Abstract: A capture buffer stores data frames captured from a network which includes a data storage region for storing content data of the or each data frame received from the network, and for storing a descriptor associated with the or each data frame received from the network. The invention further includes an auxiliary storage region for storing an indicator of a property of a frame.

Abstract: A network monitor that taps data from a network link has first and second interfaces that allow the network monitor to be connected in-line in the network link between two network devices. The monitor has first and second programmable logic devices. The programmable logic devices are arranged to receive parallel data output by the interfaces and to process said data for network analysis purposes. Each programmable logic device is controllable so as to selectively pass a copy of the received parallel data to the other programmable logic device so that the network monitor can operate in in-line mode and not to pass a copy of the received parallel data to the other programmable logic device so that the network monitor can operate in end station mode.