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Black Box Explains...Terminal Servers

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

Terminal servers acquired their name because they were originally... more/see it nowused 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. If, however, 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


Black Box Explains...KVMoIP access technology.

KVMoIP access technology extends keyboard, video, and mouse (KVM) signals from any computer or server over TCP/IP via a LAN, WAN, or Internet connection. Through this KVM over IP (KVMoIP)... more/see it nowconnection, remote users can access and control a number of servers simultaneously from wherever they are, inside or outside the organization, and anywhere in the world. This technology works in diverse hardware environments and is ideal for managing multilocation data centers and branch offices.

These capabilities translate into real savings for companies having to deal with the proliferation of servers in many offices, particularly for corporations and government agencies required to deliver 24/7 uptime and real-time access to mission-critical servers 365 days a year.

KVMoIP products combine the advantages of remote access software with the benefits of KVM switching technology. Like most KVM switches, KVMoIP products don’t require any software to be loaded on the host computers. They interface directly with the keyboard, monitor, and mouse connectors of the host computer or KVM switch. Circuitry within the KVMoIP device digitizes the incoming video signal and processes it into digital data that is communicated to a viewer program running on a remote client computer over a LAN/WAN or the public Internet.

By addressing network issues from a remote location, you can simply manage issues from your desk, or even save yourself the hassle of traveling to a site in the middle of the night. Use a browser-based connection, even a cell phone or PDA, to reboot or administer a roomful of servers remotely—a real convenience.

KVMoIP products that feature virtual media technology take that convenience further. They enable a remote user to effortlessly move files from a mass storage device—a USB flash drive or CD-ROM drive, for instance—from your location to the computer on which you’re working. Cost savings are realized through reduced downtime and less travel. Plus, in some cases, there‘s no to need replace existing KVM switches with proprietary ones to get a KVMoIP server-control solution.

The Black Box difference
Black Box® ServSwitch™ KVMoIP solutions go further than many other KVMoIP products on the market. They not only enable you to access remote servers, but they do this at the BIOS level—important when you go need to troubleshoot from off-site and don’t want to a dispatch a technician. Install or recover software applications and install OS patches from your location anywhere in the world. Plus, this BIOS-level control is possible regardless of the server’s brand or model and even works if the operating system is down.

The ServReach™ system is also designed for IT managers seeking global centralized KVM management in a world of mushrooming servers and complexity. This global platform works by consolidating all server access and devices via locally connected KVMoIP devices. All this hardware is then united under a single management appliance or software “umbrella” providing global, yet fully secure, out-of-band control.

The ServReach system works seamlessly with more than 500 variations of analog KVM switches from a multitude of vendors and manufacturers. Because it’s vendor independent, you don’t need to replace your data center’s entire KVM infrastructure. ServReach simply grafts global centralized KVM management onto the existing server room/data center, aligning with third-party KVM switches already in place. This is done with the ServReach KVMGate (KVIP1000A), an IP gateway device designed to connect to each of the legacy KVM devices to provide global centralized KVM management for a fraction of the cost of competitive systems, ensuring a faster and greater ROI.

If you’re planning on opening or acquiring a new data center or a large number of new servers, the ServReach KVManager (KVMGR) is the answer. It can provide any-by-any access via the ServReach KVMCube (KVIP1001A), a compact, rackmountable, digital matrix IP device that gives fully secure, non-blocking access for any of the users to any of the servers simultaneously.

In addition, the servers controlled by legacy KVM switches via KVMGate can still be managed by the ServReach KVManager at the same time as the new servers controlled through a gateway. With all the servers under the same KVManager umbrella, data centers can now easily acquire new servers and devices without having to worry about how to incorporate the new infrastructure with the old. For more information on Black Box KVMoIP solutions, visit blackbox.com/go/ServReach. Find out more by watching a KVMoIP demo and accessing related white papers. 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...How a line driver operates.

    Driving data? Better check the transmission.

    Line drivers can operate in any of four transmission modes: 4-wire full-duplex, 2-wire full-duplex, 4-wire half-duplex, and 2-wire half-duplex. In fact, most models support more... more/see it nowthan one type of operation.

    So how do you know which line driver to use in your application?

    The deal with duplexing.
    First you must decide if you need half- or full-duplex transmission. In half-duplex transmission, voice or data signals are transmitted in only one direction at a time, In full-duplex operation, voice or data signals are transmitted in both directions at the same time. In both scenarios, the communications path support the full data rate.

    The entire bandwidth is available for your transmission in half-duplex mode. In full-duplex mode, however, the bandwidth must be split in two because data travels in both directions simultaneously.

