Fiber Optic Tech

Why Recommend Fiber Over Copper in 2017?

2017 is coming in less than a month, looking back, in the communication field, the old remaining dilemma between fiber and copper is still left behind. People are struggling about whether they should hold on to the tried-and-tested copper cables that are sufficient so far, or make the leap into the future, and go fiber optic. From a technical perspective, the case for switching to fiber is growing ever stronger. Using a fiber system will lead to more bandwidth, reliability, less down time and end up saving you money. Today’s article will make you understand the trend for switching to fiber.

fiber-optic-over-copper-cable

More Bandwidth, Faster and Longer

People are aware that fiber optics is winning out over copper because of its higher performance, namely more bandwidth, faster speed and longer link distance.

Bandwidth decides how much data you can receive and send. Copper cable that can be used for 10 Gigabit cabling, and 100 Gigabit cables is at the point of topping out, but these data rates can be sent only for very short distances between servers in data centers. While with fiber you can transmit more data over greater distances, and if you’re preparing for fiber now, you’ll also start to see remarkable differences in the not too distant future.

copper-vs-fiber

Have you ever though of the reason why fiber can transmit at higher speed for longer distances then copper cables? In short, copper cable uses the electric waves to carry the signal data, the phrase of the wave are modulated in sophisticated patterns to try and send as much data as possible through the continuous signal. This works well for low amount of data, but the copper cable will start to break down if you get to higher bandwidths and greater distances. As for fiber cable, it uses light to carry signals with transmitters and receivers at both ends. Light loses much less power than an electrical signal, so fiber can send data over much greater distances.

Fiber is More Reliable Than Copper

Besides the above reasons, another big reason that makes enterprises choose to use fiber other than copper is the reliability of the fiber optic system. If you put too many copper wires in close proximity, or just put them near any significant power sources, the signals can be easily interfered and read by others. Brazilian E-Voting machines were compromised using Van Eck Phreaking, with hackers able to read secret votes through these side-band electronic-magnetic emissions from the machines.

But fiber doesn’t suffer from the same problems as copper, so maintenance issues are rare. You can put multiple fiber optics next to each other and there won’t be any interference, and you can route them wherever in your building and they’ll still work perfectly. In fact, fiber can be routed through a building near power line conduits without any degradation of the signal. Therefore, it is not the good choice to still stay at copper wire because of its crosstalk where data from one wire gets mixed up with data on another.

Fiber is Safer

There are also safety issues, for people and equipment, with copper cabling which are no doubt at the forefront of your tech’s mind when they are telling you to go for a fiber installation. Any misconfiguration of your system, or out of the blue power surge, and having everything wired together with copper suddenly becomes a serious problem. For example, a lightening strike jumped through copper cabling between buildings, can destroy all the electrical equipment in both buildings.

Light doesn’t leak, and if it does you’ll know about it. Someone splicing into the fiber will leave a tell-tale signal as the attenuation will drop, just as when fiber is damaged. Using a testing technique called optical-time domain reflectometry, you can easily find where someone has spliced into the system and hunt the spies down!

In general, it’s also easier to test if something does goes wrong. The way light travels through glass is better understood than how electricity flows through copper, so any diagnostics are straightforward.

Fiber is More Flexible Than Copper

Fiber optic cable is composed of a thin, flimsy strand of glass, which is very delicate, needing installation by specialists in white gloves. And it can be destroyed by any clumsy-fingered techie thereafter. However, it is stronger than copper cables (made of a thick cord of metal).

Even though the fiber optic cable is lightweight and thin, it can be pulled through buildings with more force than copper, and can take a dunking in water, and is more flexible so can negotiate tricky building geography. All the while being lighter and thinner than copper, so it can be installed with more ease anywhere in your building.

Because it’s so lightweight and thin, it takes up less space, and is easier to handle. If you want to scale a copper wired system then you need more and more of bigger and bigger cabling. With an optical system, there is almost no difference in size between the diameter and weight of different size fibers, and because a smaller fiber can carry so much more data than copper cables, you need less overall.

