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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…Energy-Efficient Ethernet.

The IEEE 802.3az Ethernet standard, ratified in 2010, provides a standardized way for some Ethernet devices to reduce power consumption. Energy-Efficient Ethernet devices have a low-power idle (LPI) mode that... more/see it nowcan cut power use by 50% or more during periods of low data activity. Because energy-efficient Ethernet devices scale down power consumption when the load is lower, they save both the energy used to power processors and the energy used to cool them.

These energy savings are currently available for 100BASE-TX, 1000BASE-T, and 10GBASE-T Ethernet as well as some backplane Ethernet. 802.3az can be found on most types of network equipment, including NICs, switches, routers, and media converters. Because these devices are totally backwards compatible with other Ethernet devices, all you need to do to reap energy savings is to swap out devices. 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...Wireless Ethernet standards.

    IEEE 802.11
    The precursor to 802.11b, IEEE 802.11 was introduced in 1997. It was a beginning, but 802.11 only supported speeds up to 2 Mbps. And it supported two entirely different... more/see it nowmethods of encoding—Frequency Hopping Spread Spectrum (FHSS) and Direct Sequence Spread Spectrum (DSSS). This led to confusion and incompatibility between different vendors’ equipment.

    IEEE 802.11b
    802.11b is comfortably established as the most popular wireless standard. With the IEEE 802.11b Ethernet standard, wireless is fast, easy, and affordable. Wireless devices from all vendors work together seamlessly. 802.11b is a perfect example of a technology that has become both sophisticated and standardized enough to really make life simpler for its users.

    The 802.11b extension of the original 802.11 standard boosts wireless throughput from 2 Mbps all the way up to 11 Mbps. 802.11b can transmit up to 200 feet under good conditions, although this distance may be reduced considerably by the presence of obstacles such as walls.

    This standard uses DSSS. With DSSS, each bit transmitted is encoded and the encoded bits are sent in parallel across an entire range of frequencies. The code used in a transmission is known only to the sending and receiving stations. By transmitting identical signals across the entire range of frequencies, DSSS helps to reduce interference and makes it possible to recover lost data without retransmission.

    IEEE 802.11a
    The 802.11a wireless Ethernet standard is new on the scene. It uses a different band than 802.11b—the 5.8-GHz band called U-NII (Unlicensed National Information Infrastructure) in the United States. Because the U-NII band has a higher frequency and a larger bandwidth allotment than the 2.4-GHz band, the 802.11a standard achieves speeds of up to 54 Mbps. However, it’s more limited in range than 802.11b. It uses an orthogonal frequency-division multiplexing (OFDM) encoding scheme rather than FHSS or DSSS.

    IEEE 802.11g
    802.11g is an extension of 802.11b and operates in the same 2.4-GHz band as 802.11b. It brings data rates up to 54 Mbps using OFDM technology.

    Because it's actually an extension of 802.11b, 802.11g is backward-compatible with 802.11b—an 802.11b device can interface directly with an 802.11g access point. However, because 802.11g also runs on the same three channels as 802.11b, it can crowd already busy frequencies.

    Super G® is a subset of 802.11g and is a proprietary extension of the 802.11g standard that doubles throughput to 108 Mbps. Super G is not an IEEE approved standard. If you use it, you should use devices from one vendor to ensure compatibility. Super G is generally backwards compatible with 802.11g.

    802.11n
    80211n improves upon 802.11g significantly with an increase in the data rate to 600 Mbps. Channels operate at 40 MHz doubling the channel width from 20 MHz. 802.11n operates on both the 2.4 GHz and the 5 GHz bands. 802.11n also added multiple-input multiple-output antennas (MIMO).

    MIMO
    Multiple-Input/Multiple-Output (MIMO) is a part of the new IEEE 802.11n wireless standard. It’s a technique that uses multiple signals to increase the speed, reliability, and coverage of wireless networks. It transmits multiple datastreams simultaneously, increasing wireless capacity to up to 100 or even 250 Mbps.

