40 GbE). Thus, it costs less and requires lower power consumption. Benefits of 25GbE compared to 40GbE are shown as below:

• Greater port density vs 40 GbE (one lane vs. four lanes)
• Maximum switch I/O performance and fabric capability
• Lower cost versus 40 GbE
• Reduced capital expenditures (CAPEX) and operational expenditures (OPEX)
• Fewer ToR switches and fewer cables
• Requires less power, cooling, and footprint
• Leverage of the existing IEEE 100GbE standard

Summary

25GbE seems to be a preferred option in the next step. It can provide up to 2.5 times faster performance than the existing 10GbE connections while maximizing the Ethernet controller bandwidth/pin and switch fabric capability. It can also provide greater port density with lower cost compared to 40GbE solutions. The trend will always be wider band and higher speed and port density. 25GbE or 40 GbE, let’s wait and see how things play out.

Several Commonly Used SFP Transceivers

Optical transceiver module is a device which can transmit and receive light and electrical signals in fiber optic networks. An optical transceiver generally has two ports, one for converting electrical signal into light signal and the other for changing light signal into electrical signal. Based on different data rates, there are many different kinds of transceiver modules, such as SFP (small form-factor pluggable), SFP+ (small form-factor pluggable plus), QSFP+ (quad small form-factor pluggable plus), CFP (C form-factor pluggable). Among them, SFP optical transceiver is a compact and hot-pluggable transceiver widely deployed for the Fast Ethernet and Gigabit Ethernet, for example, Cisco GLC-SX-MM compatible 1000BASE-SX SFP transceiver, as shown below, can support data rate up to 1000Mbps. In this post, a brief introduction to several commonly used SFP transceivers will be given.

CWDM SFP

Coarse wavelength division multiplexing (CWDM) SFP is made up of three parts: an uncooled laser transmitter, a PIN photodiode integrated with a trans-impedance preamplifier and a MCU control unit. It is an economical technique to save fiber resources through transmitting multiple wavelengths on one optic fiber. CWDM SFP is a kind of single-mode transceiver used for Gigabit Ethernet and Fibre Channel applications. The wavelengths of CWDM SFP are between 1470nm and 1610nm distinguished by different colors. Most commonly used CWDM SFP transceivers include CWDM SFP 1470, CWDM SFP 1490, CWDM SFP 1510, CWDM SFP 1530, CWDM SFP 1550, CWDM SFP 1570, CWDM SFP 1590, and CWDM SFP 1610, etc. CWDM SFP can support high performance of 1.25Gbps data rate and 80km transmission distance.

DWDM SFP

Dense wavelength division multiplexing (DWDM) SFP is a type of hot-pluggable transceiver used for Gigabit Ethernet which gathers different wavelengths onto one single fiber. Compared with CWDM SFP, DWDM SFP has a more intensive wave spacing for a high performance of data communication. The working wavelength of DWDM SFP ranges from 1525nm to 1565nm or 1570nm to 1610nm. The wave intervals are varied in 0.4 nm, 0.8 nm, 1.6 nm, etc. And the port of DWDM SFP transceiver uses SFP interface for over 1 gigabit optical data transmission.

BiDi SFP

BiDi SFP is short for Bi-Directional SFP. The core technology of BiDi SFP transceiver is the BiDi technique which enables bidirectional transmission of two different waves. BiDi module has only one port, and it must be deployed in pairs. For example, when a BiDi SFP module is used for receiving 1310nm and transmitting 1550nm optical signals, the other should receive 1550nm and transmit 1310nm signals, and vice versa. BiDi SFP transceiver usually costs twice the price of common SFP transceivers, but it is a better way to save the expenditure spent on optical fiber. BiDi transceivers have the advantage of reducing fiber cabling infrastructure costs by lowering the number of fiber patch panel ports, decreasing the amount of tray space dedicated to fiber management, and using less fiber cable.

FC SFP

Fibre Channel (FC) SFP uses the technology of fiber channel for high speed optical signal transmission with a data rate up to 4.25 Gbps. Fiber channel is a mature technology for serial interface standardized by American National Standards Institute (ANSI). It is applied to the connection between the storage controller and computer drivers. Nowadays, FC has played as a replacement for the Small Computer System Interface (SCSI) in high-performance storage systems, because fiber channel is faster in transmission speed and more flexible in the transmitting mode with or without fiber in accordance with the transmission range.