    Two wires or not two wires? That is the question.
    The second consideration you have is the type of twisted-pair cable you need to complete your data transmissions. Generally you need twisted-pair cable with either two or four wires. Often the type of cabling that’s already installed in a building dictates what kind of a line driver you use. For example, if two twisted pairs of UTP cabling are available, you can use a line driver that operates in 4-wire applications, such as the Short-Haul Modem-B Async or the Line Driver-Dual Handshake models. Otherwise, you might choose a line driver that works for 2-wire applications, such as the Short-Haul Modem-B 2W or the Async 2-Wire Short-Haul Modem.

    If you have the capabilities to support both 2- and 4-wire operation in half- or full-duplex mode, we even offer line drivers that support all four types of operation.

    As always, if you’re still unsure which operational mode will work for your particular applications, consult our Technical Support experts and they’ll help you make your decision. collapse


    Black Box Explains... KVM IP gateways

    Just as a gate serves as an entry or exit point to a property, a gateway serves the same purpose in the networking world. It’s the device that acts as... more/see it nowa network entrance or go-between for two or more networks.

    There are different types of gateways, depending on the network.

    An application gateway converts data or commands from one format to another. A VoIP gateway converts analog voice calls into VoIP packets. An IP gateway is like a media gateway, translating data from one telecommunications device to another.

    Gateways often include other features and devices, such as protocol converters, routers, firewalls, encryption, voice compression, etc. Although a gateway is an essential feature of most routers, other devices, such as a PC or server, can also function as a gateway.

    A KVMoIP switch contains an IP gateway, which is the pathway the KVM signals use to travel from the IP network to an existing non-IP KVM switch. It converts and directs the KVM signals, giving a user access to and control of an existing non-IP KVM switch over the Internet. 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...Multicasting video over a LAN: Use the right switch.

    In KVM extension applications where you want to distribute HD video across a network, you need to understand how it works and what kind of networking equipment to use with... more/see it nowyour extenders.

    Think of your network as a river of data with a steady current of data moving smoothly down the channel. All your network users are like tiny tributaries branching off this river, taking only as much water (bandwidth) as they need to process data. When you start to multicast video, data, and audio over the LAN, those streams suddenly become the size of the main river. Each user is then basically flooded with data and it becomes difficult or impossible to do any other tasks. This scenario of sending transmissions to every user on the network is called broadcasting, and it slows down the network to a trickle. There are network protocol methods that alleviate this problem, but it depends on the network switch you use.

    Unicast vs. multicasting, and why a typical Layer 2 switch isn’t sufficient.
    Unicasting is sending data from one network device to another (point to point); in a typical unicast network, Layer 2 switches easily support these types of communications. But multicasting is transmitting data from one network device to multiple users. When multicasting with Layer 2 switches, all attached devices receive the packets, whether they want them or not. Because a multicast header does NOT have a destination IP address, an average network switch (a Layer 2 switch without supported capabilities) will not know what to do with it. So the switch sends the packet out to every network port on all attached devices. When the client or network interface card (NIC) receives the packet, it analyzes it and discards it if not wanted.

    The solution: a Layer 3 switch with IGMPv2 or IGMPv3 and packet forwarding.
    Multicasting with Layer 3 switches is much more efficient than with Layer 2 switches because it identifies the multicast packet and sends it only to the intended receivers. A Layer 2 switch sends the multicast packets to every device and, If there are many sources, the network will slow down because of all the traffic. And, without IGMPv2 or IGMPv3 snooping support, the switch can handle only a few devices sending multicasting packets.

    Layer 3 switches with IGMP support, however, “know” who wants to receive the multicast packet and who doesn’t. When a receiving device wants to tap into a multicasting stream, it responds to the multicast broadcast with an IGMP report, the equivalent of saying, “I want to connect to this stream.” The report is only sent in the first cycle, initializing the connection between the stream and receiving device. If the device was previously connected to the stream, it sends a grafting request for removing the temporary block on the unicast routing table. The switch can then send the multicast packets to newly connected members of the multicast group. Then, when a device no longer wants to receive the multicast packets, it sends a pruning request to the IGMP-supported switch, which temporarily removes the device from the multicast group and stream.

    Therefore, for multicasting, use routers or Layer 3 switches that support the IGMP protocol. Without this support, your network devices will be receiving so many multicasting packets, they will not be able to communicate with other devices using different protocols, such as FTP. Plus, a feature-rich, IGMP-supported Layer 3 switch gives you the bandwidth control needed to send video from multiple sources over a LAN. collapse


    Black Box Explains... Industrial modem benefits.

    Not all modems shuttle data in air-conditioned, climate-controlled comfort. And modems that operate in cozy environments have absolutely no business being exposed to harsh industrial conditions or to the elements.