    This wireless transmission method takes advantage of a radio transmission characteristic called multipath, which means that radio waves bouncing off surfaces such as walls and ceilings will arrive at the antenna at fractionally different times. This characteristic has long been considered to be a nuisance that impairs wireless transmission, but MIMO technology actually exploits it to enhance wireless performance.

    MIMO sends a high-speed data stream across multiple antennas by breaking it into several lower-speed streams and sending them simultaneously. Each signal travels multiple routes for redundancy.

    To pick up these multipath signals, MIMO uses multiple antennas and compares signals many times a second to select the best one. A MIMO receiver makes sense of these signals by using a mathematical algorithm to reconstruct the signals. Because it has multiple signals to choose from, MIMO achieves higher speeds at greater ranges than conventional wireless hardware does. collapse


    Black Box Explains...Link loss.

    Media converters solve the problem of connecting different media types in mixed-media networks. In order to comply with IEEE standards, they implement IEEE data-encoding rules and the Link Integrity Test.

    For... more/see it nowa twisted-pair segment, a link is a signal sent by the converters when the cable is in use. If no Link Integrity Test signal is received, the connected device assumes that the link is lost.

    With fiber cable, a connected device checks a line by monitoring the Link Integrity Test signal from the converter and the power of the light being received. If the light’s power drops below a certain threshold, the link is lost. In either case, link loss usually results from a broken cable, which is the cause of approximately 70% of all LAN problems.

    Link loss is often indicated by an LED on a connected network device. You can also monitor a link with network-management software, such as SNMP, which sends a TRAP (alert) to the management workstation when the link is lost.

    Media converters actually function as two separate Multistation Access Units (MAUs). For example, one monitor is a twisted-pair segment and one monitor is a fiber segment. If a fiber cable is broken and the link is lost, a network manager on the twisted-pair end won’t know there’s a problem until users on the fiber side report it.

    To solve this problem, Black Box® Modular Media Converters feature a unique Link-Loss capability. This enables the link status on one segment to reflect the link status of the other segment. So if the link is lost on the fiber side, the link is disabled on the UTP segment as well. And the converters will send an SNMP TRAP indicating the loss of link to the management workstation. collapse


    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... Why go wireless?

    • It’s great for communicating in harsh climates or in areas where it’s expensive to run cable. Wireless solutions are well suited for use in military applications, farming, refineries, mining,... more/see it nowconstruction, and field research.
    • Because sometimes you just can’t run wire, like in historic buildings or hazmat areas.
    • When it’s physically or legally impossible to support conventional hard-wired RS-232 communications, wireless networking may be your only answer.
    • It gives you quick, temporary connections at trade shows, and fast reconfigurations—even troubleshooting or remote field testing.
    • It provides reliable disaster relief when all else fails! Count on wireless networks to maintain mission-critical links when disaster strikes.
    • It’s more affordable, more reliable, and faster than ever before.
    • Best of all, no FCC licensing required! collapse


    Black Box Explains...MIMO wireless.

    Multiple-Input/Multiple-Output (MIMO) is a part of the new IEEE 802.11n wireless standard. It’s a technique that uses multiple signals to increase the speed, reliability, and coverage of wireless networks. It... more/see it nowtransmits multiple datastreams simultaneously, increasing wireless capacity to up to 100 or even 250 Mbps.

    This wireless transmission method takes advantage of a radio transmission characteristic called multipath, which means that radio waves bouncing off surfaces such as walls and ceilings will arrive at the antenna at fractionally different times. This characteristic has long been considered to be a nuisance that impairs wireless transmission, but MIMO technology actually exploits it to enhance wireless performance.

    MIMO sends a high-speed data stream across multiple antennas by breaking it into several lower-speed streams and sending them simultaneously. Each signal travels multiple routes for redundancy.