SONET/SDH SFP

Synchronous optical networking (SONET) SFP or synchronous digital hierarchy (SDH) SFP is a kind of transceiver based on the SONET/SDH standard. SONET/SDH is the physical standard for fiber optic transmission, first brought out by Bellcore in 1980s and then standardized by American National Standards Institute (ANSI) for popularization all over the world. SONET/SDH standard mainly stipulates the transmission rate, fiber interface, operation and maintenance in optical fiber transmission. SONET/SDH SFP transceivers can support OC-3 (up to 155.52 Mbps), OC-12 (up to 622.08 Mbps), and OC-48 (up to 2488.32 Mbps) data rates for multimode, short-reach, intermediate-reach, and long-reach applications.

Conclusion

SFP modules are found in Ethernet switches, routers, firewalls and network interface cards. With advantages of low cost, low profile, and the ability to provide a connection to different types of optical fiber, SFP modules provide the related equipment with enhanced flexibility. SFP transceivers are hot-pluggable small form factors used for 100BASE and 1000BASE Ethernet data transmission. There are different types of SFP modules, including BiDi SFP, CWDM SFP, DWDM SFP, SONET/SDH SFP and FC SFP. Each of them supports different techniques, which brings convenience to data communication.

Things to Know About Fiber Patch Cable Management

Deploying fiber optic jumper cables is just the first step to meet the high-bandwidth requirements, and efficient and strong management over those fiber optic patch cords is the basic requirement for a successful fiber optic network infrastructure. To deliver and guarantee the optimal network performance, fiber patch cable management is critical. Good management can lower operation cost and time, and increase the reliability and flexibility of network operation and maintenance. This post will help you better understand fiber patch cable management.

Factors to Consider

To get a flexible and well-organized fiber patch cable management, you need to take several factors into consideration.

Bend Radius

Compared with copper, optical fiber, usually made of glass, is much more fragile and need more protection and attention during the operation and management. Bend radius of an optical fiber will impact its reliability and performance. If a fiber cable is bent excessively, optical signals within the cable may refract and escape through the fiber cladding, causing loss of signal strength, also known as bend loss. Bending, especially during the installation and pulling of fiber optic patch cable, may also cause micro cracks and damage the fiber permanently. There are generally two basic types of bends, which are microbends and macrobends, as shown in the following picture.

Note that bend radius might not be seen during the initial installation of fiber patch cables. Because the number of fiber patch cables routed to the optical distribution ODF is usually small. When more fiber patch cords are added on the top of installed fiber patch cables later, problems will show up (shown in the following picture). A fiber patch cable which works fine for years might suddenly have an increased level of attenuation, as well as a potentially shorter service life.

Path of Fiber Patch Cable

Fiber patch cable path, which can affect the performance and maintenance of fiber patch cables, is an aspect closely related to bend radius. The path of fiber patch cable should be clearly defined and easy to follow. Improper cable routing can cause increased congestion in the termination panel, increasing the possibility of bend radius violations and long-term failure. Well managed fiber patch cable path ensures that bend radius requirements are maintained at all points and makes access to individual fiber patch cable much easier, quicker and safer, especially for those fiber patch cables with different types of connectors on the two ends, such as SC to LC fiber cable, or LC to ST fiber patch cable. Well-organized fiber patch cords can also help to decrease operating costs and the time required to turn-up or restore service.

Accessibility of Fiber Patch Cable

Accessibility of the installed fiber patch cable is also a factor that you need to take into consideration. If installed fiber patch cables are easy to access, the maintenance and operation would be quick without inducing a macrobend on an adjacent fiber, and it can also offer proper bend radius protection. Accessibility is critical during network reconfiguration operations and directly impacts operation costs and network reliability.

Tips for Management

According to those mentioned aspects which can affect the performance and maintenance of fiber optic patch cables, here are several tips that can help to increase the performance of fiber patch cords and the reliability and flexibility of fiber patch cable management.

• 1. Pay attention to the bend radius of fiber patch cables. Generally, for 1.6mm and 3.0mm fiber patch cords the minimum un-loaded bend radius is 3.5cm. The minimum bend radius of MPO cable is ten times the cord diameter.
• 2. Never pull or stress fiber patch cords. During the patching process, excessive force can stress fiber patch cables and connectors attached to them, thus reducing their performance. There might be something wrong if you need to use force in pulling a cord.
• 3. Routing fiber patch cords through cable pathways, so as to ensure there are no tangles, kinks or strains in the cords. For efficient routing, find the best path between the ports to be connected, avoiding routing cords through troughs and guides that are already congested.
• 4. Bundling and tying fiber patch cords gives the panel a neat appearance but tight bundling increases the risk of pinching. Do not tighten cable ties beyond the point where individual cord can rotate freely.
• 5.Labeling is necessary. At any administration point in a cabling infrastructure, including patching panels, accurate labels are essential. These will identify pair modularity and tell technicians where the other end of the cable is terminated.
• 6. Inspect fiber patch cords for physical damage including stress marks from sharp bends on the sheath, or damage to connectors.

