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Black Box Explains...How to maximize your wireless range.

There are four simple rules that enable you to transmit wireless communications up to their maximum range:
• Try to keep a direct line between the transmitter and receiver.
• Minimize... more/see it nowthe number of walls and ceilings between the transmitter and receiver. Such obstructions reduce the range.
• If there are obstructions, be sure the wireless signal passes through drywall or open doorways and not other materials.
• Keep the transmitter and receiver at least 3 to 6 feet (0.9 to 1.8 m) away from electrical devices or appliances, especially those that generate extreme RF noise. collapse


Black Box Explains…Fiber Ethernet adapters vs. media converters.

When running fiber to the desktop, you have two choices for making the connection from the fiber to a PC: a fiber Ethernet adapter or a media converter like our... more/see it nowMicro Mini Media Converter.

Fiber Ethernet adapters:

  • Less expensive.
  • Create no desktop clutter, but the PC must be opened.
  • Powered from the PC—require no separate power provision.
  • Require an open PCI or PCI-E slot in the PC.
  • Can create driver issues that must be resolved.
  • May be required in high-security installations that require a 100% fiber link to the desktop.

  • Media converters:
  • More expensive.
  • No need to open the PC but can create a cluttered look.
  • Powered from an AC outlet or a PC’s USB port.
  • Don’t require an open slot in the PC.
  • Plug-and-play installation—totally transparent to data, so there are no driver problems; install in seconds.
  • The short copper link from media converter to PC may be a security vulnerability.
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    Black Box Explains...vDSL.

    VDSL (Very High Bit-Rate Digital Subscriber Line or Very High-Speed Digital Subscriber Line) is a “last-mile” broadband solution for both businesses and homes, providing economical, high-speed connections to fiber optic... more/see it nowbackbones.

    VDSL enables the simultaneous transmission of voice, data, and video on existing voice-grade copper wires. Depending on the intended applications, you can set VDSL to run symmetrically or asymmetrically. VDSL’s high bandwidth allows for applications such as high-definition television, video-on-demand (VOD), high-quality videoconferencing, medical imaging, fast Internet access, and regular voice telephone services—all over a single voice-grade twisted pair. The actual VDSL distances you achieve vary based on line rate, gauge and type of wire, and noise/crosstalk environment. collapse


    Black Box Explains…Media converters that also work as switches.

    Media converters transparently convert the incoming electrical signal from one cable type and then transmit it over another type—thick coax to Thin, UTP to fiber, and so on. Traditionally, media... more/see it nowconverters were purely Layer 1 devices that only converted electrical signals and physical media and didn’t do anything to the data coming through the link.

    Today’s media converters, however, are often more advanced Layer 2 Ethernet devices that, like traditional media converters, provide Layer 1 electrical and physical conversion. But, unlike traditional media converters, they also provide Layer 2 services and route Ethernet packets based on MAC address. These media converters are often called media converter switches, switching media converters, or Layer 2 media converters. They enable you to have multiple connections rather than just one simple in-and-out connection. And because they’re switches, they increase network efficiency.

    Media converters are often used to connect newer 100-Mbps, Gigabit Ethernet, or ATM equipment to existing networks, which are generally 10BASE-T, 100BASE-T, or a mixture of both. They can also be used in pairs to insert a fiber segment into copper networks to increase cabling distances and enhance immunity to electromagnetic interference.

    Rent an apartment…
    Media converters are available in standalone models that convert between two different media types and in chassis-based models that house many media converters in a a single chassis.

    Standalone models convert between two media. But, like a small apartment, they can be outgrown.

    Consider your current and future applications before selecting a media converter. A good way to anticipate future network requirements is to choose media converters that work as standalone devices but can be rackmounted if needed later.

    …or buy a house.
    Chassis-based or modular media converter systems are normally rackmountable and have slots to house media converter modules. Like a well-planned house, the chassis gives you room to grow. These are used when many Ethernet segments of different media types need to be connected in a central location. Modules are available for the same conversions performed by the standalone converters, and they enable you to mix different media types such as 10BASE-T, 100BASE-TX, 100BASE-FX, ATM, and Gigabit modules. Although enterprise-level chassis-based systems generally have modules that can only be used in a chassis, many midrange systems feature modules that can be used individually or in a chassis. collapse


    Black Box Explains...Media converters.