    But... more/see it nowjust because you work in a rough-and-tumble place doesn’t mean you have to sacrifice the convenience of a good modem. Instead, you should opt for an industrial modem. There are many industrial modems built for various degrees of extremity.

    Survivability depends on reliability.
    Sure, standard modems give you access to data in remote sites or enable you to service equipment on the plant floor—and you can do all this from the convenience of your office. However, these benefits are only possible if your modem can continue to function in its environment. And since standard modems aren’t built for adverse conditions, they’re not going to be reliable.

    No penalties for interference.
    Electrical control equipment—such as motors, relays, compressors, and generators—emit electromagnetic interference (EMI) that can affect the performance and reliability of a standard telephone modem.

    EMI is emitted through power lines, the RS-232 communications cable, or through the telephone line itself. The very means of data communication, cable, is often the worst enemy of the standard modems that use it.

    An industrial modem, on the other hand, has filters and superior EMI immunity to protect itself and your data. If you build your electrical cabinets to UL® or CSA standards, remember that your modem must also conform to UL® standard 508.

    They go to extremes.
    Temperature is the biggest killer of electronic equipment in industrial environments. The heat generated by industrial equipment in sealed enclosures or where space is a premium can make the temperature as much as 50 °F higher than the surrounding environment.

    So standard modems can’t take the heat. But what about being outdoors in the other extreme, cold weather? Well, standard modems can’t take the cold either.

    If you install your equipment in remote outdoor locations, it must work on the coldest days— especially those cold days when you least want to get in the car and go to the site to repair a standard modem that froze up.

    Whether they’re placed in manufacturing environments or the great outdoors, industrial modems get the data through when you need it. They go to extremes for you.

    Heavy metal for all kinds of banging around.
    Industrial modems are built with durable metal enclosures that protect circuitry in rough conditions and ward off signal-disrupting EMI. Plus, they feature steel-bolt flanges to anchor them. In short, industrial modems can take the physical, heavy-duty punishment thrown their way.

    So where exactly can you use an industrial modem?
    • Heavy industry and manufacturing
    • Oil and gas fields
    • Refineries
    • Storage sites
    • Utility substations
    • Agricultural projects
    • Military facilities
    • Research installations
    • Water/wastewater systems

    …and another thing!
    If dedicated copper lines can’t be run through industrial environments, or if the fiber optic option is cost-prohibitive, there are also wireless industrial modems that make line-of-sight connections. If there’s a way to get the data through, industrial modems will get the job done.

    Industrial-strength assurance.
    Industrial modems remain in service for a very long time. But if you ever need a replacement that is hardware or software compatible, be assured that Black Box continues to support its products year after year—so you don’t spend your time re-engineering systems if you have to make a replacement. collapse


    Black Box Explains...KVM tray technology.

    KVM tray technology. What we do that others don’t.
    From the solid construction of our KVM trays, to unique features like LEDs on the ?front panel and integrated KVM switching, Black Box’s... more/see it nowKVM trays are miles ahead of the competition.

    Nothing reduces clutter in a server room like KVM trays that are 1- or 2U high, and ?mount in a cabinet or rack. Here are some of the features that set our KVM trays apart.

    TFT LCD support.
    This type of monitor uses thin-film transistor (TFT) technology to improve image quality, resulting in higher resolutions, better image contrast, and addressability. All our KVM trays support TFT LCD panel monitors.

    Viewing angles.
    The screens on our KVM trays are viewable from nearly any angle. Because of the size of our screens, from 15" to 19", viewing angles vary from 140° x 120° all the way up to 160° x 160°, so you don’t always have to be standing directly in front of the monitor to see what’s happening on it.

    Universal rail.
    Our ServTray Complete family of KVM trays (KVT417A-R2, etc.) has adjustable length instead of a variety of rear bracket sites. This universal rail rear bracket size fits racks with depths of 23.7" (60.2 cm) to 45.3" (115 cm). This simplifies ordering for you!

    Dual rail technology.
    This KVM tray technology enables the monitor drawer and the keyboard/mouse drawer to move independently of each other. It makes it easy to leave the monitor visible even when a server cabinet is closed and the keyboard/mouse drawer is fully retracted. Black Box has added switching controls to the monitor bezel that can be used to control an attached switch without pulling open the keyboard/mouse drawer for even more space-saving benefits.

    Additionally, the dual rails provide a great monitoring environment without disturbing your cooling system.

    You asked for it.
    Our latest KVM trays, the ServView V KVM Drawer and ServView V KVM Drawer with Widescreen (KVT517A, etc.) were designed based on feedback we have received from some of our customers.