Fiber Will Cost You Less

When people suggest you switching to fiber, you might not think that they take budget into account, but in the long run, fiber optic system will cost your company less.

Because fiber is more resilient, there is less downtime on the network. Because of all the maintenance and legacy issues with copper wires, you’ll always have downtime while an ISP technician is down a manhole somewhere splicing together copper cables that have been damaged.

There’s also less hardware to go with the fiber optic system. Because data can be transmitted over fiber for longer distances, you don’t need the extra power boosters, junctions, and terminals that are needed for copper cabling. Your fiber can be brought directly to your office with no need for multiple connections.

Fiber is new technology that is constantly evolving and a hot area of research. We believe that in 2017, fiber optic based system will be more popular among users.

Telecom Cable Rating: CMP or CMR Cables

We usually use terms—CMP, CMR, PVC and LSZH to describe telecom cables, but do you know what these terms really mean? And, more importantly, which one does your project actually need? The article below will briefly outline many industry cable types, along with their features to help you have a better understanding of them.

Plenum Rated Cables

CMP cable refers to the communication plenum cable that is laid in the plenum spaces of buildings. Plenum rated cable or just plenum cable is jacketed with a fire-retardant plastic jacket of either a flame retardant low-smoke polyvinyl chloride (PVC) or a fluorinated ethylene polymer (FEP). Owing to its material in this network cable, it doesn’t emit a toxic smoke when they burn. Plenum rated cables are slower to burn and produce less smoke than other cables.

cmp

As seen in the above image, plenum refers to the air handling space. In a standard commercial building, the plenum is the space between the drop ceiling and the structural ceiling. In residential installations the plenum may include the space above the ceiling or under the floor when floor level air circulation is used. Plenum rated cable is mandated to be installed in any “air handling” space because of its low smoke and low flame characteristics.

Riser Rated Cables

CMR cable refers to the communication riser cable that is run between floors in non-plenum areas. The term ”riser” usually refers to a space that runs between floors in an office or a commercial building. The fire requirements on riser cable are not as strict as plenum cables. It will emit toxic fumes when burning. This is considered to be a slight problem, but it is not enough to warrant consideration as long as these cables are not used in ducts.

riser-rated-armored-cable

These cables can be used for both commercial and residential spaces but are generally used more for residential homes. For example, riser cables can be used from room to room, as long as it is run around baseboards, along bottoms of walls, and along the tops of walls. They can also be used to run cables from the basement to the upper floor, as long as the cable does not need to pass through an air duct.

How Do I Know Which One Should I Choose?

Many customers has asked about this question, unfortunately we cannot help or advise you as each individual cabling details has to be evaluated. However, for those who plans to wire their house with cat 5e or cat6a cable, we do have some practical suggestions for you to choose between plenum and riser rated cables.

Both plenum and riser cables commonly include a rope or polymer filament with high tensile strength, which helps support the weight of the cable when it is dangling in an open chute. Cables like twisted-pair, coaxial, HDMI, and DVI are available in both plenum and riser versions. The cable cost is often significantly higher than general-use cable due to the special restricted-use flame retardant materials. Plenum cable is expensive, much more expensive than riser rated cable. Additionally the practice of running cables in plenum spaces is becoming less popular, and therefore demand for plenum rated cable is much less than riser rated cable.

However, the plenum rated cables have a higher fire rating than riser cables. Thus, plenum cable can always replace riser cable, but riser cable cannot replace plenum cable in plenum spaces. The stiffness of CMR cable is less than that of CMP cables. This means CMR cable is easier to bend around corners of baseboards and ceilings. This can allow a tighter fit against corners to minimize the look of cables. The following two pictures shows the burning test of these two cables.

cmp-burn-test-result

cmr-burn-test-result

One final tip to keep in mind is that If you will never need to run it through air-handling ducts/spaces, just get Riser rated. But, for retrofits, that’s often the easiest route from basement to the upper floors and sometimes a few basement ceiling joist spaces are covered over with tin to use as inexpensive cold air return ducts. If you have to go through those, Plenum rating is required, too. If there’s ever a hot enough fire to melt CMR’s covering, any toxic fumes it might emit will be among the least of your worries. but the Riser rating means its fire-resistance will keep the flames from following it between floors.

