What Is a Cam Table?

A CAM (Content Addressable Memory) table is a component critical to the operation of an Ethernet networking switch. Ethernet switches connect multiple computers on a single network, in much the same way that hubs or other networking devices might. Unlike other networking devices, however, a switch contains a CAM table. The CAM table allows information routed through the switch to be addressed to a single computer on the network, rather than to all networked computers. This increases the specificity of information traveling through the network, at the cost of an increase in vulnerability to network system hacking attempts.

It's useful to think of a CAM table as a middleman, or as a traffic controller. It sits between the connected computers and all of the data moving through the network, directing the information as necessary to specific addressees. Without a CAM table, any information broadcast through the network switch would be sent simultaneously to each and every computer connected to the network. On many types of networks, this would present a serious privacy concern; imagine a banking network where each terminal had access to every bit of information flooding through the system: individuals' passwords and account information would be visible to all users. With the CAM table in place, data travels exclusively to its intended addressee's computer, obviating these privacy concerns./p>

CAM tables function using the Media Access Control (MAC) addresses of computers connected to the network. Think of these like post office box numbers. When information is sent along the network, it comes with a specific MAC address in mind. The CAM table takes the information, sorts it via MAC number, and ships it off to the intended computer.

Although CAM tables are useful for keeping data private within networks, the presence of a CAM table can increase the threat of network vulnerability to outside attacks. Hackers exploit the limited memory capacity of CAM tables in order to expose and intercept information moving across the network. Networks that employ CAM tables must be vigilant about this threat.

CAM tables can only store a limited number of addresses for specific MAC ports. Hackers attack the network by flooding the CAM tables with excessive MAC address information. Once the table overflows with data, it begins acting as a hub: disregarding privacy and sending data to every port simultaneously. Once this occurs, hackers can intercept the data across the network; it becomes visible to all connected computers. In addition to compromising the data on the network, this also impairs network performance, slowing the network to a crawl until the issue is resolved.