    Media converters interconnect different cable types such as twisted pair, fiber, and coax within an existing network. They are often used to connect newer Ethernet equipment to legacy cabling.... more/see it nowThey can also be used in pairs to insert a fiber segment into copper networks to increase cabling distances and enhance immunity to electromagnetic interference (EMI).


    Traditional media converters are purely Layer 1 devices that only convert electrical signals and physical media. They don’t do anything to the data coming through the link so they’re totally transparent to data. These converters have two ports—one port for each media type. Layer 1 media converters only operate at one speed and cannot, for instance, support both 10-Mbps and 100-Mbps Ethernet.


    Some media converters are more advanced Layer 2 Ethernet devices that, like traditional media converters, provide Layer 1 electrical and physical conversion. But, unlike traditional media converters, they also provide Layer 2 services—in other words, they’re really switches. This kind of media converter often has more than two ports, enabling you to, for instance, extend two or more copper links across a single fiber link. They also often feature autosensing ports on the copper side, making them useful for linking segments operating at different speeds.


    Media converters are available in standalone models that convert between two different media types and in chassis-based models that connect many different media types in a single housing.




    Rent an apartment

    Standalone converters convert between two media. But, like a small apartment, they can be outgrown. Consider your current and future applications before selecting a media converter. Standalone converters are available in many configurations, including 10BASE-T to multimode or single-mode fiber, 10BASE-T to Thin coax (ThinNet), 10BASE-T to thick coax (standard Ethernet), CDDI to FDDI, and Thin coax to fiber. 100BASE-T and 100BASE-FX models that connect UTP to single- or multimode fiber are also available. With the development of Gigabit Ethernet (1000 Mbps), media converters have been created to make the transition to high-speed networks easier.




    ...or buy a house.

    Chassis-based or modular media converters are normally rackmountable and have slots that house media converter modules. Like a well-planned house, the chassis gives you room to grow. These are used when many Ethernet segments of different media types need to be connected in a central location. Modules are available for the same conversions performed by the standalone converters, and 10BASE-T, 100BASE-TX, 100BASE-FX, and Gigabit modules may also be mixed.

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    Black Box Explains...Layer 2, 3, and 4 switches.



    ...more/see it now
    OSI Layer Physical
    Component
    7-Application Applicaton Software

    LAN-Compatible Software
    E-Mail, Diagnostics, Word Processing, Database


    Network Applications
    6-Presentation Data-
    Conversion Utilities
    Vendor-Specific Network Shells and Gateway™ Workstation Software
    5-Session Network Operating System SPX NetBIOS DECnet™ TCP/IP AppleTalk®
    4-Transport Novell® NetWare® IPX™ PC LAN LAN Mgr DECnet PC/TCP® VINES™ NFS TOPS® Apple
    Share®
    3-Network Control
    2-Data Link Network E A TR P TR E TR E E E P E P
    1-Physical E=Ethernet; TR=Token Ring; A=ARCNET®; P=PhoneNET®

    With the rapid development of computer networks over the last decade, high-end switching has become one of the most important functions on a network for moving data efficiently and quickly from one place to another.


    Here’s how a switch works: As data passes through the switch, it examines addressing information attached to each data packet. From this information, the switch determines the packet’s destination on the network. It then creates a virtual link to the destination and sends the packet there.


    The efficiency and speed of a switch depends on its algorithms, its switching fabric, and its processor. Its complexity is determined by the layer at which the switch operates in the OSI (Open Systems Interconnection) Reference Model (see above).


    OSI is a layered network design framework that establishes a standard so that devices from different vendors work together. Network addresses are based on this OSI Model and are hierarchical. The more details that are included, the more specific the address becomes and the easier it is to find.


    The Layer at which the switch operates is determined by how much addressing detail the switch reads as data passes through.


    Switches can also be considered low end or high end. A low-end switch operates in Layer 2 of the OSI Model and can also operate in a combination of Layers 2 and 3. High-end switches operate in Layer 3, Layer 4, or a combination of the two.