Conclusion

Selecting the right type of cable for your home network is important; CMP cable is usually recommended as it is safer to use in case of fire, even though they are more expensive and stiffer than CMR cabling and more difficult to bend. But if you are not up to run cables through air duct, CMR cable is actually a great choice, as this type of cable is less expensive and easy to install in a network. FS.COM is committed to offer the most cost-effective cabling solutions to our clients. Our cat 5, Cat 5e, cat 6 cables are available in both plenum and riser version. If you have any interest, please feel free to visit fs.com.

The Truth About OS1 and OS2 Optical Fiber

Several years ago, OS1 fiber optic cable was the only one standard for single-mode fiber with the maximum link length for campus cabling around 10km, but 10km can no longer satisfy people’s increasing needs nowadays. Therefore, OS2 fiber that can support much longer distance than 10km has been widely utilized in telecommunication industry. But there has been some debate and confusion as to the differences between OS1 and OS2 fiber types and what the terminology actually means. Thus, the following article is provided to assist the users in understanding the differences between OS1 and OS2 fiber types. The following image shows the LC to LC fiber patch cable single mode plugging in a switch.

single-mode-fiber

OS1 and OS2 Single-mode Fibers

Firstly, OS in the term OS1 and OS2 specifications refers to the Optical Single-mode fiber. Single-mode OS1 is indoor tight buffered fiber. An OS1 cable could be a micro-core LSZH indoor cable that consists of 250 micron fibers, with the fibers being tightly enclosed in a cable with aramid strengthening yarn and a LSZH jacket. The attenuation of a OS1 fiber is higher than an OS2 fiber. From the above table, the maximum attenuation allowed per km of installed cable is 1.0 dB for OS1 for 1310nm and 1550nm, while the maximum attenuation allowed per km of installed cable is 0.4 dB for OS2 for 1310nm and 1550nm.

os1-and-os2-maximum-attenuation

Single-mode OS2 is an outdoor loose tube optical fiber cable, which is suitable for outdoor applications where the cabling process applies no stress to the optical fibers. For instance, a 250 micron coated multi-fiber, which is loose inside an enclosure or tube and/or is free to move, is classified as OS2.

OS1 or OS2 performance cables are constructed from B1.3 optical fibers (or ITU specification G.652D). Furthermore, OS1 and OS2 cable types can also include cables manufactured from B6_A fiber, which is commonly known as bend insensitive single-mode optical fiber, or ITU specification G657A2 (compatible with B1.3 optical fiber). OS1 or OS2 single mode fiber performance, does not relate to ITU specification G.655 (Non-dispersion shifted single mode optical fibers.

Why Should We Use OS2 Over OS1 Fiber?

Single-mode fiber was mainly used for long-hual applications but not marked as a cost-effective investment for future application in building. One reason is that the single-mode related products like cables and optical transceivers are offered with high price. The other is that with the price decrease of the VCSEL or laser power source, the performance gap (namely link length) between multimode or single-mode fiber is smaller everyday.

Considering this, why not use the best single-mode fiber (OS2) to create better performance and ready for high speed data networks? Besides the difference in link distance, OS1 and OS2 fibers have different attenuation—OS2 has two times less losses than OS1 fibers.  And in CWDM or DWDM network, OS1 has poor result in the wavelength range called E-band or water peak band, which makes it not suitable for the WDM-based network.

cwdm-allocation-and-fiber-loss

Figure 3: CWDM wavelength allocation and fiber loss. The solid line represents OS2 fibers. The dotted line represents the water peak.

