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Is your network ready for the KVMoIP revolution?Brian Andrews of Black Box Network Services explains the network requirements of the modern KVMoIP solution, and offers advice on what to look for when specifying switches.As the use of KVM technology has become widespread, the requirement to provide access to servers across the corporate network has grown. Initially KVM solutions used the physical infrastructure as their communications path, utilising the raw copper or fibre cabling to provide point to point extension. However, as existing infrastructures have grown to support new types of IP based access - including VOIP phones, media players, and wireless devices - there has been an increasing demand for access to servers over this same IP infrastructure – KVMoIP. But not every network is ready to provide the kind of low latency, high bandwidth connection that is required for real time KVMoIP. So what needs to be implemented to ensure a successful transition from non-IP to IP based solutions? Two scenarios for KVMoIP The first thing to understand is that there are two main scenarios for KVMoIP. The first, traditional requirement is for external access over low speed connections. This is to allow engineers to be able to remotely access servers for maintenance and problem solving, minimising site visits, and allowing engineers to carry out emergency tasks quickly and effectively. KVMoIP solutions for this use case are designed for high latency, low bandwidth connections, and compress the video as much as possible to reduce bandwidth demands. If they save the time and cost associated with site visits by providing all the access required, albeit with low video quality, then they have achieved their goals. They are not intended as a full time remote access solution. The more recent use case for KVMoIP centers around the concept of providing an excellent user experience by displaying excellent quality video through the use of high bandwidth links – typically at 1Gbps per connection – running over low latency connections such as a dedicated gigabit Ethernet network. Video is compressed using the latest lossless techniques and often a communication path for interfaces such as USB2.0 is also included. When using KVMoIP in an extension only mode, there are no real major issues for the Ethernet switches and routers to be concerned with. As long as the switches can handle multiple streams running at full gigabit speeds across their backplane, all is well. A bandwidth hungry solution But when switching between multiple sources, or broadcasting out to several users simultaneously, closer attention needs to be paid to ensure a successful roll out. It is possible to run multiple unicast sessions, where each user has their own session set up, but because each individual user has their own session, the bandwidth required is multiplied by the number of users who wish to join. This is a bandwidth hungry solution and will cause many issues including bad bandwidth utilisation, increased host and routing power consumption and much higher latencies. A bandwidth efficient solution Providing a bandwidth efficient solution requires the use of multicast traffic which reduces the session bandwidth required to a single session, which users can then join or leave as required. Layer 3 switches are typically required for this task, supporting IGMP Version 2 Snooping and Querying. Some Layer 2 switches provide this function as well, and the term Layer 2+ has been introduced to reflect their additional functionality over and above typical Layer 2 switches. These switches only provide the multicast session to those users who have requested to join. They filter out the traffic from all users not requesting to join and therefore free up a lot of bandwidth. This implementation requires only a single session over a single data stream, rather than one per user.
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