Conclusion

A successful fiber patch cable management can increase the reliability and flexibility and decrease the cost of network operation and maintenance. To achieve successful fiber patch cable management, you need to consider and ensure bend radius protection, reasonable patch cable paths, and easy accessibility to fiber patch cables. When those factors are satisfied, it is already half the success to strong fiber patch cable management.

Armored Fiber Patch Cable Overview

Fiber optic jumper cables, as one of the most common component in fiber optic networks, are a transmission medium used to transmit data via light. There are many types of fiber optic jumper cables. For example, by fiber optic cable types, there are single mode patch cable and multimode patch cord; by optical connector, there are ST ST fiber patch cable, LC SC fiber patch cable, and so on; and by fiber optic cable jacket, there are PVC and LSZH fiber patch cords. And you can even order custom fiber patch cables with custom lengths and colors. In this post, a type of fiber patch cord, armored fiber patch cable, will be introduced.

Structure

The outer sleeve of armored fiber patch cable is usually made of plastics, like polyethylene, to protect it against solvents and abrasions. The layer between sleeve and inner jacket is an armored layer made of materials that are quite difficult to cut, chew and burn. Besides, this kind of material is able to prevent armored fiber patch cable from being stretched during cable installation. Ripcords are usually provided directly under the armored and the inner sleeve to aid in stripping the layer for splicing the cable to connectors or terminators. And the inner jacket is a protective and flame retardant material to support the inner fiber cable bundle. The inner fiber cable bundle often includes structures to support the fibers inside, like fillers and strength members. Among them, there is usually a central strength member to support the whole fiber cable.

Features

Armored fiber patch cable, as a member of fiber optic jumper cables family, it retains all the features of standard fiber patch cables. Compared with those common patch cables, armored fiber patch cables are much stronger and tougher. For example, once stepped by an adult, standard patch cables may get damaged easily and fail to work normally. But armored fiber patch cables can withstand the pressure and perform well. Armored fiber patch cables are rodent-resistant, which means that you don’t need to worry about rats biting the cables.

Basically, armored fiber patch cables offer benefits and features of traditional fiber patch cables, but they are with the production and durability of armor. Armored fiber patch cables allow high flexibility without causing damage, which proves to be helpful especially in limited space. Moreover, armored fiber patch cables offer an ideal option for harsh environments without adding extra protection. Apparently, they provide an efficient solution for many fiber cable problems such as twist, pressure and rodent damage.

Types

There are mainly two types of armored fiber patch cable, indoor armored fiber patch cable and outdoor armored fiber patch cable.

Indoor armored fiber patch cable is used for indoor applications. It consists of tight-buffered or loose-buffered optical fibers, strength members and an inner jacket. The inner jacket is commonly surrounded by a spirally wrapped interlocking metal tap armor. As the fiber optic communication technology develops rapidly with the trend of FTTX, there is a fast growing demand for installing indoor fiber optic cables between and inside buildings. Indoor fiber patch cable experiences less temperature and mechanical stress. Besides, it can retard fire effectively, which means it only emits a low level of smoke in the face of fire.

Outdoor armored fiber patch cable is designed to ensure operation safety of the fiber in complicated outdoor environments. Most outdoor armored fiber patch cables are loose buffer design, with the strength member in the middle of the whole cable, loose tubes surrounding the central strength member. Inside the loose tube there are waterproof gels filled, the whole cable materials and gels inside the cable between different components (not only inside the loose tube) help make the whole cable resist water. The combination of the outer jacket and the armor protects the fibers from gnawing animals and damages that occur during direct burial installations.

Applications

Armored fiber patch cable is generally adopted in direct buried outside plant applications where a rugged cable is needed for rodent resistance. It has metal armor between two jackets to prevent from rodent penetration. Armored fiber patch cables can withstand crush loads well. Another application of armored fiber patch cable is in data centers, in which cables are installed under the floor where it can be easily crushed. Single or double armored fiber patch cable is typically used underwater near shores and shoals. And armored fiber patch cords are also used in customer premises, central offices and in indoor harsh environments. They can provide flexible interconnection to active equipment, passive optical devices and cross-connects.

Conclusion

In summary, when transmitting data or conducting power in harsh environments, protecting your cables is crucial to safe and reliable operation. This is where armored fiber patch cables come into play. Armored fiber patch cables are used in applications where cables will be exposed to mechanical or environmental damage under normal operating conditions.