If the probe is to be used to monitor SPAN/Mirror traffic, then a Tigon-based Gigabit Ethernet card (and PCI slot to install it) is required for each interface being monitored. 

Supported cards include the 3Com 3C985  and NetGear GA620. To monitor 100Mbit Mirror/SPAN ports you can use the copper versions of these cards since they support 10/100/1000Mbit operation. 

Note: Tigon-based cards are required so that packet processing firmware can be downloaded onto the the card to provide wire-speed operation. If other cards are used then all packets will be handled by the PC processor which may become overloaded during periods of heavy traffic.