Another good news is that if you use OS2 fiber, it will be more suitable for you to support the IEEE 802.3 multiplexed series (40G BASE-LR4 and 100G BASE-ER4). You even don’t need to change your existing OS1 fibers, as the OS2 can be mixed with OS1 in the same link. What’s more, active or passive component for OS1 like connectors, adapters also works with OS2.

Conclusion

To sum up, OS1 optical fiber is appropriate for indoor and universal tight buffered cable constructions, which are mainly deployed in internal building/campus networks, as well as internal cabling within telecommunication exchanges and data centers. While OS2 optical fiber is appropriate for outdoor and universal loose tube solutions, which would include external plant and most back-haul networks. Therefore, when deciding which single-mode optical fiber type to specify, consider the application as well as how and where the cable will be installed. For further information on optical fiber products, please contact FS.COM. Our fiber optic cable price is the cheapest with great feedback.

Cisco SFP Transceivers Overview

Cisco Small Form-Factor Pluggable (SFP) transceiver can be defined as a device that comprises of both a transmitter and a receiver of analog or digital signals. It is a compact, hot swappable, input/output device based on the available fiber cable type (copper cable or multimode/single-mode optical fiber). In addition, SFP transceivers can be leveraged both at 100Base and 1000Base rates in the following standards:

sfp-standard

SFP transceivers are mainly used to link equipment in telecommunication and data communications like switches and routers. They support applications like 2G/4G Fiber Channel, SONET/SDH Network, Gigabit Ethernet, High-speed computer links, and with CWDM and DWDM interfaces. Today’s article will generally introduce the Cisco SFP transceivers including the Cisco 100M SFP, Cisco 1000BASE SFP, CWDM/DWDM SFP, SONET/SDH SFP as well as Cisco BiDi SFP to you.

Cisco 100Mbqs SFP

Cisco offers two different types of 100BASE SFP—100BASE SFP for Fast Ethernet (FE) SFP Port and 1000BASE SFP for Gigabit Ethernet (GE) port. Besides the above standards, the Cisco 100BASE SFP portfolio includes 100BASE-FX, 100BASE-LX, and 100BASE-BX SFPs.

Cisco 100BASE-FX SFP operates on MMF for link spans of up to 2km. 100BASE-LX SFP operates on SMF up to 10km. 100BASE-BX SFP operates on SMF for a link length of up to 10km. A pair of a 100BASE-BX-D and a 100BASE-BX-U SFP is needed for the single strand deployment. The following table displays the compatible Cisco 100M and 1G SFPs from FS.COM.

cisco-sfp

Cisco 1000BASE SFP

Cisco 1G SFP transceivers offer a convenient and cost-effective solution for the adoption of Gigabit Ethernet and Fibre Channel in data center, campus, metropolitan area access and ring networks, and storage area networks. They are available in several Gigabit standards—1000BASE-T, 1000BASE-SX, 1000BASE-LH, 1000BASE-EX, etc. Take Cisco GLC-LH-SM as an example, it operates over standard single-mode fiber spanning distances of up to 10 km and up to 550 m over any multimode fiber (OM3/OM4). If 1000BASE-LX/LH SFP transceiver transmits in the 1300nm wavelength over OM1/OM2 fiber, it requires mode conditioning patch cables.

Cisco CWDM/DWDM SFP Modules

Cisco Coarse Wave Division Multiplexing (CWDM) solution allows scalable and easy-to-deploy Gigabit Ethernet and Fibre Channel services. Similar with traditional SFP module, the Cisco CWDM SFP is a hot-swappable input/output device that plugs into a SFP port or slot of a switch or router. CWDM SFP transceiver modules make use of the SFP interface for connecting the equipment and use dual LC/PC fiber connector interface for connecting the optical network with a link distance of up to 80km. It usually comes in 8 wavelengths covering from 1470 nm to 1610 nm. Color markings on the devices identify the wavelength to which the Gigabit Ethernet channel is mapped. The following picture lists the FS.COM compatible Cisco CWDM SFPs with their wavelengths and color codes.

cwdm-sfp

DWDM (Dense Wavelength-Division Multiplexing) SFP transceivers, however, are used as part of a DWDM optical network to provide high-capacity bandwidth across an optical fiber network. Cisco DWDM SFP is a high performance, cost effective module for serial optical data communication applications up to 4.25Gb/s. There are 32 fixed-wavelength DWDM SFPs that support the International Telecommunications Union (ITU) 100-GHz wavelength grid.

