Editing KVM switch (section)

==Remote KVM extenders==

{{Unreferenced section|find=Remote KVM over IP|date=November 2023}}

There are two types of remote KVM extenders that are best described as local remote and KVM over IP.

===Local remote  (including KVM over USB)===
Local remote KVM extender design allows users to control computer equipment up to {{convert|1000|ft|m}} away from the user consoles (keyboard, monitor and mouse). They require a direct cable connection from the computer to the KVM extender to the console<ref name=understanding-the-four-categories-of-kvm-switches>{{Cite web|url=https://www.raritan.com/blog/detail/understanding-the-four-categories-of-kvm-switches|title=Understanding the Four Categories of KVM Switches - Raritan|website=www.raritan.com}}</ref> and include support for standard [[Category 5 cable|category 5 cabling]] between computers and users interconnected by the extender. In contrast, [[USB]] powered KVM extenders are able to control computer equipment using a combination of USB, keyboard, mouse and monitor cables of up to {{convert|5|m|ft}}.<ref>{{Cite web|url=https://www.epiphan.com/products/kvm2usb/|title=KVM2USB}}</ref>

==={{anchor|IPKVM}}KVM over IP (IPKVM)===
KVM switch over IP extenders use a dedicated micro-controller and potentially specialized video capture hardware to capture the video, keyboard, and mouse signals, compress and convert them into packets, and send them over an [[Ethernet]] link to a remote console application that unpacks and reconstitutes the dynamic graphical image.  KVM over IP subsystem is typically connected to a system's standby power plane so that it's available during the entire BIOS boot process.
These extender devices allow multiple computers to be controlled locally or globally with the use of an IP connection.<ref name=understanding-the-four-categories-of-kvm-switches /> There are performance issues related with LAN/WAN hardware, standard protocols and network latency so user management is commonly referred to as "near real time".

Access to most remote or "KVM" over IP extenders today use a [[web browser]], although many of the stand-alone viewer software applications provided by many manufacturers are also reliant on [[ActiveX]] or [[Java (software platform)|Java]].

====Whitelisting====

Some KVM chipsets or manufacturers require the "whitelisting" or authority to connect to be implicitly enabled. Without the whitelist addition, the device will not work. This is by design and required to connect non-standard USB devices to KVM extenders. This is completed by noting the device's ID (usually copied from the Device manager in Windows), or documentation from the manufacturer of the USB device.

Generally all HID or consumer grade USB peripherals are exempt, but more exotic devices like tablets, or digitisers or USB toggles require manual addition to the white list table of the KVM.

====Implementation====

In comparison to conventional methods of remote administration (for example [[Out-of-band management|in-band]] [[Virtual Network Computing]] or [[Terminal Services]]), a KVM switch has the advantage that it doesn't depend on a software component running on the remote computer, thus allowing remote interaction with base level [[BIOS]] settings and monitoring of the entire booting process before, during, and after the operating system loads. Modern KVM over IP appliances or switches typically use at least 128-bit data encryption securing the KVM configuration over a WAN or LAN (using [[Secure Sockets Layer|SSL]]).

KVM over IP extenders can be implemented in different ways. With regards to video, [[Peripheral Component Interconnect|PCI]] KVM over IP cards use a form of [[screen scraping]] where the PCI [[bus master]] KVM over IP card would access and copy out the screen directly from the graphics memory buffer, and as a result it must know which graphics chip it is working with, and what graphics mode this chip is currently in so that the contents of the buffer can be interpreted correctly as picture data. Newer techniques in [[OPMA]] management subsystem cards and other implementations get the video data directly using the [[Digital Visual Interface|DVI]] bus. Implementations can emulate either [[PS/2 connector|PS/2]] or [[USB]] based keyboards and mice. An embedded [[Virtual Network Computing|VNC]] server is typically used for the video protocol in [[Intelligent Platform Management Interface|IPMI]] and [[Intel Active Management Technology|Intel AMT]] implementations.