Defined by the Electronic Industries Association and Telecommunications Industry Association (commonly known as EIA/TIA), CAT5 (Category 5) cable is the copper wiring using twisted pair technology, designed for Ethernet networks. The term "Category” refers to the classifications of UTP (unshielded twisted pair) cables. Since its inception in the 1990s, CAT5 has become one of the most popular types of of all twisted pair cable types which include CAT3, CAT4, CAT5, CAT6, etc. This article details CAT5 used in copper networks from its working principles, its standard, as well as its installation considerations.

CAT5 is widely used in 100BASE-TX and 1000BASE-T Ethernet networks. CAT5 typically contains four pairs of copper wire. In 100BASE-TX standard, the signals are transmitted across only two of the CAT5 pairs. One pair is used to transmit signals, and the second pair receives the signals, leaving the other two unused in signal transmission. What’s more, the 100BASE-TX signals only run in one direction across the pairs. As technology advanced, the 1000BASE-T Gigabit Ethernet (GbE) standard was developed. 1000BASE-T standard utilizes all four copper pairs to transmit up to 250 megabits of data per second (Mbps) in full duplex transmission across each pair. That is to say, each pair is able to transmit and receive signals simultaneously. 1000BASE-T modules (eg. GLC-T) functioning over CAT 5 with RJ-45 connector achieve full duplex transmission with link length up to 100m (328ft).

There are two standards for CAT5 wiring, EIA/TIA-568A and EIA/TIA-568B. The following passages mainly discuss EIA/TIA-568A.

The TIA-EIA-568-A standard defined the following three main parameters for testing Category 5 cabling installations: wiremap, attenuation, and Near End Crosstalk (NEXT).

Wiremap is a continuity test. It assures that the conductors that make up the four twisted pairs in the cable are continuous from the termination point of one end of the link to the other. This test assures that the conductors are terminated correctly at each end and that none of the conductor pairs are crossed or short-circuited.

Attenuation is the loss of signal, as it is transmitted from the end of the cable to the opposite end at which it is received. Attenuation, also referred to as Insertion Loss, is measured in decibels (dB). For attenuation, the lower the dB value is, the better the performance is, and of course less signal is lost. This attenuation is typically caused by absorption, reflection, diffusion, scattering, deflection.

Near End Crosstalk (NEXT) measures the amount of signal coupled from one pair to another within the cable caused by radiation emission at the transmitting end.If the crosstalk is great enough, it will interfere with signals received across the circuit. Crosstalk is measured in dB. The higher the dB value, the better the performance, more of the signal is transmitted and less is lost due to coupling.

After testing parameters are mentioned above, here goes the notes of CAT 5 installation.

• Never pull CAT5 copper wire with excessive force. The CAT5 tension limitation is 25 lbs, much lower than standard audio/video cable.

• Never step on, crush, or crimp CAT5.

• Avoid periodic sags; vary the intervals if the cable must sag.

• Do not bend CAT5 wire tightly around a corner; ensure that it bends gradually, so that a whole circle would be at least two inches in diameter.

• Do not allow knots or kinks, even temporarily.

• Never run CAT5 parallel to power wiring closer than six inches.

• Avoid splices. Every splice degrades the line.

Although CAT5 is superseded by CAT5e in many applications, most CAT5 cable meets Cat5e standards and it’s still a commonplace in Local Area Networks (LANs). Many copper networks choose CAT5 as their transmission media because of its low price and high performance. Fiberstore supplies many CAT5 RJ45 pluggable modules, like 100BASE-TX, and 1000BASE-T transceivers (eg. SFP-GE-T). For more information about copper network solutions, you can visit Fiberstore.

Originaly published at www.fiber-optic-components.com/cat5-copper-network-solutions-choice.html

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Owing to its ubiquity, simplicity and low cost, Ethernet, one technology enabling Internet communications, is everywhere, from carrier networks to local area networks, from desktop PCs to the largest supercomputers. And with its widespread deployment, there occurs countless equipment accordingly designed for Gigabit communications, such as SFP+ transceiver. Are you familiar with SFP+? How much do you know about its testing challenges? This text will discuss some key features of SFP+ firstly, and then delve into its testing challenges.

