After my on-site interview at Google, I decided to write a post about the MAC table and the ARP table.
What is the MAC table?
The MAC table (or CAM table) is the table which contains MAC addresses. A switch uses this table to switch frames to the right output interface.
This table is filled using the source MAC address of each frame which traverses the switch. If there is no entry in the MAC table for a destination MAC address, then the switch will flood the frame. The default aging time in the MAC table is 5 minutes.
What is the ARP table?
The ARP table is the table which contains the bindings MAC address - IP address. Each machine (which uses IP address to communicate) in the network has a ARP table. This table is filled by each ARP reply. If there is no entry in the ARP table for a destination IP address, then the machine will send a ARP request to determine the MAC address corresponding to the IP address. The default aging time in the ARP table is 4 hours.
Because the default aging time of these tables are different, it may create some problems.
1 comment:
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