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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...On-screen menus.

When the ServSwitch™ brand of KVM switches was first introduced, there were only two ways to switch: from front-panel push buttons or by sending command sequences from the keyboard. While... more/see it nowthis was more convenient than having a separate keyboard, monitor, and mouse for each CPU, the operator still had to remember key combinations and which server was connected to which port—leading to many cryptic, scribbled notes attached to the switch and to the workstation.

But with the advent of on-screen menus, an operator can use easy-to-read, pop-up menus to identify and select CPUs. It’s even possible to give each CPU a name that makes sense to you—names like “MIS Server,” “Accounting Server,” and so on.
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Black Box Explains... SC and ST connectors.

The SC Connector features a molded body and a push-pull locking system. It’s perfect for the office, CATV, and telephone applications.

The ST® Connector uses a bayonet locking system. Its... more/see it nowceramic ferrule ensures high performance. collapse


The difference between unmanaged, managed, and Web-smart switches

With regard to management options, the three primary classes of switches are unmanaged, managed, and Web smart. Which you choose depends largely on the size of your network and how... more/see it nowmuch control you need over that network.

Unmanaged switches are basic plug-and-play switches with no remote configuration, management, or monitoring options, although many can be locally monitored and configured via LED indicators and DIP switches. These inexpensive switches are typically used in small networks or to add temporary workgroups to larger networks.

Managed switches support Simple Network Management Protocol (SNMP) via embedded agents and have a command line interface (CLI) that can be accessed via serial console, Telnet, and Secure Shell. These switches can often be configured and managed as groups. More recent managed switches may also support a Web interface for management through a Web browser.

These high-end switches enable network managers to remotely access a wide range of capabilities including:

  • SNMP monitoring.
  • Enabling and disabling individual ports or port Auto MDI/MDI-X.
  • Port bandwidth and duplex control.
  • IP address management.
  • MAC address filtering.
  • Spanning Tree.
  • Port mirroring to monitor network traffic.
  • Prioritization of ports for quality of service (QoS).
  • VLAN settings.
  • 802.1X network access control.
  • IGMP snooping.
  • Link aggregation or trunking.

  • Managed switches, with their extensive management capabilities, are at home in large enterprise networks where network administrators need to monitor and control a large number of network devices. Managed switches support redundancy protocols for increased network availability.

    Web-smart switches—sometimes called smart switches or Web-managed switches—have become a popular option for mid-sized networks that require management. They offer access to switch management features such as port monitoring, link aggregation, and VPN through a simple Web interface via an embedded Web browser. What these switches generally do not have is SNMP management capabilities or a CLI. Web-smart switches must usually be managed individually rather than in groups.

    Although the management features found in a Web-smart switch are less extensive than those found in a fully managed switch, these switches are becoming smarter with many now offering many of the features of a fully managed switch. Like managed switches, they also support redundancy protocols for increased network availability.

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    Black Box Explains…Digital Visual Interface (DVI) connectors.

    The DVI (Digital Video Interface) technology is the standard digital transfer medium for computers while the HDMI interface is more commonly found on HDTVs, and other high-end displays.

    The Digital... more/see it nowVisual Interface (DVI) standard is based on transition-minimized differential signaling (TMDS). There are two DVI formats: Single-Link and Dual-Link. Single-link cables use one TMDS-165 MHz transmitter and dual-link cables use two. The dual-link cables double the power of the transmission. A single-link cable can transmit a resolution ?of 1920 x 1200 vs. 2560 x 1600 for a dual-link cable.

    There are several types of connectors: ?DVI-D, DVI-I, DVI-A, DFP, and EVC.

  • DVI-D is a digital-only connector for use between a digital video source and monitors. DVI-D eliminates analog conversion and improves the display. It can be used when one or both connections are DVI-D.
  • DVI-I (integrated) supports both digital and analog RGB connections. It can transmit either a digital-to-digital signals or an analog-to-analog signal. It is used by some manufacturers on products instead of separate analog and digital connectors. If both connectors are DVI-I, you can use any DVI cable, but a DVI-I is recommended.
  • DVI-A (analog) is used to carry an DVI signal from a computer to an analog VGA device, such as a display. If one or both of your connections are DVI-A, use this cable. ?If one connection is DVI and the other is ?VGA HD15, you need a cable or adapter ?with both connectors.
  • DFP (Digital Flat Panel) was an early digital-only connector used on some displays.
  • EVC (also known as P&D, for ?Plug & Display), another older connector, handles digital and analog connections.
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    Black Box Explains...10-GbE, CAT6A, and ANEXT.

    The IEEE released the 802.3an 10GBASE-T standard in June 2006. This standard specifies 10-Gbps data transmission over four-pair copper cabling. 10-Gigabit Ethernet (10-GbE) transmission includes up to 37 meters of... more/see it nowCAT6 cable (with installation mitigation techniques), 100 meters of Augmented Category 6 (CAT6A) UTP or F/UTP cable or 100 meters of S/FTP CAT7/Class F cable.

