|Friday, 18 August 2006|
Therefore, it is desirable to connect one or more user stations having associated peripherals to one or more computers, and to do so when the user stations and computers are at different locations. A keyboard/video/mouse (KVM) switching system is used for selectively interconnecting a single workstation with a plurality of remotely located computers. In such case, input/output devices such as a keyboard, a display monitor, and a mouse are typically connected to the plurality of computers with the aim of space and cost saving. KVM switches allow a single video display, character input device, and pointing device to communicate with one or more rack-mounted computers, and provide the user with the ability to access between two and eight different computers using a single keyboard, video and mouse.
KVM switch systems enable one or more remote computers to access and/or control one or more target computers. A single-user or multi-user KVM switch system allows the user of the workstation to switch access between various ones of the number of associated computers. The KVM switch can enable multiple computers to be accessed by means of a single set of keyboard, video display and mouse. The keyboard/video/mouse (KVM) switch is a signal switch that allows a single user or multiple users to share just a single keyboard, video device and mouse, or multiple sets of keyboards, video devices and mice. This is convenient in the situation in which a user accesses multiple computers such as an application server, a web or email server and a game box. The computer switch is connected between an input device and each of plural computers and is operative to activate the connection.
Although known KVM switches take a variety of configurations, their essential usuage is to allow a server or workstation (which consists of a keyboard, mouse and monitor) to interact with a selected computer to enable this computer receiving and transmitting understandable signals to and from the various workstation components regardless of the data protocol schemes employed by either the selected computer or the workstation devices. Most KVM switches employ a single user (single workstation) architecture in which a single keyboard, video, and monitor may access multiple numbers of computers. Multiple KVM switches can be cascaded to manage more servers than a single KVM switch can support. The keyboard, video and mouse are also attached to connections on the switch box which typically comprises a central processing unit (CPU) or microprocessor, a plurality of identical transmit/receive cards, a plurality of switch cards, a digital backplane and a separate analogue backplane. Such switch systems can be entirely re-programmed by downloading new program instructions (firmware) from a computer running a terminal program via a dedicated interface.
A KVM (keyboard, video display and mouse) switch connects a KVM console to the input/output devices and the plurality of computers and, simultaneously, functions so that connection of the input/output devices to only any one of the plurality of computers can be active. The KVM switch box will typically have at least one port for the workstation devices to provide and receive signals from the switch, together with a series of computer ports by which each of the associated computers is linked to the switch. A KVM switch typically responds to control information, provides status information, provides some type of security process, and passes data between user stations and computers. The control is switched from one computer to another by the use of buttons on the central analogue crosspoint switch, with the KVM passing the signals between the computers and the keyboard, mouse and monitor depending on which computer is currently selected.
KVM switches are typically based on packet-based Internet Protocol (IP) networks. This allows the peripherals to communicate with any one of the connected computers currently selected regardless of the data protocol used by any of the components connected to the KVM switch box. Signal conditioning interface units receive keyboard and mouse signals from a workstation and generate serial digital data packets which are transmitted to a switching hub comprising a central crosspoint switch. The crosspoint switch routes the keyboard/mouse packet to another signal conditioning interface unit coupled to the selected remote computer. KVM cables from each server can be connected to a KVM switch, and a set of KVM peripherals can be connected to the KVM switch to manage a number of servers. Typically, each computer is connected to the switch box using standard PS/2, USB and VGA cabling. A wireless KVM system connecting a target computer to a remote computer uses two radios, one at the target computer and the other at the remote computer.