What are the limitations for remote KVM? Does compression affect KVM over IP performance?
Although remote keyboard, video display and mouse (KVM) is a well-established technology at this point, there are some potential issues including connectivity, bandwidth and latency, security and overall performance.
In order to access a remote server over IP, there must be appropriate connectivity. This isn't such a problem in a LAN setting, but can be far more problematic across the Internet, where multiple service providers and LANs can be involved. A disruption at any point across the network -- such as an ISP suffering a service outage -- can prevent administrators from accessing their target systems. This can pose problems for support response times and potentially exacerbate problems in remote production servers; you can't fix them if you can't access them.
Another consideration is the impact of bandwidth and latency. A lightly used network might have no problem at all accessing a remote server using KVM over IP, while a heavily utilized network with time-sensitive traffic -- such as storage or VoIP -- might cause delays in remote KVM traffic. The resulting pauses and hesitation make the KVM hard to use. In some cases, remote servers are configured to use a dedicated management network rather than the common user and data network. Substantial geographic distances between the KVM and servers might also cause latency and annoying interface hesitation. Tactics such as reducing video quality, increasing bandwidth and relying on a dedicated management network can alleviate some of these problems.
Security cannot be overlooked. Data transferred by KVM over IP should always be encrypted. This prevents keyboard, mouse and video data from being intercepted and viewed -- potentially revealing passwords and other sensitive configuration options for the servers and their applications. Encryption is commonly used to protect KVM over IP data. When Web browsers are used to make the KVM connection, the encryption is usually provided using Secure Sockets Layer (SSL). Always verify remote KVM security before going live.
Finally, consider how compression and connection activity affects remote KVM performance. For example, high levels of video compression and large numbers of simultaneous connections can impair KVM over IP. It may be better to reduce video quality and ease compression to speed up video performance and reduce the total number of KVM over IP connections trying to exchange data simultaneously over the network.
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