    CAT6A is the ANSI/TIA 10-Gigabit Ethernet (10-GbE) over copper standard. Its requirements are covered in ANSI/TIA-568-C.2 (Balanced Twisted-Pair Communications Cabling and Components Standard) published in August 2009. It defines 10-Gigabit data transmission over a 4-connector twisted-pair CAT6A copper cable for a distance of 100 meters.

    Category 6A cabling is designed to support next-generation applications, including the transfer of large amounts of data at high speeds, up to 10 Gbps. CAT6A extends electrical specifications to 500 MHz from 250 MHz for CAT6 cabling. CAT6A cables are fully backward compatible with previous categories, including CAT6 and 5e. Category 6A is also designed to support bundled cable installations up to 100 meters and PoE+ low-power implementations. The standard includes the performance parameter, Alien Crosstalk (ANEXT). Because of its higher performance transmission speeds and higher MHz rating, CAT6A cable needs to be tested for external noise outside the cable, which wasn’t a concern with previous cabling categories. CAT6A UTP also has a much larger diameter than previous cables.

    Alien crosstalk (ANEXT) is a critical and unique measurement in 10-GbE systems. Crosstalk, measured in 10/100/1000BASE-T systems, is the mixing of signals between wire pairs within a cable. Alien Crosstalk, in 10-GbE systems, is the measurement of the unwanted signal coupling between wire pairs in different and adjacent cables or from one balanced twisted-pair component, channel, or permanent link to another.

    The amount of ANEXT depends on a number of factors, including the type of cable, cable jacket, cable length, cable twist density, proximity of adjacent cables, and connectors, and EMI. Patch panels and connecting hardware are also affected by ANEXT.

    With Alien Crosstalk, the affected cable is called the victim cable. The surrounding cables are the disturber cables.

    There are a number of ways to mitigate the effects of ANEXT in CAT6A runs. According to the standards, ANEXT can be improved by laying CAT6A UTP cable loosely in pathways and raceways with space between the cables. This contrasts to the tightly bundled runs of CAT6/5e cable that we are used to. The tight bundles present a worst-case scenario of six cables around one, thus the center cable would be adversely affected by ANEXT. CAT6A UTP cable needs to be tested for ANEXT. This is a complex and time-consuming process in which all possible wire-pair combinations need to be tested for ANEXT and far-end ANEXT. It can take 50 minutes to test one link in a bundle of 24 CAT 6A UTP cables.

    To virtually eliminate the problem of ANEXT, you can use CAT6A F/UTP cable. The F indicates an outer foil shield encasing four unshielded twisted pairs. This cable is also a good choice when security is an issue because it doesn’t emit signals. In addition, CAT6A F/UTP cable works well in noisy environments with a lot of EMI/RFI.

    Installation of CAT6A F/UTP is simpler, too, because the cable features a smaller outside diameter than CAT6A UTP. Its construction makes it easier to pull and more resilient. The cable also has a smaller diameter so you can run more cables in a conduit or pathway, and have greater patch panel port density.

    For more information, see the CAT6A F/UTP vs. UTP: What You Need to Know white paper in the Resources section at blackbox.com. collapse


    Black Box Explains...Gigabit Ethernet.

    As workstations and servers migrated from ordinary 10-Mbps Ethernet to 100-Mbps speeds, it became clear that even greater speeds were needed. Gigabit Ethernet was developed for an even faster Ethernet... more/see it nowstandard to handle the network traffic generated on the server and backbone level by Fast Ethernet. Gigabit Ethernet delivers an incredible 1000 Mbps (or 1 Gbps), 100 times faster than 10BASE-T. At that speed, Gigabit Ethernet can handle even the traffic generated by campus network backbones. Plus it provides a smooth upgrade path from 10-Mbps Ethernet and 100-Mbps Fast Ethernet at a reasonable cost.

    Compatibility
    Gigabit Ethernet is a true Ethernet standard. Because it uses the same frame formats and flow control as earlier Ethernet versions, networks readily recognize it, and it’s compatible with older Ethernet standards. Other high-speed technologies (ATM, for instance) present compatibility problems such as different frame formats or different hardware requirements.

    The primary difference between Gigabit Ethernet and earlier implementations of Ethernet is that Gigabit Ethernet almost always runs in full-duplex mode, rather than the half-duplex mode commonly found in 10- and 100-Mbps Ethernet.

    One significant feature of Gigabit Ethernet is the improvement to the Carrier Sense Multiple Access with Collision Detection (CSMA/CD) function. In half-duplex mode, all Ethernet speeds use the CSMA/CD access method to resolve contention for shared media. For Gigabit Ethernet, CSMA/CD has been enhanced to maintain the 200-meter (656.1-ft.) collision diameter.

    Affordability and adaptability
    You can incorporate Gigabit Ethernet into any standard Ethernet network at a reasonable cost without having to invest in additional training, cabling, management tools, or end stations. Because Gigabit Ethernet blends so well with your other Ethernet applications, you have the flexibility to give each Ethernet segment exactly as much speed as it needs—and if your needs change, Ethernet is easily adaptable to new network requirements.