    Layer 2 Switches (The Data-Link Layer)

    Layer 2 switches operate using physical network addresses. Physical addresses, also known as link-layer, hardware, or MAC-layer addresses, identify individual devices. Most hardware devices are permanently assigned this number during the manufacturing process.


    Switches operating at Layer 2 are very fast because they’re just sorting physical addresses, but they usually aren’t very smart—that is, they don’t look at the data packet very closely to learn anything more about where it’s headed.


    Layer 3 Switches (The Network Layer)

    Layer 3 switches use network or IP addresses that identify locations on the network. They read network addresses more closely than Layer 2 switches—they identify network locations as well as the physical device. A location can be a LAN workstation, a location in a computer’s memory, or even a different packet of data traveling through a network.


    Switches operating at Layer 3 are smarter than Layer 2 devices and incorporate routing functions to actively calculate the best way to send a packet to its destination. But although they’re smarter, they may not be as fast if their algorithms, fabric, and processor don’t support high speeds.


    Layer 4 Switches (The Transport Layer)

    Layer 4 of the OSI Model coordinates communications between systems. Layer 4 switches are capable of identifying which application protocols (HTTP, SNTP, FTP, and so forth) are included with each packet, and they use this information to hand off the packet to the appropriate higher-layer software. Layer 4 switches make packet-forwarding decisions based not only on the MAC address and IP address, but also on the application to which a packet belongs.


    Because Layer 4 devices enable you to establish priorities for network traffic based on application, you can assign a high priority to packets belonging to vital in-house applications such as Peoplesoft, with different forwarding rules for low-priority packets such as generic HTTP-based Internet traffic.


    Layer 4 switches also provide an effective wire-speed security shield for your network because any company- or industry-specific protocols can be confined to only authorized switched ports or users. This security feature is often reinforced with traffic filtering and forwarding features.

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    Black Box Explains...SFP, SFP+, and XFP transceivers.

    SFP, SFP+, and XFP are all terms for a type of transceiver that plugs into a special port on a switch or other network device to convert the port to... more/see it nowa copper or fiber interface. These compact transceivers replace the older, bulkier GBIC interface. Although these devices are available in copper, their most common use is to add fiber ports. Fiber options include multimode and single-mode fiber in a variety of wavelengths covering distances of up to 120 kilometers (about 75 miles), as well as WDM fiber, which uses two separate wavelengths to both send and receive data on a single fiber strand.

    SFPs support speeds up to 4.25 Gbps and are generally used for Fast Ethernet or Gigabit Ethernet applications. The expanded SFP standard, SFP+, supports speeds of 10 Gbps or higher over fiber. XFP is a separate standard that also supports 10-Gbps speeds. The primary difference between SFP+ and the slightly older XFP standard is that SFP+ moves the chip for clock and data recovery into a line card on the host device. This makes an SFP+ smaller than an XFP, enabling greater port density.

    Because all these compact transcievers are hot-swappable, there’s no need to shut down a switch to swap out a module—it’s easy to change interfaces on the fly for upgrades and maintenance.

    Another characteristic shared by this group of transcievers is that they’re OSI Layer 1 devices—they’re transparent to data and do not examine or alter data in any way. Although they’re primarily used with Ethernet, they’re also compatible with uncommon or legacy standards such as Fibre Channel, ATM, SONET, or Token Ring.

    Formats for SFP, SFP+, and XFP transceivers have been standardized by multisource agreements (MSAs) between manufacturers, so physical dimensions, connectors, and signaling are consistent and interchangeable. Be aware though that some major manufacturers, notably Cisco, sell network devices with slots that lock out transceivers from other vendors. collapse


    Black Box Explains...Choosing a wireless antenna.


    Ride the wave.

    One of the most critical components to operating a successful wireless network is having the right antennas. Antennas come in many different shapes and sizes,... more/see it noweach designed for a specific function. Selecting the right antennas for your network is crucial to achieving optimum network performance. In addition, using the right antennas can decrease your networking costs since you’ll need fewer antennas and access points.


