KVM switches were originally designed to allow a single operator to control multiple computers. This was done by switching between the human interface devices (i.e. the Keyboard, the Video screen and the Mouse) of each server in the computer room. This switching task evolved over time from patch panel through mechanical switch to digital KVM switches.

KVM switches allow you to access multiple computers through a single switch. From a single console (i.e Keyboard, Video and Mouse) you can connect to an entire rack or room full of computers - regardless of what operating systems the computers are running, and without loading any custom software on to computers. Today's digital KVM switches connect to the ports on each server being managed, and then digitize the signals. Proprietary techniques are used to compress, multiplex and then extend the original video between 100 and 1000 feet from the computer (over copper). However digital KVM solutions are limited in distance. Some vendors use fiber extenders to extend the reach to one mile, but they are still distance limited. To overcome distance limitations, a suite of proprietary video transfer over TCP/IP technologies were developed - and KVM over IP was born.

KVM over IP enables computers in local data centers to be operated and managed over the local network. So system administrators can centrally connect to all their local servers on the local IP network. The fact is that KVM over IP is a good solution for centralised local connection. It extends the distances, and reduces the physical cabling chaos that comes with legacy analog or digital KVM installations. So KVM over IP is good, but there's a better virtual KVM alternate with software solutions like VNC and RDP which are integrated freely into today's standard operating system platform. These software solutions deliver almost all the features of KVM over IP - without any of the cabling complexities of KVM. Also they were designed for both local and remote operation, and they scale.

The KVM over IP fantasy

A popular KVM over IP fantasy is that this technology enables "system administrators to view remote video screens and use their local keyboard and mouse as if they were connected locally - so servers and appliances across widely distributed networks can be monitored and managed real time, from a central remote site."

This fantasy flies in face of the simple fact that KVM over IP transfers a video data stream over the network. It creates far more traffic than alternates like RDP, and delivers a quality and performance level that may be adequate as a disaster recovery tool, but certainly is not appropriate for remote operational access. Other obvious KVM over IP weaknesses are the fact that: it just doesn’t scale, as the video processing and cryptography overload KVM over IP appliance processor and most products allow only a few simultaneous users it has limited intelligence, as it transmits raw screen bit map images (not data) so alerting and alarm monitoring are not possible it can only manage screen/keyboard devices so is of no use with network appliances etc it delivers poor quality video, as KVM is built on video analogue to digital conversion which by design is susceptible to screen jitter and noise it's proprietary, so there's no interoperability between different vendors' products

The future of KVM over IP

KVM over IP does enable administrators to control servers at the BIOS level and to warm restart computers (e.g. Ctl Alt Del). This is a simple function that KVM over IP can deliver over the Internet, so basic KVM over IP capabilities are being embedded in standard servers. All next-generation servers now ship with a service processor, separate from the main processor, which provides remote systems management capabilities. At the entry level these service processors provide power control and sensor readings. The more advanced units also offer an out of band access path for server configuration and for remote video monitoring and keyboard and mouse control. Offerings like HP's Lights-Out and Dell's DRAC have embedded KVM over IP capabilities so administrators have a remote keyboard, mouse and monitor for emergency situations regardless of the server's operating condition. The goal of these embedded remote control capabilities is to reduce the need to physically visit or find onsite assistance to support servers for troubleshooting, deployment and updating.

Remote Control Features & Benefits

Console Server

KVM over IP

Remote access to applications and services
Desktop graphical screen presentation
Transfer text data and files
Upgrade and reconfigure operating systems
Bios-level access to your servers
Monitor data transfer to trigger alarms
Warm reboot ability
Remote power cycling - hard reboot
Provides out-of-band access
Dial-in (with dial-back validation) access
Encryption of data over public networks
Username and password protection
Authenticates users with industry-standards (RADIUS TACACS)
Collaboration - multiple users sharing concurrent sessions
User level assigned access permissions
Provides logging of user access and system activity
Manages wide range of systems (Windows, Linux, UNIX, Solaris, AIX, HPUX, Mac)
Controls network appliances (firewalls, routers)
No additional software must be installed on servers
Cost effective remote control

The Integrated Remote Management Solution

A KVM over IP solution works well as a remote management tool down at the Windows EMS and BIOS levels, however this is of limited utility particularly as it cannot interface at all with other key infrastructure like power switches, routers and firewalls. A IM4200/CM4000 solution couples with the KVM capabilities embedded in service processors in the newer servers and delivers the best of all worlds. It delivers secure and robust Telnet access to the serial consoles; HTTP/UDP/IPMI access to the network consoles; and the VNC and Remote Desktop access delivers virtual KVM benefits. Also SDT and SDTConnector securely connect to the service processors, and deliver seamless access to the KVM embedded there.