| KVM is an acronym for
keyboard, video (monitor) and mouse, and is
otherwise called a PC switch or electronic
switch. However, this different from the conventional
data switch. The main function of KVM is to
control, switch and manage many PCs via a
single keyboard, monitor and mouse. According
to the basic PC function design, as the PC
is starting up, the operating system will
automatically detect the signals of the keyboard
and mouse. After confirmation of connectivity,
the screen then enters the start up page.
As a result, a single PC (CPU/Server) naturally
complements the start up operations of the
keyboard and mouse. If you need to control
multiple PCs, then you need to purchase several
sets of keyboard, mouse and monitor. However,
this is not the most effective way of management
as not only is it space-consuming, but also
costly, and keeping a row of large CRT monitors
may be problematic. Thus, the KVM was "born"
under the demands of saving space, costs and
increasing management efficiency. When purchasing
a KVM, the choice is often made based on the
number of PCs that you need to control. Low
port number KVMs are convenient to use, without
the installation of extra software, and can
be easily managed using hot keys or switch
keys. Some of these low port number KVMs do
not need an exteral power supply. Due to environmental
needs, multiple ports, high-level KVM switches
are designed to 1U or 2U in size and can be
installed on the server rack. These KVM switches
can use the Internet to manage power supply
and control the start up or shut down of PCs.
 The
main function of a KVM is to use one of
keyboard, monitor and mouse to start multiple
PCs, so it is important to simulate the
keyboard and mouse signals to each PC and
not influence the CPU operations during
switching. Other important factors to consider
when buying a KVM is the stability of the
monitor resolution, whether or not it supports
multiple platforms, and the compatibility
of operating systems with different branded
keyboards and mice. Every KVM Switch has
a maximum number of PC connections. A single
KVM switch can provide as few as two CPU
ports, while a multiple KVM switch installation
can offer more than 4000 CPU ports. As the
number of connected PCs increase, the technology
needs are higher (for example, signal identification)
and the different ways of management increase
(for example, remote control, multiple segmentation,
high-level security, etc.) in order to meet
the management demands of different environments.
Currently, the remote control solutions
use both hardware (KVM) and software (for
example, PC Anywhere, VNC, OpenSSH, Microsoft
Telnet Service, etc.). To understand the
comparison between hardware and software,
please refer to the Remote Control Solution
column.
Previously, KVM has been used in server
rooms and data information centers. An average-sized
room will contain 16 to 32 servers, whereas
a large room may contain over 100 servers.
As the trend is for PC prices to become
increasingly lower, many people are able
to purchase a second PC or laptop, making
KVM necessary for the average consumer.
Advancements in technology, new specifications,
innovative concepts and new applications
have pushed KVM to evolve (for example,
KVM + Peripheral / KVMP¡BKVM + Fast
Ethernet / KVME, Wireless KVM, KVM on the
Net, etc.). These new KVM are increasingly
popular in the consumer market and as digital
appliances become more mainstream, KVM's
multi-faceted development can cater to this
market and create new concepts that may
not have been previously possible.
Some basic terminology for KVM Switch specifications
include:
1. Ports
The number of ports is indicative of the
number of PCs that can connect to the KVM.
For example, for an 8 Port KVM Switch, a
single keyboard, monitor and mouse can control
up to 8 PCs. Currently, the most common
number of ports for KVM is 2 Port, 4 Port,
8 Port, 16 Port and 32 Port. When the number
of PCs surpasses thirty-two, cascading or
daisy chaining the KVMs is then used to
connect to the PCs. In order to more conveniently
control and run many PCs, some KVM have
various functions to assist in management.
For example, using functions such as hot
keys, OSD, broadcasting, etc. Some innovative
KVM companies also develop proprietary embedded
core logic chip in order to increase operational
stability and the efficiency of the signal
execution.
Note: Please
refer to the high-end KVM feature article
to find out more about connectivity.
2. Console
This term refers to the control that is
used to manage the keyboard, monitor and
mouse of the PC. Normally, a console has
three different ports for the keyboard,
mouse and monitor. The specifications for
the keyboard and mouse connector are USB
and PS/2, whereas the specifications for
the monitor are DVI and HDB 15.
Note: Console
KVM that support audio have ports for the
microphone and speakers. KVM that are specifically
used for SUN and MAC have different ports.
3. CPU
This term indicates the connected PC. A
single CPU port on a KVM has three different
signal ports (keyboard, mouse and monitor)
to connect with the ports on the PC. In
order to save on the BOM and to increase
the convenience of installation, some companies
manufacture their own proprietary cables,
combining the afore mentioned three cables
into one. This not only can shorten the
length of the KVM appearance, but also simplify
the desktop space. Although proprietary
cables have many advantages, however it
is also easily influenced by other signals.
It is recommended that a professional KVM
brand be chosen to minimize these problems.
Note: The
KVM that supports audio has ports for the
microphone and speakers on the CPU port.
KVM's categories can be divided as follows:
small office and home office (SOHO); small
and medium-sized business (SMB); and large,
high-end global enterprise-level KVM. Many
KVM companies then further divide high-end
KVM to remote-controlled high-end KVM and
nearby-controlled high-end KVM. For a further
explanations of the different types of KVMs,
please visit the home page.
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