Modular Video Distribution over KVM Networks

For a long time, it was popular to route or switch keyboard, video and mouse signals using retro rotary switches or KVM extenders in the form of passive cables. That was mainly because improvised KVM connections could save money. Those days are over, however, and a bustling market for modern KVM technology has developed in their place. All that’s left is the name; both the applications and the target group have changed completely.

Today, KVM extenders are typically used to send uncompressed high-resolution videos over long distances at speeds of 20Gbit/s or more. It’s still justified to talk about KVM, as in most cases both USB and control signals are sent together. As a result, today KVM switches can also be found in state-of-the-art conference and training rooms as fully digitised solutions which are able to split and flexibly output multiple input signals.

Combining KVM Extenders with Classic Network Matrices
IP-based systems are the main alternative to KVM extender solutions. However, they have the serious drawback of only providing a fraction of the bandwidth of a KVM solution, even in high-performance networks – in addition to being much more time-consuming to install and configure and being prone to delays. The new KVM extender series from Lindy now closes the gap. It makes it possible to combine and split proprietary extender signals while using conventional network switches. The transmitter of a KVM extender is linked to a computer or any other image source and routed via a Cat.6 Ethernet cable to a matrix switch, to which all of the receivers can be individually connected. Up to 48 transmitters and receivers can be interconnected in this way. In addition to a video-only signal, USB 2.0 and – depending on the model – audio and RS232 can also be transmitted.

To install a modular KVM network of this kind, all it takes is a high-performance matrix and the desired numbers of KVM transmitters and receivers. Everything is just as straightforward to install and hook up everything as with old-fashioned non-IP-based KVM extenders.

Example Applications
The example of a training room illustrates the benefits of a modular KVM extender solution. The PCs are normally installed in a separate room for security reasons and to reduce noise. A KVM transmitter links each of them to a matrix switch, and a receiver is installed at each workplace or desk in the training room, as well as at the teacher’s desk and at the projector.

At the press of a button, the teacher can duplicate any participant’s screen image and output it to her workstation or the projector. Conversely, it’s just as easy for her to switch her display through to the screens of all of the participants.

For redundancy, two additional computers with transmitters can be installed in the PC room and used from any workstation in the training room in case one of the others stops working or has been incorrectly configured.

Technical Background
The KVM network requires an isolated VLAN with a bandwidth of at least 1Gbit/s and Cat.6 shielding. Thanks to jumbo frames, lower overhead and minimal latency, data can be sent over a gigabit network at rates up to 4.95Gbit/s. So at Full HD, although it’s necessary to compress the signal, unlike a IP-only solutions there is no noticeable loss of quality and, best of all, no delay whatsoever.

The maximum resolution is 1920×1200 @60 Hz (WUXGA) with parallel transmission of USB 2.0, RS232 and audio (analogue stereo). HDCP is not supported.

Although technically speaking this is an Ethernet solution, it’s important to avoid cables that exceed a certain maximum length, although this can vary quite a bit depending on the cable type. In copper-based networks, the limit is 130 metres and with multimode optical fibre it’s 500 metres. With single-mode fibre-optic cable, by contrast, there is practically no limit. Lengths up to 20km have been successfully tested. However, it is not possible to combine copper and fibre-optic extenders, even with a matrix inserted between them.

Models, Prices and Availability
Lindy offers three different KVM extenders, all of which can be used as KVM network components with the aid of a gigabit switch. Depending on the model, extra functions such as audio transmission or support for USB mass storage can be retrofitted as upgrades. To use the matrix functionality for KVM networks, it is also necessary to purchase an activation code.

The “130m Cat.6 DVI-D single-link & USB 2.0 KVM extender” has an HDMI input and an HDMI loop output with adaptor for DVI. The carrier medium is a Cat.6 network cable. The USB mass storage functionality can be added by purchasing a software upgrade. Audio is not available. The transmitter costs €419.95, and the price of the receiver starts at €414.95. With the mass storage option, it increases to €764.90. The transmitter automatically obtains the mass storage option from the receiver. (The article number for the basic transmitter version is 39200 and for the basic receiver version 39201.)

The “130m Cat.6 DVI-D single-link, USB 2.0 (optional audio or RS232) KVM extender” features a DVI-D input and a DVI-D loop output. The carrier medium is a Cat.6 network cable. The transmitter costs €574.95. The price of the basic receiver version is €569.95, which increases to €919.90 with the mass storage option, to €709.90 with audio support and to €1,053.84 with both. The receiver upgrades are automatically also applied to the transmitter. (The article number for the basic transmitter version is 39210 and for the basic receiver version 39211.)

The “500m fibre-optic DVI-D single-link & USB 2.0 KVM extender” has a DVI-D input and a DVI-D loop output. The carrier medium is a multimode fibre-optic cable. The transmitter costs €584.95, and the the price of the basic receiver version is €579.95. (The article number for the basic transmitter version is 39240 and for the basic receiver version 39241.)

The prices given do not include the statutory value-added tax.