Introduction to DAC Cables
DAC cables, or “Direct Attach Cables", are a kind of optical transceiver assembly widely applied in storage area network, data center, and high-performance computing connectivity etc. They are a form of shielded high speed cable with SFP connectors on either end. They can be used to connect switches to routers and/or servers. 
Before you purchase this product, a few things you need to know. Firstly, there are different versions of DAC cables. Generally Twinax cables less than 5 meters in length are passive and greater than 5 meters in length are active. The most common version is the “Passive Assembly” where the data cables are directly connected to the transmitting and receiving signal. Because this signal is not very strong, you can reach up to 5 meters with this setup depending on the switch or router. Another version is the active cable version that contains more sophisticated electronics where the transmitting power is amplified to give a better data-pulse. The third version is the “Active Optical Cable". Instead of using a high speed copper wire, this cable uses a hardened glass fiber for transmission. These glass fiber cables are becoming more widely used because of the issues associated with lower-end cables. The main issues are with the coding, if each end has to be connected to a different brand of router or switch, this can cause issues with compatibility. Another common issue is where the switch or router does not give enough power for a (long) passive cable. In this case, there are a lot of CRC errors or packet loss and unstable links—this can be solved by switching to active or active optical cables.
And there are different types of DAC connectors on the market. QSFP+ cables and SFP+ DAC cables are the two main connectors. Fiberstore supplies various kinds of high speed interconnect DAC cable assemblies including 10G SFP+ cables, 40G QSFP+ cables, and 120G CXP cables. The SFP+ DAC cables provide high performance in 10 Gigabit Ethernet (10GbE) network applications, using an enhanced SFP+ connector to send 10Gbps data through one paired transmitters and receivers over a thin twinax cable. SFP+ DAC cables have a fixed-length cable, typically 1 to 7 m (passive cables) or up to 15 m (active cables) in length, and, like 10GBASE-CX4, are low-power, low-cost and low-latency with the added advantages of using less bulky cables and of having the small form factor of SFP+. SFP+ DAC cables today is tremendously popular, with more ports installed than 10GBASE-SR. QSFP+ (Quad Small Form-factor Pluggable) DAC cables are designed for high-density applications that integrate 4 InfiniBand channels at 10 Gbps per lane. These cables are used for 40 GbE and InfiniBand standards to maximize performance. Recently DAC cables are becoming increasingly popular in the network industry, mainly because the price difference is so large when compared with regular optics. Another reason is that RJ-45 10G is not widely adopted, and most high density 10G switches are delivered with 48x SFP+ ports in 1 Rack Unit.
I believe that you have gained basic knowledge about DAC and I hope it will be useful for you. For more information not referenced here, please contact me or leave your message.
Things You May Feel Curious About CWDM Transceiver
WDM is a new technology which multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths of laser light. And in fiber-optic communications, Coarse Wavelength-Division Multiplexing (CWDM) is a convenient and cost-effective solution for the adoption of Gigabit Ethernet and Fiber Channel in campus, data-center, and metropolitan-area access networks, which has greater potential compared with DWDM (Dense wavelength division multiplexing). There are some things you may feel curious about CWDM transceiver, after going through this passage, you might have a clear understanding of CWDM transceiver.
1. What is the difference between CWDM transceiver and DWDM transceiver?
The main difference between CWDM transceiver and DWDM transceiver lies in the wavelength interval. The DWDM system’s wavelength interval is 0.2nm to 1.2nm, while CWDM possesses a much broader wavelength interval, and each wavelength band covers the five wave bands—O, E, S, C, L of single-mode fiber system. CWDM transceivers’s wavelength is 1270 nm, 1290 nm, 1310 nm, 1330 nm, 1350 nm, 1370 nm, 1390 nm, 1410 nm, 1430 nm, 1450 nm, 1470 nm, 1490 nm, 1510 nm, 1530 nm, 1550 nm, 1570 nm, 1590 nm, 1610 nm.
2. If my equipment doesn’t support CWDM or DWDM transceivers, how can I transport the signal over a WDM network?
The connector type is generally a function of the density of the transceiver. CWDM transceiver supports FC/APC, FC/UPC, SC/APC, SC/UPC, LC/UPC, LC/APC, etc. GBIC transceiver is larger than an SFP transceiver, the GBIC uses the larger “SC" style of connecter while the SFP/SFP+ transceiver uses the smaller “LC" style of optical connector. Many times the optical patch cables will need to have different connector styles at each end, and example is having a SFP (LC connector) installed in a router connected to a SC port on a patch panel.
