Saturday, October 3, 2009

Virtual servers

Convergence blurs the traditional line between the servers and the network. In order to maintain visibility and control, it is important to identify and monitor all the switches in the converged network. Previously, the importance of maintaining visibility while migrating to blade servers was discussed. Maintaining visibility while virtualizing servers creates similar challenges.

The diagram shows the migration of multiple stand-alone servers connected to a stand-alone switch to a single server running multiple virtual machines. In this transition, where did the switch go? Popular virtual server systems such as VMWare® and Xen® make use of software "virtual switches" to connect virtual machines together and to the network. Using sFlow to monitor the virtual switches ensures that the benefits of virtualization can be realized without losing the visibility into network traffic that is essential for network troubleshooting, traffic accounting and security.

Currently, software probes are required to monitor virtual switches. However, the approach of using software probes has similar limitations to using probes to monitor physical switches: probes have limited performance and the installation and configuration of probes adds complexity to the task of managing the network. To provide a truly scalable solution, visibility must be an integral part of every switch, physical or virtual. The need for visibility is evident to virtualization vendors and virtual switches will soon be available with built-in sFlow support.

Multi-vendor support for sFlow ensures that all the layers in the network, from virtual switches, blade switches, top of rack switches and core switches can be monitored using a single technology. Convergence to high speed switched Ethernet unifies LAN and SAN connectivity and convergence to sFlow for traffic monitoring provides the network-wide visibility needed manage and control the unified network.

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