Cisco SONET/SDH SFP Modules

This Cisco SONET/SDH SFP is compatible with the SONET/SDH standards, and support the digital diagnostic functions specified in the SFF-8742 Multi-Source Agreement (MSA). Cisco SONET/SDH SFP can be directly plugged into a variety of ports on Cisco router interfaces. These SFP optics support OC-3, OC-12, and OC-48 data rates for multimode, short-reach, intermediate-reach, and long-reach (up to 80 km) applications just as seen in the below chart.

cisco-sonet-sdh-sfp-modules

Cisco BiDi SFPs

Bidirectional (BiDi) SFP transceivers can transmit and receive data to/from interconnected equipment through a single optical fiber. BiDi transceivers are fitted with wavelength division multiplexing (WDM) diplexers, which combine and separate data transmitted over a single fiber based on the wavelengths of the light. BiDi transceivers must be deployed in matched pairs, with their diplexers tuned to match the expected wavelength of the transmitter and receiver that they will be transmitting data from or to. These transceivers offer bi-directional data links over single-mode fiber up to 120 km.

Take 1000BASE-BX SFP BiDi transceiver as an example, 1000BASE-BX SFP modules are compliant with SFP Multi-Source Agreement (MSA) specification and SFF-8472, and conform to the IEEE 802.3ah 1000BASE-BX10 standard. 1000BASE-BX SFP modules include 1000BASE-BX-U SFP module and 1000BASE-BX-D SFP module. The 1000BASE-BX-D SFP operates at wavelengths of 1490nm TX/1310nm RX, and the 1000BASE-BX-U SFP operates at wavelengths of 1310nm TX/1490nm RX. These transceivers use standard simplex LC connectors for fiber cable connection and provide a long transmission distance of up to 10 km.

Conclusion

It is necessary to select the suitable SFP transceivers for your network. This article has concluded several types of Cisco SFP transceivers, which might be a great help for those who are looking for Cisco SFPs. FS.COM, a leading and professional fiber optic SFP transceiver module provider, has a large inventory of 1000BASE SFP, 100BASE SFP, CWDM/DWDM SFP, BiDi SFP, etc. If you have any needs of our transceivers, please send your request to us.

C3KX-NM-10G Network Module Overview

Questions like whether a 1G SFP can be used on the SFP+ port of the switch and support 10G data rate are frequently asked by overall users. Generally, you will get the answer “no”. Because Most (95+%) SFPs and SFP+s will only run at the rated speed, no more, no less. Even though SFP and SFP+ have the same port size, it doesn’t mean that you can insert a SFP in a SFP+ port to achieve a 10G connectivity. Not to mention that some SFP+ port can only support 10G SFP+ optics. However, this article will introduce a Cisco Network module in Cisco Catalyst 3750-X and 3650-X Series switches that can both support 1 GbE SFP and 10 GbE SFP+ transceivers.

