USB True Emulation for KVM Switches. Transparent and reliable USB KVM switching technology.

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1 Tanspaent and eliable KVM switching technology blackbox.com

2 Table of Contents Intoduction... 3 Enumeated Switching... 4 Emulated Switching... 5 Tue Emulation... 6 About Black Box... 7 We e hee to help! If you have any questions about you application, ou poducts, o this white pape, contact Black Box Tech Suppot on o go to and click on Live Chat Page 2

3 Intoduction Remembe the good old days? Ca jouneys needed maps not satellites, mobile phones wee too lage to lose, and the Bakelite knob on you keyboad/video/mouse (KVM) switched you between computes in a manne moe befitting the age of steam than silicon. Since then, computes have advanced geatly in speed and sophistication. So too have thei peipheals and, in esponse, KVM switches have continually evolved to meet each new challenge. Howeve, one poblem has taditionally poved to be a tough nut to cack: how to switch devices tanspaently and eliably. The touble is that although appeas to be easy on the outside, thee s moe going on inside than you might expect. This has led to vaious difficulties that have spawned a numbe of possible solutions. Black Box Explains, a foce fo good connections. Since its inception in 1995, the Univesal Seial Bus () standad has poved to be an inceasingly successful way to connect a divese ange of devices and make them coopeate. Befoe, the back of any pesonal compute epesented a histoy lesson in stinging things togethe: Paallel pinte pots sat aside seial pots; keyboad and mouse connectos jostled with joystick pots, and SCSI sockets battled fo attention alongside FieWie links. Things ween t much bette at the font of the compute eithe, whee an endless seies of softwae dives and applications wee equied to pape ove the cacks that appeaed as each inteface method was pushed to its limits. Duing the 1990s, Apple Mac computes told a simila stoy, but with fewe difficulties. povided, and continues to povide, a common solution to all the applications mentioned above. It has succeeded pimaily because it s well suppoted, it s quick (in its vesion 2.0 fom), and it s easy to use. That ease of use comes about because it woks had in the backgound with a seies of caefully defined pocesses to ensue that devices and computes can opeate togethe in a coodinated manne Page 3

4 Enumeated Switching The ealiest attempts to switch devices applied a elatively hands off appoach. Remembe the old KVM switch with the mechanical knob and no intelligence? An enumeated switch is the electonic equivalent. The name is deived fom the initiation pocess (enumeation) that evey device goes though each time it is connected to a compute. With enumeated switches, a connected device is equied to pefom a full initiation evey time it is switched; just as if you had pulled out the plug and then econnected it. Enumeated switches simply pass all signals staight though between the device and the compute; they do not attempt to intepet any data. This is both a good and bad thing, depending on the type of devices that you ae using. Fo most devices, this offes an advantage because the switch just leaves them to get on with thei jobs without any intefeence o any dain on pefomance. The disadvantage is with keyboads and mice because you can no longe use them to contol the switching pocess a quick and simple contol method expected by most uses. Switching eliability is also an issue that has plagued enumeated switches, paticulaly when used with cetain devices and paticula opeating systems. The next challenge was obviously to make a moe eliable switch that could listen and eact to connected devices. Black Box Explains What is enumeation? The inteface was designed fom the outset to allow a wide vaiety of devices to be connected and disconnected fom the host compute at any time. A cucial pat of this pocess is called enumeation. As a device is connected, it intoduces itself to the host compute and the host allocates a unique identifying numbe between 1 and 127. This whole pocess takes between one and seven seconds (depending on the numbe of devices being connected and the opeating system) and must be done evey time that a device is connected to the host even if it has been peviously connected. Keyboad Mouse Connection to Device The inside view of a typical enumeated switch. The keyboad and mouse ae linked to a hub, which then feeds via a simple electonic switch to the selected compute. PC 1 PC 2 PC 3 PC Page 4