As an enhanced version of the small form-factor pluggable (SFP), the enhanced SFP (SFP+) is a hot-pluggable, small-footprint, and multi-rate optical transceiver accessible for up to 16 Gbit/s data communications and storage-area network (SAN) applications. And this SFP+ enjoys the following advantages.

Just as the last paragraph mentioned above, the SFP+ module is a variant of the SFP optical transceiver. It simplifies the functionality of the 10G optical module significantly by moving functions, such as clock and data recovery (CDR), electronic dispersion compensation (EDC), 10G SERDES, and signal conditioning. Thus, the SFP+ module requires fewer components, consumes less power, and allows for increased port density. Certainly, it’s also smaller and less expensive compared with the 10-Gigabit small form-factor pluggable module (XFP) form factor.

As SFP+ becomes more prevalent, it’s imperative for engineers to become familiar with some of the key challenges linked to testing SFP+ capable devices.

On one hand, SFP+ gives a hand in reducing the overall system cost. On the other, its physical layer (PHY) and performance are put with new burdens. The SERDES framer interface (SFI) between the host board and the SFP+ module displays great design and testing challenges.

• One challenge attributes to the increased port density and the testing time required for 48 or more ports per rack. For instance, there are 15 measurements each for the host transmitter tests, and each of these measurements using manual methods can easily take from three to five minutes. This means it will take engineers more than an hour per port to complete the required tests.

• The second one that engineers need to consider is: if a measurement fails, how can they determine which component is causing such a failure, and how they debug the issue to arrive at the root cause. Such determinations are especially challenging because of the tight physical packaging and compact designs.

• Another challenge falls on the connectivity. That is: how to get the signal out from the device under test (DUT) to an oscilloscope. Test fixtures are typically required, but questions arise around consequently: whether the fixtures have been tested and validated against the specification.

• The additional problem lies in the fact that the SFP+ specification requires some measurements to be performed using a PRBS31 signal. At a sampling rate of 50 Gsamples/s, the designer can acquire around 40 million unit intervals (UIs). At a sampling rate of 100 Gsamples/s, the instrument can acquire 20 million UIs. However, a PRBS31 pattern has more than 2 billion UIs. Hence, acquiring an entire pattern poses a challenge.

SFP+ transceiver with its compact size has become a popular industry format supported by many network component vendors. And with the above-mentioned points in mind, designers have gained an overview of SFP+ transceiver testing challenges. Fiberstore is an outstanding and professional SFP+ manufacturer and supplier, available with a sea of high-performance and -quality SFP+ transceivers. Besides SFP+transceiver, Fiberstore also supplies QSFP+ transceiver, fully compatible with major brands. For more information about transceivers, you can visit Fiberstore.

Originally published at www.fiber-optic-components.com/sfp-transceiver-do-you-know-its-testing-challenges.html

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The advancements of cable-based technologies have made wider accessibility to greater bandwidth possible in Local Area Network (LAN). With so many network options, to select a right cable-based solution for broadband connection services is a little confusing. When such factors as cost, speed, bandwidth and immunity are considered, which one is an ideal choice for networks, coaxial cable or twisted pair cable? Or is the fiber optic cable that meets your needs?

Coaxial cable, or in a foam insulation, symmetrically surrounded by a woven braided metal shield, then covered in a plastic jacket. Because of its insulating property, coaxial cable can carry analogy signals with a wide range of frequencies. Thus it is widely used in feedlines connecting radio transmitters and receivers with their antennas, computer network connections, digital audio, and distributing cable television signals. The following figure shows the structure of coaxial cable.

Actually, there exists another cable, twin-ax cable, which is similar to coaxial cable, but with two inner conductors instead of one. This kind of cable comes in either an active or passive twin-ax (twin-axial) cable assembly, used for 10, 40 or 100 Gigabit Ethernet (GbE) links.Like QSFP-H40G-CU1M, this Cisco 40G cabling product is the QSFP to QSFP passive copper cable assembly designed for high-performance 40GbE networks.

Twisted pair cable is a type of wiring in which two conductors of a single circuit are twisted together. It comes in two versions: Shielded Twisted Pair (STP) and Unshielded Twisted Pair (UTP). STP is commonly used in Token Ring networks and UTP is in Ethernet networks. The image below displays what UTP (left) and STP (right) look like.