    Basically, a wireless network consists of data, voice, and video information packets being transmitted over low-frequency radio waves instead of electrically over copper cable or via light over fiber lines. The antenna acts as a radiator and transmits waves through the air, just like radio and TV stations. Antennas also receive the waves from the air and transport them to the receiver, which is a radio, TV, or in the case of wireless networking, a router or an access point.


    Type cast.

    The type of antennas you use depends on what type of network you’re setting up and the coverage you need. How large is your network? Is it for a home, single office, campus, or larger? Is it point-to-point or multipoint?


    The physical design-walls, floors, etc.- of the building(s) you’re working in also affects the type and number of antennas you need. In addition, physical terrain affects your antenna choices. Obviously, a clear line of sight works best, but you need to consider obstructions such as trees, buildings, hills, and water. (Radio waves travel faster over land than water.) You even need to consider traffic noise in urban settings.


    The ideal shape.

    Let’s take a look at the different types of antennas.


    Isotropic Antenna. First, think of the introduction to the old RKO movies. A huge tower sits on top of the world and emanates circular waves in all directions. If you could actually see the waves, they would form a perfect sphere around the tower. This type of antenna is called an isotropic antenna, and does not exist in the real world. It is theoretical and is used as a base point for measuring actual antennas.


    Go in the right direction.

    Now let’s turn to real-world antennas. There are many types of antennas that emit radio waves in different directions, shapes, and on different planes. Think of the spherical isotropic antenna. If squeezed from the sides, it will become shaped like a wheel and will concentrate waves on a vertical plane. If squeezed from the top, it will flatten out like a pancake and radiate waves on a horizontal plane. Thus, there are two basic types of antennas: directional and omnidirectional.


    Directional antennas.

    Directional antennas, primarily used in point-to-point networks, concentrate the waves in one direction much like a flashlight concentrates light in a narrow beam. Directional antennas include backfire, Yagi, dish, panel, and sector.


    Backfire. This small directional antenna looks like a cake pan with a tin can in the middle. It’s designed to be compact, often under 11" in diameter, making it unobtrusive and practical for outdoor use. These antennas also offer excellent gain, and can be used in both point-to-point or point-to-multipoint systems.


    Yagi. The Yagi-Uda (or Yagi) antenna is named for its Japanese inventors. The antenna was originally intended for radio use and is now frequently used in 802.11 wireless systems.


    A Yagi antenna is highly directional. It looks like a long fishbone with a central spine and perpendicular rods or discs at specified intervals. Yagi antennas offer superior gain and highly vertical directionality. The longer the Yagi, the more focused its radiation is. Many outdoor Yagi antennas are covered in PVC so you can’t see the inner structure.


    Yagi antennas are good for making point-to-point links in long narrow areas (for instance, connecting to a distant point in a valley) or for point-to-point links between buildings. They can also be used to extend the range of a point-to-multipoint network.


    Parabolic or Dish. These antennas look like a circular or rectangular concave bowl or "dish". The backboard can be solid or a grid design. Parabolic grid designs are excellent for outdoor use since the wind blows right through them. The concave nature of this dish design focuses energy into a narrow beam that can travel long distances, even up to several miles. This makes parabolic antennas ideal for point-to-point network connections. Since they generate a narrow beam in both the horizontal and vertical planes, offer excellent gain, and minimize interference, they’re ideal for long-distance point-to-point networks.


    Panel or Patch. These antennas are often square or rectangular, and they’re frequently hung on walls. They’re designed to radiate horizontally forward and to the side, but not behind them. Sometimes they’re called "picture-frame" antennas.


    Panel antennas are ideal in applications where the access point is at one end of a building. They’re good for penetrating a single floor of a building, and for small and medium-size homes and offices. Since they might not have much vertical radiation, they might not be a good choice for multifloor applications.


    Because panel antennas can be easily concealed, they’re a good choice when aesthetics are important.


    Sector. A sector antenna can be any type of antenna that directs the radio waves in a specific area. They are often large, outdoor flat-panel or dish-type antennas mounted up high and tilted downward toward the ground. These antennas are often used in sprawling campus settings to cover large areas.


    Omnidirectional antennas.