5 Emulated Switching Keyboad and mouse switching contol was pefected many yeas ago fo PS/2 style devices. Because of thei simplistic data steams, it was elatively staightfowad to ead thei inputs, stip out the switching contol infomation, and then epackage the emainde fo the compute. Achieving the same fo data steams has been much toughe with the added complexity of the standad and its signals. The poblem was eventually solved, with the emulated switch. As the name suggests, the chaacteistics of the attached device ae eceated, o emulated, once the equied switching contol infomation has been emoved fom the data steam. A neat side effect of the technique is that each compute can be fooled into thinking that the device is pemanently connected to it, even when the device is switched to anothe compute. This means that the enumeation pocess fo the device takes place only once, duing the fist time the device is poweed on. Afte that, a compute meely sees a domant vesion of the device wheneve the device is actually connected to a diffeent compute. Howeve, although emulated switches cued a numbe of shotfalls associated with thei enumeated cousins, thee still was one main limitation to thei opeation. It emained a complex task to dynamically assume the identity of a device, distibute it among the connected computes and maintain all the necessay signals, states, and pocesses. Theefoe, manufactues, including Black Box, elied upon a fixed keyboad and mouse pofile that is declaed to each compute, egadless of the actual connected devices. This pecluded the use of any special keyboad buttons o mouse featues ove and above the standad layouts. Keyboad Mouse Host Contolle CPU The inside view of a typical emulated switch. The keyboad and mouse ae linked to a host contolle (a sophisticated hub) and then though to the micopocesso (CPU) which pefoms the data captue and switching pocesses. PC 1 PC 2 PC 3 PC 4 The cuently active connection is then linked via a peipheal contolle to the selected compute Page 5

6 Tue Emulation To ovecome the limitations associated with even emulated switching techniques, Tue Emulation was developed. With Tue Emulation, the complete identity of the keyboad and mouse can be copied and then pesented to all the connected computes. This means that any keyboad offeing special function keys o any mouse with exta featues will be fully suppoted at each compute. As with the pevious emulation method, the unselected computes will continue to see the identities of the keyboad and mouse, which means that no enumeation is necessay when thei link becomes active once again. This not only helps to make econnecting faste, it also inceases switching eliability. This is impotant because links ae at thei most vulneable duing the enumeation pocess. In addition, a new high-speed cicuit handles all the equied exta tasks. Called the Emulation Engine, it fully emulates the device identities, and it intepets keyboad and mouse data steams. The esult is full suppot fo KVM switching contol via hotkey pesses o the thid button/scoll wheel of a mouse. Fo local installations, this is useful; fo emote applications, such as KVM via IP, it is essential. Keyboad Mouse Device Host Contolle Emulation Engine Because othe devices don't necessaily need the benefits of Tue Emulation like keyboads and mice do, thee ae one o even two enumeated cicuits (shown in geen within the diagam at ight) alongside the Tue Emulation featue (shown in blue). This enables the othe devices to opeate at thei highest speeds without any intevention. The enumeated cicuits benefit geatly fom the hubs that ae jointly used with the Tue Emulation system. Because they inteface diectly and pemanently with each compute, they help to stabilize the domant links, making eos duing enumeation much less likely. The dual switching aangement povides futhe flexibility because the Tue Emulation and enumeated sections can be switched in unison o independently of each othe, as equied. Thus, you vaious peipheals can opeate with diffeent computes at the same time. You can find Tue Emulation in a KVM switch nea (o fa fom) you soon, like in the Black Box SevSwitch Wizad 8-Pot DVI Dual-Link () (KV2008A), a pofessional desktop KVM switch with Tue Emulation technology. When a use connects devices, the SevSwitch Wizad 8-Pot DVI Dual Link () simultaneously and accuately emulates the chaacte of the devices to all computes. The use can shae high-end video and any fou peipheals between eight wokstations. The Wizad offes tue DDC EDID suppot and enables uses to switch up to eight PCs via hotkeys, mouse, o RS-232/V.24. It can be switched synchonously with othe SevSwitch Wizad switches, and the steeo audio switches independently fom the video signal. A 4-pot model (KV2004A) is also available. PC 1 PC 2 PC 3 PC 4 The inside view of a Tue Emulation switch. The emulated section of the switch is shown in blue and handles only the keyboad and mouse. This section elies heavily on the emulation engine, a custom cicuit that is closely allied with each of the hubs. These ensue that all connections to the computes emain active. The enumeated section of the switch is shown in geen and handles othe devices and also uses the hubs to link with the computes Page 6

7 About Black Box Black Box Netwok Sevices is a leading connectivity solutions povide, seving 175,000 clients in 141 counties with 193 offices thoughout the wold. Catalogue and on-line offeings fom Black Box include moe than 118,000 poducts including desktop, entepise, and IP-enabled KVM switches and hubs, switches, and extendes. The SevSwitch Wizad 8-Pot DVI Dual-Link () (KV2008A) is a pofessional desktop KVM switch with Tue Emulation technology. Black Box's extensive line of extendes includes CATx, fibe, and wieless. To view Black Box s compehensive offeing, see ou Web site at Black Box is also known as the wold s lagest technical sevices company dedicated to designing, building, and maintaining today s complicated data and voice infastuctue systems. Copyight All ights eseved. Black Box and the Double Diamond logo ae egisteed tademaks, and SevSwitch is a tademak, of BB Technologies, Inc. Any thid-paty tademaks appeaing in this white pape ae acknowledged to be the popety of thei espective ownes Page 7