3. Can you describe the basic capabilities of CWDM transceiver?
CWDM transceiver supports DFB Laser transmitter and its compliant receiver is PIN or APD. CWDM transceiver’s data rate is up to 2.7Gbps. And its operating temperature is between 0℃ and +70℃ with a distance up to 80km, which is compliant with SFP MSA SFF-8074i, digital diagnostic SFF-8472, Telcordia GR-468 and RoHS.
4. You might be curious about how to test CWDM transceiver since the coverage range of CWDM transceiver’s wavelength is very wide.
To be honest, it is relatively complicated to test it, but to put it simple you can use the following methods. One is that using the white light as testing light, and then using the scan spectrometer to test it. The other is that using the 1550 nm LED light as a testing light, and then using scan spectrometer, or you could use tunable laser light source as testing light, then use the PM detection. There are some merits and demerits in the above methods. You should use them flexibly and subject to availability.
5. Since the CWDM transceiver is a new product, it might encounter some problems during its development. What are they?
First, with respect to DWDM transceiver, the price advantages of DWDM transceiver is not competitive. DWDM transceiver also put great pressure on CWDM transceiver because it will form a complete metro DWDM network by using DWDM technology with good scalability. Besides, there are technical problems about the higher speed and longer transmission distance of CWDM transceiver.
A Brighter Future Is Embracing 100G Transceiver
Fiber works were out of people’s imagination in the ancient times, but now numerous optical products have emerged rapidly and facilitate people’s life. In the meanwhile, 100G transceiver has become possible and springs up like the mushrooms. The following passage will give a lead to 100G transceiver.
100G transceiver provides customers 100 Gigabit Ethernet connectivity options for data center networking, enterprise core aggregation, and service provider transport applications. 100G transceivers offer significant advantages over existing solutions in terms of reduced power dissipation and increased density with the added benefit of pluggability for reduced first installed cost.
100G Transceiver
CFP and CXP are the two common types of 100G transceiver. The CFP defines hot-pluggable optical transceiver form factors to enable 40 Gbit/s and 100 Gbit/s applications. CFP modules use the 10-lane CAUI-10 electrical interface. While CXP modules use the CAUI-10 electrical interface, which is a multi-source agreement to produce a common form-factor for the transmission of high-speed digital signals. CXP optical transceiver is hot pluggable, and supports data rates of 40 Gbps. The CFP transceiver, as detailed in the MSA, supports both single-mode and multi-mode fiber and a variety of data rates, protocols, and link lengths, including all the physical media-dependent (PMD) interfaces, which is targeted at the clustering and high-speed computing markets.
As we all know, 100 transceiver has a very short history. On July 18, 2006, a call for interest for a High Speed Study Group (HSSG) to investigate new standards for high speed Ethernet was held at the IEEE 802.3 plenary meeting in San Diego. And in June 2008 Cisco Systems and Comcast announced their 100GbE trials. In October 2008, Huawei presented their first 100GbE interface for their NE5000e router. And On February 16, 2015, the IEEE 802.3bm standard was approved. Since then, 100 transceiver achieves mass production and sales of 10G, 40G, and 100G transceivers for enterprise and data center applications grew rapidly in 2014.From the table below, We know that the market for 100G data center optics is accelerating, but it has yet to be turbocharged by widespread data center deployment in the way 40G transceiver has. And the popularity of 40G transceivers accounted for much of the upswing. Overall, the long-anticipated ramp of 100G transceiver may be at hand and the ongoing movement to 100G and price declines will put revenue pressure on both 10G and 40G. Major growth in the data center for 100 Gigabit Ethernet is on the horizon due to more service providers applying 100G transceiver equipment in their core networks and new silicon entering the market.
With these good prospect, I bet that next year is going to be huge for 100G transceiver. Our Fiberstore company is a professional manufacturer supplier of 100G transceiver. All of our 100G transceivers are tested in-house prior to shipping to guarantee that they will arrive in perfect physical and working condition. We guarantee our 100G transceiver to work in your system and all of our 100G transceivers come with a lifetime advance replacement warranty.
Are You Familiar With Single Mode Fiber?
Customers often feel puzzled about how to select between single mode fiber and multi mode fiber due to its similar function. While in 1980, Professor Huang Hongjia of the Chinese Academy of Sciences recognized that single mode fiber, compared to multi-mode fiber, has the characteristics of lower loss, narrower modal dispersion and have a higher bandwidth, which is ideal for medium capacity long-range communication system. At the same time he developed coupling wave theory in the field of microwave theory and successfully developed single mode optical fiber.