A fiber optic cable is a cable containing one or more optical fibers. Fiber optic cables often contain several silica cores, and each fiber can accommodate many wavelengths (or channels), allowing fiber to accommodate ever-increasing data capacity requirements. When terminated with LC/SC/ST/FC/MTRJ/MU/SMA connectors on both ends, such as LC-LC, LC-SC, LC-ST, SC-ST, SC-SC, ST-ST etc, fiber optic cables can achieve fiber link connection between equipment.

Coaxial cable can be installed easily, relatively resistant to interference. However, it is bulky and just ideal for short length because of its high attenuation. It would be expensive over long-distance data transmission. By contrast, twisted pair cable is the most flexible and cheapest among three kinds of cables, easy to install and operate. But it also encounters attenuation problem and offers relatively low bandwidth. In addition, it is susceptible to interference and noises. As one of the most popular mediums for both new cabling installations and upgrades, including backbone, horizontal, and even desktop applications, fiber optic cable is small in size and light in weight. Because the conductor is glass which means that no electricity can flow through, fiber cable is immune to electromagnetic interference. The biggest advantage of fiber optic cable is that it can transmit a big amount of data with low loss at high speed over long distance. Nevertheless, it needs complicated installing skills, difficult to work with and expensive in the short run.

When selecting which kind of cable is appropriate for network services, one should keep in mind that each cable has its unique advantages and disadvantages concerning about these factors: cost, speed, security, reliability, bandwidth, data carrying-capacity, and so on.

Choosing among coaxial cable, twin-ax cable, twisted pair cable and fiber optic cable depends on your needs. You can balance the cost and the requirements of bandwidth to make a choice. In Fiberstore, you can find twisted pair cables and a series of fiber optic cables. Other cables, such as active optical cable (AOC) (eg. QSFP-4X10G-AOC10M) are also available for your networks. You can visit Fiberstore for more information about cable-based solutions.

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The increased deployment of 10 Gigabit Ethernet (GbE) infrastructure, coupled with the growing applications of bandwidth-demanding network services, drives the need for dense 40GbE switching. High-density 40G switches, such as Arista QSFP-40G Universal transceivers, are the available ports enabling the easy 10G to 40G migration. How much do you know about this Arista QSFP-40G Universal transceiver? This text will guide you to delve into this 40G QSFP+ transceiver.

The Arista QSFP-40G Universal transceiver is a pluggable optical transceiver in an industry standard QSFP+ form factor that can operate with both duplex multi-mode fiber (MMF) and single-mode fiber (SMF). It has four channels of 10G multiplexed inside the module, giving an aggregated 40G bandwidth over 2 strands of fibers. It’s called Universal owing to its ability to communicate with both MMF and SMF without the need for any software/hardware changes to the module or any additional hardware in the network. Here is a picture of Arista QSFP-40G Universal transceiver listed on Fiberstore.

The Arista QSFP-40G Universal transceiver uses a duplex LC connector, and operates on a wide range of fiber optic cables, including OM3 and OM4 MMF and SMF, realizing 150m reach on OM3 and OM4, 500m on SMF. It’s defined to the IEEE 40GBASE-LR4 standard, interoperable with QSFP-40G-LR4 and QSFP-40G-LR4L for distances up to 500m, compliant to the QSFP+ MSA SFF-8436 which defines the specification for QSFP optics. When migrating from 10G to 40G, the existing fiber patch cords, panels, trunks and cabling systems can be used without requiring a redesign or expansion of the fiber network, thus avoiding adding cost or complexity to the migration.

Arista QSFP-40G Universal transceiver addresses several challenges met in data center, and it boasts of the following advantages.

Since the existing multi-mode 40GbE solutions need the use of 8 fibers for a 40G link, users have to add additional fibers to increase the number of 40G links with other 40G QSFP+ optics. But by utilizing Arista QSFP-40G Universal transceiver, users increase the number of 40G links by 4X without making any changes to their fiber infrastructure. More specifically, with the Arista QSFP-40G Universal transceiver for the same number of 40G links as 10G links, there is no need to change fiber termination, nor to upgrade patch panels or trunks, but still the network scale and performance are expanded.