    On the front panel of the tray, there is an LED panel, which helps you locate the ?drawer when it’s closed in a darkened data center. The tray only takes up 1U of rack space, and it features the dual rail technology described earlier.

    We added front-panel controls for switching, so if you choose a model with an embedded KVM switch, you can use the buttons on the monitor bezel without pulling out the keyboard. Additionally, the top of the keyboard tray features a hideaway connection for USB wireless devices, such as RF- or Bluetooth® supported keyboards and mice. You can wirelessly access your attached targets, even without opening the cabinet door!

    Another feature is the front-panel USB port, which provides crash cart access. If your keyboard or GlidePoint® mouse quit on you, simply use this port to attach a passthrough pointing device.

    Finally, the widescreen version supports 1920 x 1080 resolutions and DVI connections — two firsts in the data center. collapse


    Black Box Explains...50-micron vs. 62.5-micron fiber optic cable.

    The background
    As today’s networks expand, the demand for more bandwidth and greater distances increases. Gigabit Ethernet and the emerging 10 Gigabit Ethernet are becoming the applications of choice for current... more/see it nowand future networking needs. Thus, there is a renewed interest in 50-micron fiber optic cable.

    First used in 1976, 50-micron cable has not experienced the widespread use in North America that 62.5-micron cable has.

    To support campus backbones and horizontal runs over 10-Mbps Ethernet, 62.5 fiber, introduced in 1986, was and still is the predominant fiber optic cable because it offers high bandwidth and long distance.

    One reason 50-micron cable did not gain widespread use was because of the light source. Both 62.5 and 50-micron fiber cable can use either LED or laser light sources. But in the 1980s and 1990s, LED light sources were common. Since 50-micron cable has a smaller aperture, the lower power of the LED light source caused a reduction in the power budget compared to 62.5-micron cable—thus, the migration to 62.5-micron cable. At that time, laser light sources were not highly developed and were rarely used with 50-micron cable—mostly in research and technological applications.

    Common ground
    The cables share many characteristics. Although 50-micron fiber cable features a smaller core, which is the light-carrying portion of the fiber, both 50- and 62.5-micron cable use the same glass cladding diameter of 125 microns. Because they have the same outer diameter, they’re equally strong and are handled in the same way. In addition, both types of cable are included in the TIA/EIA 568-B.3 standards for structured cabling and connectivity.

    As with 62.5-micron cable, you can use 50-micron fiber in all types of applications: Ethernet, FDDI, 155-Mbps ATM, Token Ring, Fast Ethernet, and Gigabit Ethernet. It is recommended for all premise applications: backbone, horizontal, and intrabuilding connections, and it should be considered especially for any new construction and installations. IT managers looking at the possibility of 10 Gigabit Ethernet and future scalability will get what they need with 50-micron cable.

    Gaining ground
    The big difference between 50-micron and 62.5-micron cable is in bandwidth. The smaller 50-micron core provides a higher 850-nm bandwidth, making it ideal for inter/intrabuilding connections. 50-micron cable features three times the bandwidth of standard 62.5-micron cable. At 850-nm, 50-micron cable is rated at 500 MHz/km over 500 meters versus 160 MHz/km for 62.5-micron cable over 220 meters.

    Fiber Type: 62.5/125 µm
    Minimum Bandwidth (MHz-km): 160/500
    Distance at 850 nm: 220 m
    Distance at 1310 nm: 500 m

    Fiber Type: 50/125 µm
    Minimum Bandwidth (MHz-km): 500/500
    Distance at 850 nm: 500 m
    Distance at 1310 nm: 500 m

    As we move towards Gigabit Ethernet, the 850-nm wavelength is gaining importance along with the development of improved laser technology. Today, a lower-cost 850-nm laser, the Vertical-Cavity Surface-Emitting Laser (VCSEL), is becoming more available for networking. This is particularly important because Gigabit Ethernet specifies a laser light source.

    Other differences between the two types of cable include distance and speed. The bandwidth an application needs depends on the data transmission rate. Usually, data rates are inversely proportional to distance. As the data rate (MHz) goes up, the distance that rate can be sustained goes down. So a higher fiber bandwidth enables you to transmit at a faster rate or for longer distances. In short, 50-micron cable provides longer link lengths and/or higher speeds in the 850-nm wavelength. For example, the proposed link length for 50-micron cable is 500 meters in contrast with 220 meters for 62.5-micron cable.

    Migration
    Standards now exist that cover the migration of 10-Mbps to 100-Mbps or 1 Gigabit Ethernet at the 850-nm wavelength. The most logical solution for upgrades lies in the connectivity hardware. The easiest way to connect the two types of fiber in a network is through a switch or other networking “box.“ It is not recommended to connect the two types of fiber directly. collapse

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