What is Single Mode Fiber?
Types of Single Mode Fibers
In order to get one step closer to understanding the Single mode fiber, common Single mode fiber must be explained before. Standard single mode fiber, dispersion shifted fiber , Non-Zero Dispersion Shifted Fiber are the most popular Single mode fiber in the industrial application. Each type provides unique benefits for device communication. Low water peak fiber is the most common single mode fiber used in our country. Non-Zero dispersion shifted fiber is a kinds of DSF. Its 1550nm dispersion is close to zero, but not zero. It is an improved dispersion-shifted fiber to suppress four-wave mixing. For your easy reference, a quick comparison chart listed below demonstrates the key differences of these three commonly used serial interfaces for industrial Applications.
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There are many different types of connectors of single mode fiber. LC Connector, FC Connector, SC Connector, ST Connector, MTRJ Connector, MU Connector, E2000 Connector, SMA Connector are the most popular connectors in the market. Connectors are used to join optical fibers where a connect/disconnect capability is required. The basic connector unit is a connector assembly. A connector assembly consists of an adapter and two connector plugs. Due to the sophisticated polishing and tuning procedures that may be incorporated into optical connector manufacturing, connectors are generally assembled onto optical fiber in a supplier’s manufacturing facility.
Application
Single mode fiber with a relatively narrow diameter, through which only one mode will propagate typically 1310 or 1550nm, which is used in many applications where data is sent at multi frequency (WDM Wave-Division-Multiplexing). Today’s telephone companies use single mode fiber throughout their system as the backbone architecture and as the long-distance connection between city phone systems. Local Area Networks (LAN) is a collective group of computers, or computer systems, connected to each other allowing for shared program software or data bases. Colleges, universities, office buildings, and industrial plants, just to name a few, all make use of single mode fiber within their LAN systems. Power companies are an emerging group that have begun to utilize fiber optics in their communication systems. Most power utilities already have single fiber optic communication systems in use for monitoring their power grid systems. At last, I hope this passage might be useful for the readers to have a brief understanding of SMF.
What Does a SFP Mean?
A small form-factor pluggable (SFP) transceiver is a compact, hot-swappable, input/output transceiver used in data communication and telecommunications networks. SFP interfaces between communication devices like switches, routers and fiber optic cables, and performs conversions between optical and electrical signals. SFP is also called a mini gigabit interface converter (GBIC) because its function is similar to the GBIC transceiver but with much smaller dimensions. The SFP transceiver is not standardized by any official standards body, but rather is specified by a multi-source agreement (MSA), which was developed and is followed by different transceiver manufacturers.
Types of SFP Transceivers
SFP Transceivers have a wide range of detachable interfaces to multimode/single-mode fiber optics, which allows users to select the appropriate transceiver according to the required optical range for the network. Besides, SFP transceivers are also available with copper cable interfaces, which allows a host device designed primarily for optical fiber communications to also communicate over unshielded twisted pair networking cables. Available optical SFP modules are generally divided into the following categories: 850 nm/550 m from the MMF (SX), 1310 nm/10 km from the SMF (LX), 1550 nm/80 km from the ZX and DWDM.
Applications of SFP Transceivers
SFP transceivers support communications standards including synchronous optical networking (SONET)/synchronous digital hierarchy (SDH), gigabit ethernet and fiber channel. They also allow the transport of fast Ethernet and gigabit Ethernet LAN packets over time-division-multiplexing-based WANs, as well as the transmission of E1/T1 streams over packet-switched networks. SFP sockets are found in Ethernet switches, routers, firewalls and network interface cards. Storage interface cards, also called HBAs or Fibre Channel storage switches, also make use of these modules, supporting different speeds such as 2Gb, 4Gb, and 8Gb. Because of their low cost, low profile, and ability to provide a connection to different types of optical fiber, SFP provides such equipment with enhanced flexibility.
Advantages of SFP Transceivers
SFP transceiver is pluggable that makes it easy to alter the optical interface in the last step of card manufacturing. It’s also easy to accommodate different connector interfaces. Modern optical SFP transceivers support digital diagnostics monitoring (DDM) functions, also known as digital optical monitoring (DOM). This feature gives users the ability to monitor the real-time parameters of SFP, such as optical output power, optical input power, temperature, laser-bias current and transceiver supply voltage. SFP transceivers also have a higher optical reliability and will permit higher soldering temperatures. SFP transceivers are recommended by fiber optic component providers to ensure proper data transmission.