Besides, Arista QSFP-40G Universal transceiver is designed for both MMF and SMF, leading to simplified operations. Its interoperability with IEEE 40GBASE-LR4 and 40G-LRL4 allows easy connection to third party routers and switches in existing networks. Take JG661A for example, this HP product is exactly a 40GBASE-LR4 QSFP+ transceiver designed to run over SMF with duplex LC connector.

Additionally, this kind of 40G QSFP+ transceiver supports Digital Optical Monitoring (DOM) for link quality monitoring. DOM provides access to real-time operating parameters of the transceiver through a digital interface. It enables pro-active monitoring of the key parameters of the transceiver, helping network operators to become aware of degrading fiber paths, to detect transceiver problems and to test splicing/patching work remotely and in a non-intrusive way.

Arista QSFP-40G Universal transceiver offers a very cost-effective connectivity solution for data centers to migrate from 10 Gigabits/s to 40Gigabits/s with minimal disruption within existing multi-mode or single-mode infrastructure. As an excellent fiber optics products manufacturer and supplier, as well as a third party, Fiberstore supplies many Arista QSFP-40G-UNIV transceivers which are 100% compatible the original Arista QSFP-40G Universal transceivers. In addition, Fiberstore also offers 40G QSFP+ transceivers compatible with other major brands, including Cisco, Juniper and HP (eg. HP QSFP+). For more information about 40G QSFP+ transceivers, you can visit Fiberstore.

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Single-mode fiber (SMF) cables support advanced network applications required in data centers, enabling guaranteed performance for Gigabit applications. SMF can be categorized into OS1 and OS2. That is, OS1 and OS2 are cabled SMF specifications. For many people, one of the confusing aspects in fiber optics industry may contribute to the standardization, since several standards may be specified under one fiber cable type, just as SMF. Actually, the differences between OS1 and OS2 specifications are a little obvious. This text will explain the differences between OS1 and OS2.

The table listed below is about OS1 and OS2 specification differences.

First introduced in the year 2002, OS1 refers to a very old specification for SMF. The mechanical, optical and environmental characteristics of OS1 are compliant with ITU-T G.652A or ITU-T G.652B (IEC 60793-2-50 Type B1.1). Additionally, the low water peak fibers categorized in ITU-T recommendations as G.652C and G.652D also come under OS1 fibers. To put it simply, OS1 is a general term used to specify SMF that comes under the ITU-T G.652. Or in another way, OS1 covers all the SMFs that comply with ITU-T G.652 characteristics. In contrast, OS2 was introduced in the year 2006. Only G.652C and G.652D come under OS2, meaning that OS2 SMFs are low water peak fibers only.

OS1 is tight-buffered cable construction, appropriate for indoor applications, such as campus or data centers. On the contrary, OS2 is loose-tube cable construction, suitable for outdoor applications, including street or underground.

OS1 or OS2 fiber optical performance is discussed mainly from their attenuation and transmission distance. As for OS1 operating between 1310 nm and 1550 nm, its maximum attenuation allowed per km for an installed cable is 1.0 db, with the maximum transmission distance reaching 2 km at 10 Gigabit Ethernet (GbE) transmission. When concerning about OS2, maximum attenuation allowed per kilometer is 0.4db between 1310 nm and 1550 nm, allowing the maximum transmission distance of 10 km at 10GbE. As far as 40GbE transmission is concerned, the maximum distance of SMF is 40 km. For example, QSFP-40G-ER4, a Cisco 40GBASE-ER4 transceiver, takes SMF as its transmission medium for 40G links. The image below shows this Cisco QSFP-40G-ER4 module listed on Fiberstore.

OS2 SMFs can’t be connected with OS1 SMFs. If they are connected, unpredicted signal performance at water peak region would occur. So, it you want to use SMFs for your indoor applications, then choose OS1. For outdoor cases, OS2 is optimized. Besides, when the required transmission distance is less than 2 km, it’s wise to choose OS1 SMF, since OS1 is able to meet this requirement while costing less than OS2 SMF.

According to what have been discussed above, the confusion between these OS1 and OS2 specifications has been cleared off. Fiberstore offers various fiber optical products, including these OS1 and OS2 SMFs of high quality. In addition, Fiberstore also supplies fiber optic transceivers which are fully compatible with some major brands, such as Brocade QSFP+. You can visit Fiberstore for more information about OS1 and OS2 SMFs as well as the related fiber optic transceivers.

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