C3KX-NM-10G Network Module

The Cisco Catalyst 3750-X and 3560-X series switches support four optional network modules for uplink ports, namely C3KX-NM-1G (four GbE port network module), C3KX-NM-10G (two 10GbE SFP+ ports network module with four physical ports with two SFP+ and two regular SFP ports), C3KX-NM-10GT (two 10GB-T ports network module), C3KX-SM-10G (service module with two 10GbE SFP+ ports network module for Netflow and MACsec encryption). C3KX-NM-10G module on the Cisco Catalyst 3750-X and 3560-X has two installation screws on each side, which make it easy to switch things out and make new connection without a fuss. What’s more, when business demands changes, the C3KX-NM-10G network module allows customers to only upgrade their modules from 1 GbE to 10 GbE without replacing a comprehensive upgrade of switch.

c3kx-nm-10g-module

As the above image shows, the C3KX-NM-10G network module has four slots—two SFP+ slots and two SFP slots. These four slots usually work in pair, with one pair supporting 1 GbE data rate and the other achieving 10 GbE. Note that you must use the same form factor transceiver in a pair and never mix the SFP module with SFP+ module. SFP+ can’t auto-negotiate down to 1G to support with SFP module.

To put it simply, let’s name the port from left to right as slot 1, slot 2, slot 3, slot 4. Usually a 10-Gigabit SFP+ module takes precedence over a 1-Gigabit SFP module. But it’s another case when an SFP module is first inserted in Slot 1 and has link. For example, if the SFP in Slot 1 retains link, you insert an SFP+ module in Slot 2 and it will not operate. If the SFP module in Slot 1 is shut down or removed, the SFP+ module in Slot 2 turns on. The SFP module in Slot 1 does not work as long as an SFP+ module is in Slot 2. The following chart concludes the accessible combination of SFP and SFP+ modules.

combination-method

Suitable Cisco Transceivers for C3KX-NM-10G Network Module

As note before, C3KX-NM-10G module on the Cisco Catalyst 3750-X or 3560-X series switch can both support 1 Gigabit Ethernet and 10 Gigabit Ethernet data links. We will list the available Cisco modules attached with detailed information in the below charts.

Cisco SFP transceiver for C3KX-NM-10G module:

cisco-sfp-for-c3kx-nm-10g-module

Cisco SFP+ transceiver for C3KX-NM-10G module:

cisco-sfp-for-c3kx-nm-10g-module

There are many other compliant Cisco SFP+ DAC and AOC cables that I haven’t listed above, if you are interested, you can visit fs.com.

Conclusion

This post lists all of the functions of the Cisco C3KX-NM-10G network module, all the basic and advanced features and tells you how to select the compliant Cisco SFP modules and SFP+ modules. If you want to expand your database from 1GbE to 10GbE, with the Cisco C3KX-NM-10G network module, you only need to upgrade your Cisco SFP and plug it with a brand new SFP+ transceiver, then that’s it.

Whether to Choose 40G DAC or AOC Cables

With the top trend for data center and enterprises to move to higher data rate like 40G, relevant products and technologies are developed to back this new speed (e.g. the 40G optical transceivers and cables). However, there are so many options out there on the market. Network users usually don’t know how to make a choice. Take the 40G cables as an example, the most commonly used 40G cables are the 40G direct attached cable (DAC) and active optical cable (AOC). Each has its unique specification and usage. Which would be the most suitable one for connecting signals across the rack in data center? This article will provide you an ideal answer from the aspect of cabling performance, transmission distance and cost.

Brief Overview of DAC and AOC Cables

QSFP DAC cable is a form of high-speed cable with “transceivers” on either end used to connect 40Gbqs switches to routers or servers. QSFP+ DAC cable usually comes in either active or passive versions. They are widely available for short-reach 40G interconnect (within 7 meter). 40G DAC cables transmit 40GbE over short distances of parallel coaxial copper cabling. It uses a special cabling assembly with four lanes of coaxial cabling. Each transmit 10 Gbps for a total data rate of 40 Gbps. QSFP to QSFP and QSFP to SFP+ cable are the two common types of 40G DAC cables. The picture below shows a QSFP to SFP+ DAC breakout cable connected in a switch.

