If an entry for the source address is not available in the CAM table, it creates a new entry for that source. When processing an incoming frame, the switch checks the source MAC address of the frame in the CAM table. The MAC address learning process is relatively simple. All five switches not only learn all MAC addresses automatically but also make their correct entries in the CAM table. Thanks to the dynamic learning feature, you do not need to type any MAC address. Furthermore, if you relocate any device, then you have to update all related entries manually. For example, if you have 1000 devices connected through the 5 switches, then you have to make 5000 (1000 * 5) entries. These MAC addresses are automatically copied back into the CAM table at the startup when we restart the switch.Īdding MAC addresses in the CAM table is a very tedious and boring task. When we copy the running-configuration into the NVRAM, any MAC addresses which we add statically are also saved in the NVRAM. At startup, the switch copies the running-configuration saved in the NVRAM to the RAM. Any contents stored in the NVRAM remains available after the restart. To preserve the changes which we make in the running-configuration, the switch allows us to copy the running-configuration into the NVRAM. All contents stored in the RAM are wiped out automatically when we turn off the switch. The switch stores the CAM table in the RAM. In the dynamic option, the switch learns and adds the MAC addresses in the CAM table automatically. In the static option, we have to add the MAC addresses in the CAM table manually. Static V/s Dynamic configurationĪ switch can learn MAC address in two ways statically or dynamically. In the below section, we will understand how the switch learns and stores MAC addresses in the CAM table.
No matter what name you use to refer this table, it is used to store the MAC addresses of the connected devices. Nowadays, the CAM table is also known as the MAC forward table, or MAC filter table, or MAC address table, or switching table, or bridging table. The switches use RAM to store this table, but the trend to use the term CAM table remains to continue. Gradually, the bridges were replaced by the switches. To refer the table that stores in the CAM memory, the term CAM table was used. In old days of switching, when the bridges were used to be in the networking, a special form of high-speed memory, known as the content addressable memory or CAM memory, was used to facilitate the switching function. The switch stores the learned MAC addresses in a table that is known as the CAM table.
To make accurate forwarding and filtering decisions, the switch learns and stores the MAC addresses of all connected devices.
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