    To pick up these multipath signals, MIMO uses multiple antennas and compares signals many times a second to select the best one. A MIMO receiver makes sense of these signals by using a mathematical algorithm to reconstruct the signals. Because it has multiple signals to choose from, MIMO achieves higher speeds at greater ranges than conventional wireless hardware does. collapse


    Non-standard PoE

    Because Power over Ethernet (PoE) delivers power over the same cable as data, it’s popular for powering devices such as VoIP phones, wireless access points, and security cameras. It often... more/see it nowleads to significant savings by eliminating the need to install a separate power outlet.

    Most PoE today is standards-based IEEE 802.3af or the newer higher-powered IEEE 802.3at PoE, which are very safe because power source equipment (PSE) doesn’t add power to the data line unless it detects a compatible powered device (PD) connected to the other end of the cable. This protects devices that do not support PoE. PSEs and PDs also negotiate power requirements, so a PD never receives too much power. Both PSEs and PDs have power supplies and regulators isolated from ground to minimize shock hazard.

    But here’s where it gets complicated…
    Because most PoE available today is standards-based 802.3af or 802.3at, it’s easy to forget that there are versions of PoE that are NOT standards based. Some of these non-standards-based versions of PoE feature power injectors that inject power without checking compatibility—and that can be very bad news for an innocent network device.

    Non-standard PoE tends to fall into three categories: proprietary PoE, high-wattage proprietary PoE, and passive PoE.

    Proprietary PoE.
    Before the ratification of the 802.3af standard in 2003, PoE was a free-for-all with many vendors offering their own method of delivering power over data lines. Some vendors still offer their own proprietary PoE. These proprietary solutions offer varying degrees of communication between PSE and PD. Our Black Box® Wireless Point-to-Point Ethernet Extender Kit (LWE100A-KIT) uses Prorietary PoE in the form of 12 VDC running at 12 W, which is well below the 48 VDC and 15.4 W provided by standard 802.3af.

    High-wattage Proprietary PoE.
    Many vendors offer high-wattage PoE solutions designed to deliver from 50 watts to 100 or even 200 watts per port. High-wattage proprietary PoE is often used with high-powered outdoor wireless radios.

    Passive PoE.
    Passive PoE injects power into an Ethernet cable on Pins 4 and 5 with negative return on Pins 7 and 8 and absolutely no communication between PSE and PD. This method was once a very common “home brew” method of transferring power over data cable and is still commonly used in telecomm applications.

    Document and label.
    There’s nothing wrong with PoE that’s not standards based—these power methods work as well as 802.3af/at PoE to power network devices. You do, however, need to be aware of what kind of Power over Ethernet you have and what it will work with. Good network documentation and labeling are the keys that enable you to know that, for instance, that power injector is a high-wattage proprietary injector that will fry the IP camera you’re about to connect. Proper documentation, which is good practice in any case, becomes absolutely vital when you have components that may damage other components.
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    Black Box Explains…A terminal server by any other name.

    A terminal server (sometimes called a serial server or a console server or a device server) is a hardware device that enables you to connect serial devices across a network.

    Terminal... more/see it nowservers acquired their name because they were originally used for long-distance connection of dumb terminals to large mainframe systems such as VAX™. Today, the name terminal server refers to a device that connects any serial device to a network, usually Ethernet. In this day of network-ready devices, terminal servers are not as common as they used to be, but they’re still frequently used for applications such as remote connection of PLCs, sensors, or automatic teller machines.

    The primary advantage of terminal servers is that they save you the cost of running separate RS-232 devices. By using a network, you can connect serial devices even over very long distances—as far as your network stretches. It’s even possible to connect serial devices across the Internet. A terminal server connects the remote serial device to the network, and then another terminal server somewhere else on the network connects to the other serial device.

    Terminal servers act as virtual serial ports by providing the appropriate connectors for serial data and also by grouping serial data in both directions into Ethernet TCP/IP packets. This conversion enables you to connect serial devices across Ethernet without the need for software changes.

    Because terminal servers send data across a network, security is a consideration. If your network is isolated, you can get by with an inexpensive terminal server that has few or no security functions. But if you’re using a terminal server to make network connections across a network that’s also an Internet subnet, you should look for a terminal server that offers extensive security features. collapse

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