    Gigabit Ethernet is the ideal high-speed technology to use between 10-/100-Mbps Ethernet switches or for connection to high-speed servers with the assurance of total compatibility with your Ethernet network.

    When Gigabit Ethernet first appeared, fiber was crucial to running Gigabit Ethernet effectively. Since then, the IEEE802.3ab standard for Gigabit over Category 5 cable has been approved, enabling short stretches of Gigabit speed over existing copper cable. Today, you have many choices when implementing Gigabit Ethernet:

    1000BASE-X
    1000BASE-X refers collectively to the IEEE802.3z standards: 1000BASE-SX, 1000BASE-LX, and 1000BASE-CX.

    1000BASE-SX
    The “S“ in 1000BASE-SX stands for “short.“ It uses short wavelength lasers, operating in the 770- to 860-nanometer range, to transmit data over multimode fiber. It’s less expensive than 1000BASE-LX, but has a much shorter range of 220 meters over typical 62.5-µm multimode cable.

    1000BASE-LX
    The “L“ stands for “long.“ It uses long wavelength lasers operating in the wavelength range of 1270 to 1355 nanometers to transmit data over single-mode fiber optic cable. 1000BASE-LX supports up to 550 meters over multimode fiber or up to 10 kilometers over single-mode fiber.

    1000BASE-CX
    The “C“ stands for “copper.“ It operates over special twinax cable at distances of up to 25 meters. This standard never really caught on.

    Gigabit over CAT5—1000BASE-TX
    The 802.3ab specification, or 1000BASE-TX, enables you to run IEEE-compliant Gigabit Ethernet over copper twisted-pair cable at distances of up to 100 meters of CAT5 or higher cable.

    Gigabit Ethernet uses all four twisted pairs within the cable, unlike 10BASE-T and 100BASE-TX, which only use two of the four pairs. It works by transmitting 250 Mbps over each of the four pairs in 4-pair cable. 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


    Black Box Explains...SCSI-1, SCSI-2, SCSI-3, and SCSI-5.

    There are standards…and there are standards applied in real-world applications. This Black Box Explains illustrates how SCSI is interpreted by many SCSI manufacturers. Think of these as common SCSI connector... more/see it nowtypes, not as firm SCSI specifications. Notice, for instance, there’s a SCSI-5, which isn’t listed among the other approved and proposed specifications. However, for advanced SCSI multiport applications, SCSI-5 is often the connector of choice.

    SCSI-1
    Supports transfer rates up to 5 MBps and seven SCSI devices on an 8-bit bus. The most common connector is the Centronics® 50 or a DB50. A Micro Ribbon 50 is also used for internal connections. SCSI-1 equipment, such as controllers, can also have Burndy 60 or 68 connectors.

    SCSI-2
    SCSI-2 introduced optional 16- and 32-bit buses called “Wide SCSI.“ Transfer rate is normally 10 MBps but SCSI-2 can go up to 40 MBps with Wide and Fast SCSI. SCSI-2 usually features a Micro D 50-pin connector with thumbclips. It’s also known as Mini 50 or Micro DB50. A Micro Ribbon 60 connector may also be used for internal connections.

    SCSI-3
    Found in many high-end systems, SCSI-3 commonly uses a Micro D 68-pin connector with thumbscrews. It’s also known as Mini 68. The most common bus width is 16 bits with transfer rates of 20 MBps.

    SCSI-5
    SCSI-5 is also called a Very High-Density Connector Interface (VHDCI) or 0.8-mm connector. It’s similar to the SCSI-3 MD68 connector in that it has 68 pins, but it has a much smaller footprint. SCSI-5 is designed for SCSI-5, next-generation SCSI connections. Manufacturers are integrating this 0.8-mm design into controller cards. It’s also the connector of choice for advanced SCSI multiport applications. Up to four channels can be accommodated in one card slot. Connections are easier where space is limited. collapse


    Black Box Explains...CAT5: When more isn’t always better.

    In data communications applications, using products that exceed required capacities is usually not a problem. For example, if a 28.8K modem is required, a 33.6K or 56K model will work... more/see it nowjust fine.

    But sometimes, more isn’t better. Take KVM extenders designed to expect CAT5 and only CAT5 cable. You’d expect that Category 3 cable wouldn’t be effective with these products, and you would be right.

    But you may also assume that if Category 5 cable works fine, Category 5e, Category 6, and other higher-capacity cables would work even better. Unfortunately, this isn’t the case, and here’s why:

    KVM extenders from many manufacturers, including ServSwitch CAT5 KVM Extenders, are designed specifically for the Category 5 specs defined by the TIA/EIA standard. Higher-level cables, such as Category 5e, have different characteristics and specifications. Although differences—specifically twist ratios—might seem small, they can have a negative impact on these extenders, which are expecting a true Category 5 transmission.

    So with ServSwitch CAT5 KVM Extenders, you can think big with CAT5—just don’t think bigger. collapse

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