    Omnidirectional antennas provide the widest coverage possible and are generally used in point-to-multipoint networks. Their range can be extended by overlapping circles of coverage from multiple access points. Most omnidirectional antennas emanate waves in a fan-shaped pattern on a horizontal plane. Overall, omnidirectional antennas have lower gain than directional antennas. Examples of omnidirectional antennas include: integrated, blade, and ceiling.


    Integrated. Integrated antennas are antennas that are built into wireless networking devices. They may be embedded in PC card client adapters or in the covers or body of laptops or other devices, such as access points. Integrated antennas often do not offer the same reception as external antennas and might not pick up weak signals. Access points with integral antennas must often be moved or tilted to get the best reception.


    Blade. These small, omnidirectional antennas are often housed in long, thin envelopes of plastic. They are most often used to pick up a signal in a low-signal or no-signal spot. You usually will see them on the walls of cubicles, mounted on desktops, or even hung above cubicles to catch signals. They’re basically an inexpensive signal booster.


    Ceiling Dome. These are sometimes also called ceiling blister antennas. They look somewhat like a smoke detector and are designed for unobtrusive use in ceilings, particularly drop ceilings. Ceiling dome antennas often have a pigtail for easy connection to access points. They’re excellent for use in corporate environments where wide coverage over a cube farm is needed.


    Wave basics.

    To better understand wireless antennas and networking, there are some basic measurements and terms that need to be discussed.


    Gain. One of the primary measurements of antennas is gain. Gain is measured as dBi, which is how much the antenna increases the transmitter’s power compared to the theoretical isotropic antenna, which has a gain of 0 dBi. dBi is the true gain the antenna provides to the transmitter’s output. Gain is also reciprocal-it’s the same transmitting and receiving. Higher gain means stronger sent and received signals. An easy way to remember gain basics is that every 3 dB of gain added doubles the effective power output of an antenna. The more an antenna concentrates a signal, the higher the gain it will have.


    You can actually calculate the gains and losses of a system by adding up the gains and losses of its parts in decibels.


    Frequency and Wavelength. Electromagnetic waves are comprised of two components: frequency and wavelength.


    Frequency is how many waves occur each second. Wavelength is the distance between one peak of a wave and the next peak. Lower frequencies have longer wavelengths; higher frequencies have shorter wavelengths. For example, the frequency of AM radio is 1 MHz with a wavelength of about 1000 feet. FM radios operate at a much higher frequency of 100 MHz and have a wavelength of about 100 feet.


    The two most common frequencies for wireless networking are 2.4-GHz and 5-GHz. Both are very high frequencies with very short wavelengths in the microwave band. The 2.4-GHz frequency has a wavelength of about 5 inches.


    Beamwidth. Consider an antenna to be like a flashlight or spotlight. It reflects and directs the light (or radio waves) in a particular direction. Beamwidth actually measures how energy is focused or concentrated.


    Polarization. This is the direction in which the antenna radiates wavelengths, either vertically, horizontally, or circularly. Vertical antennas have vertical polarization and are the most common. For optimum performance, it is important that the sending and receiving antennas have the same polarization.


    VSWR and Return Loss. Voltage Standing Wave Ratio (VSWR) measures how well the antenna is matched to the network at the operating frequency being used. It indicates how much of the received signal won’t reach either the transceiver or receiver. Return loss measures how well matched an antenna is to the network. Typical VSWR numbers are 1:1.2 or 1:1.5. A typical return loss number is 20.

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    Black Box Explains...10-Gigabit Ethernet.

    10-Gigabit Ethernet, sometimes called 10-GbE or 10 GigE, is the latest improvement on the Ethernet standard, ratified in 2003 for fiber as the 802.3ae standard, in 2004 for twinax cable... more/see it now as the 802.3ak standard, and in 2006 for UTP as the 802.3an standard.

    10-Gigabit Ethernet offers ten times the speed of Gigabit Ethernet. This extraordinary throughput plus compatibility with existing Ethernet standards has resulted in 10-Gigabit Ethernet quickly becoming the new standard for high-speed network backbones, largely supplanting older technologies such as ATM over SONET. 10-Gigabit Ethernet has even made inroads in the area of storage area networks (SAN) where Fibre Channel has long been the dominant standard. This new Ethernet standard offers a fast, simple, relatively inexpensive way to incorporate super high-speed links into your network.

