Port mirroring

Also called SPAN (Switched Port Analysis if on Cisco systems), consists in a switch port sending information about the packets on a network off to another switch port in order to achieve ongoing traffic monitoring to avoid unwanted intrusions. Network engineers or administrators use port mirroring to analyze and debug data or diagnose errors on a network. It helps administrators keep a close eye on network performance and alerts them when problems occur. It can be used to mirror either inbound or outbound traffic (or both) on single or multiple interfaces. Port mirroring allows for accurate network performance measurement of the by means of a protocol analyser on the port receiving the mirrored data, thus analysing each segment f data separately.