qsfp-to-sfp-dac-cable

AOC cable uses electrical-to-optical conversion on the cable ends to improve speed and distance performance of the cable while mating with electrical interface standard. Compared with DAC cables, its smaller size, longer transmission distance, lower insertion loss and electromagnetic interference immunity make it popular among subscribers. 40G AOC cables (see in the image below) can support longer distance than QSFP+ DAC cables (within 15m).

qsfp-to-sfp-aoc-cable

Comparison Between DAC and AOC Cables

After the brief introduction to the DAC and AOC cables, what to be considered next is the detailed comparison from the expects of cost, distance and cabling performance. The following chart shows a vivid comparison between them.

comparison-between-dac-and-aoc-cables

Cost

Cost is typically the No.1 factor affecting your selection. When it comes to 40G DAC cables, it is the same, although it’s quite clear that copper is much cheaper than optical cable. AOC, with connectors embedded with electronics and/or optics is the most expensive one. But it supports the highest transmission distance, many data centers won’t choose it because of the high cost.

While passive copper cable is much cheaper than AOC. However, the truth is that it cannot support 40G transmission in most cases in data center. Active copper cable is less expensive than AOC and can support longer transmission than passive copper cable seems to be a good choice. In this battle over cost, passive copper cable wins. But it is not suggested for 40G transmission in most cases.

Power Consumption

The main reason why DAC active copper cable and AOC can support longer transmission distance than passive cooper cable is that they are supported with active electronics. Passive copper cable requires no power. For 40G transmission, the power required for active copper cable is about 440mW, which is much less than that of AOC—2W. Thus, passive copper cable wins for its low power consumption.

Cooling System

Cooling is always crucial for data center, as it is closely related to the data center reliability and life of use. During DAC cable selection, two main factors can affect the cooling of data center. One is cable size. the other is the power consumption of direct attached cable. For the former factor, the thinner the cable is, the better dispersion devices in data center would have. AOC cable is the thinner than DAC cables. And DAC active copper cable is also thinner than passive cooper cable. The relation between power consumption and data center cooling is easy to understand. Higher power consumption can generate more heat in data center, which will load more burden on the data center cooling system. As mentioned before. AOC cable needs the highest power and DAC passive copper cable needs the lowest.

Transmission Distance

In the past, when the data rate required is less than 5 Gbps, the passive copper cables are used for interconnection. This type of DAC connects two SFP connectors by a copper cable, providing direct connection between cable ends via copper wire. Thus they are not expensive and robust with reliability. As it is passive, they need no power generally. However, when it comes to 40Gbps, they cannot satisfy such data rate in most cases. The passive copper cable with QSFP connectors attached on both ends can only support transmission 40 Gbps over very short distance. Thus passive copper cable is not suggested for regular 40G interconnection, unless 40G transmission is in very short distance.

Then AOC cable is introduced to overcome this challenge. Optical cables are thinner, flexible and can reach much longer distance up to 100 meters or more, which is much longer than that of the passive copper cable. However, AOCs are usually very expensive with the connectors attached on the active optical cable are embedded with optics and/or electronics. The connectors of the DAC active copper cable are embedded with electronics. Although they cannot support transmission distance as long as AOC, active copper cable can support longer transmission distance than that of the passive copper cable via copper wire. 40G transmission distance of active copper cable is about 15 meters.

To sum up, if you have a special requirement of the transmission distance. Then active optical cable wins with a transmission distance up to 100 meters. The active copper cable got the second place. And passive copper cable is at the last place. It is only suggested for 40G transmission over really short distance.

Conclusion

After comparing the performance of the DAC and AOC cables, we understand that the DAC passive copper cable is only suitable for really short-reach applications. While AOC cable possesses the best transmission performance but with higher cost in both material and daily use, and it needs more power as well. As for the DAC active copper cable, it can can support 40G transmission up to 15 meters with low power consumption, and satisfy the regular interconnection requirement for distance and cooling in most data center. What’s more, it is less expensive. FS.COM offers a full range of 40G QSFP cables including 40G DAC cable and AOC cables. Besides, the QSFP transceivers are also provided.


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