    Because 10-Gigabit Ethernet is simply an extension of the existing Ethernet standards family, it’s a true Ethernet standard—it’s totally backwards compatible and retains full compatibility with 10-/100-/1000-Mbps Ethernet. It has no impact on existing Ethernet nodes, enabling you to seamlessly upgrade your network with straightforward upgrade paths and scalability.

    10-Gigabit Ethernet is less costly to install than older high-speed standards such as ATM. And not only is it relatively inexpensive to install, but the cost of network maintenance and management also stays low—10-Gigabit Ethernet can easily be managed by local network administrators.

    10-Gigabit Ethernet is also more efficient than other high-speed standards. Because it uses the same Ethernet frames as earlier Ethernet standards, it can be integrated into your network using switches rather than routers. Packets don’t need to be fragmented, reassembled, or translated for data to get through.

    Unlike earlier Ethernet standards, which operate in half- or full-duplex, 10-Gigabit Ethernet operates in full-duplex only, eliminating collisions and abandoning the CSMA/CD protocol used to negotiate half-duplex links. It maintains MAC frame compatibility with earlier Ethernet standards with 64- to 1518-byte frame lengths. The 10-Gigabit standard does not support jumbo frames, although there are proprietary methods for accommodating them.

    Fiber 10-Gigabit Ethernet standards
    There are two groups of physical-layer (PHY) 10-Gigabit Ethernet standards for fiber: LAN-PHY and WAN-PHY.

    LAN-PHY is the most common group of standards. It’s used for simple switch and router connections over privately owned fiber and uses a line rate of 10.3125 Gbps with 64B/66B encoding.

    The other group of 10-Gigabit Ethernet standards, WAN-PHY, is used with SONET/SDH interfaces for wide area networking across cities, states—even internationally.

    LAN-PHY
    10GBASE-SR (Short-Range) is a serial short-range fiber standard that operates over two multimode fibers. It has a range of 26 to 82 meters (85 to 269 ft.) over legacy 62.5-µm 850-nm fiber and up to 300 meters (984 ft.) over 50-µm 850-nm fiber.

    10GBASE-LR (Long-Range) is a serial long-range 10-Gbps Ethernet standard that operates at ranges of up to 25 kilometers (15.5 mi.) on two 1310-nm single-mode fibers.

    10GBASE-ER (Extended-Range) is similar to 10GBASE-LR but supports distances up to 40 kilometers (24.9 mi.) over two 1550-nm single-mode fibers.

    10GBASE-LX4 uses Coarse-Wavelength Division Multiplexing (CWDM) to achieve ranges of 300 meters (984 ft.) over two legacy 850-nm multimode fibers or up to 10 kilometers (6.2 mi.) over two 1310-nm single-mode fibers. This standard multiplexes four data streams over four different wavelengths in the range of 1300 nm. Each wavelength carries 3.125 Gbps to achieve 10-Gigabit speed.

    WAN-PHY
    In fiber-based Gigabit Ethernet, the 10GBASE-SR, 10GBASE-LR, and 10GBASE-ER LAN-PHY standards have WAN-PHY equivalents called 10GBASE-SW, 10GBASE-LW, and 10GBASE-EW. There is no WAN-PHY standard corresponding to 10GBASE-LX4.

    WAN-PHY standards are designed to operate across high-speed systems such as SONET and SDH. These systems are often telco operated and can be used to provide high-speed data delivery worldwide. WAN-PHY 10-Gigabit Ethernet operates within SDH and SONET using an SDH/SONET frame running at 9.953 Gbps without the need to directly map Ethernet frames into SDH/SONET.

    WAN-PHY is transparent to data—from the user’s perspective it looks exactly the same as LAN-PHY.

    10-Gigabit Ethernet over Copper
    10GBASE-CX4
    10GBASE-CX4 is a standard that enables Ethernet to run over CX4 cable, which consists of four twinaxial copper pairs bundled into a single cable. CX4 cable is also used in high-speed InfiniBand® and Fibre Channel storage applications. Although CX4 cable is somewhat less expensive to install than fiber optic cable, it’s limited to distances of up to 15 meters. Because this standard uses such a specialized cable at short distances, 10GBASE-CX4 is generally used only in limited data center applications such as connecting servers or switches.

    10GBASE-Kx
    10GBASE-Kx is backplane 10-Gigabit Ethernet and consists of two standards. 10GBASE-KR is a serial standard compatible with 10GBASE-SR, 10GBASE-LR, and 10GBASE-ER. 10GBASE-KX4 is compatible with 10GBASE-LX4. These standards use up to 40 inches of copper printed circuit board with two connectors in place of cable. These very specialized standards are used primarily for switches, routers, and blade servers in data center applications.

    10GBASE-T
    10GBASE-T is the 10-Gigabit standard that uses the familiar shielded or unshielded copper UTP cable. It operates at distances of up to 55 meters (180 ft.) over existing Category 6 cabling or up to 100 meters (328 ft.) over augmented Category 6, or “6a,” cable, which is specially designed to reduce crosstalk between UTP cables. Category 6a cable is somewhat bulkier than Category 6 cable but retains the familiar RJ-45 connectors.

    To send data at these extremely high speeds across four-pair UTP cable, 10GBASE-T uses sophisticated digital signal processing to suppress crosstalk between pairs and to remove signal reflections.

    10-Gigabit Ethernet Applications
    > 10-Gigabit Ethernet is already being deployed in applications requiring extremely high bandwidth:
    > As a lower-cost alternative to Fibre Channel in storage area networking (SAN) applications.
    > High-speed server interconnects in server clusters.
    > Aggregation of Gigabit segments into 10-Gigabit Ethernet trunk lines.
    > High-speed switch-to-switch links in data centers.
    > Extremely long-distance Ethernet links over public SONET infrastructure.

    Although 10-Gigabit Ethernet is currently being implemented only by extremely high-volume users such as enterprise networks, universities, telecommunications carriers, and Internet service providers, it’s probably only a matter of time before it’s delivering video to your desktop. Remember that only a few years ago, a mere 100-Mbps was impressive enough to be called “Fast Ethernet.” collapse


    Black Box Explains...Remote access.

    Remote access is the ability to access a network, a personal computer, a server, or other device from a distance for the purpose of controlling it or to access data.... more/see it nowToday, remote access is usually accomplished over the Internet, although a local IP network, telephone lines, cellular service, or leased lines may also be used. With today’s ubiquitous Internet availability, remote access is increasingly popular and often results in significant cost savings by enabling greater network access and reducing travel to remote sites. Remote access is a very general term that covers a wide range of applications from telecommuting to resetting a distant server. Here are just a few of the applications that fall under the remote access umbrella:

    Remote network access
    A common use for remote access is to provide corporate network access to employees who work at home or are in sales or other traveling positions. This kind of remote access typically uses IPsec VPN tunnels to authenticate and secure connections.

    Remote desktop access
    Remote desktop access enables users to access a computer remotely from another computer and take control of it as if it were local. This kind of remote control requires that special software—which is included with most operating systems—be installed and enabled. It’s often used by those who travel frequently to access their “home” computer, and by network administrators for remote server access. This remote access method has some inherent security concerns and is usually incompatible with firewalls, so it’s important to be aware of its limitations and use adequate security precautions.

    Remote KVM access
    A common application in organizations that maintain servers across multiple sites is server administration through an IP-enabled KVM switch. These IP-addressable switches support one or more servers and have an integral Web server, enabling users to access them over the Internet through a Web browser. Because they’re intended for Internet use, these switches offer authentication and encryption for secure connections.

    Remote power management
    Anyone who’s ever had to get out of bed in the middle of the night to go switch a server off and back on again to reset it can appreciate the convenience of remote power management. Remote power managers have a wide range of capabilities ranging from simple power switching to reboot a device to sophisticated power monitoring, reporting, and management functions.

    Remote environmental security monitoring
    Remote environmental and security monitoring over the Internet is increasingly popular, largely because of the cost savings of using existing network infrastructure rather than a proprietary security system. This application requires IP-addressable hubs that support a variety of sensors ranging from temperature and humidity to power monitors. Some models even support surveillance cameras. collapse

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