What is MAC Address Table ?

MAC stands for Media Access Control it is a physical address that uniquely identifies a device and hardware manufacturer on a network. Most commonly used in  (IEEE 802) networking technologies, like Ethernet, WiFi, and Bluetooth technology.

A mac address is globally unique so suppose two devices are on the internet they can not have the same MAC address. It works on the Data link layer of the OSI model. It is also known as the Ethernet address 6 bytes or 48 bits in length typically written in hexadecimal format.

A MAC address is generally assigned to the Network Interface Card of every device that is connected to the internet.

Why is MAC Address Unique for All Devices?

If a network has a topology of two or more devices with the same MAC address, it will not work. This is crucial when several large devices are connected within a single organization.

Example:

In an Organization, two devices, A and B, are connected through a router or a switch. The MAC addresses of the devices should be  00000ABB98FC and 00000ABB58FC, respectively.

A MAC address can be expressed in 3 general formats:

• Hyphen-hexadecimal Notation
• Colon-Hexadecimal Notation
• Period-Separated Hexadecimal Notation

Command to Find the MAC Address in a Device

Command For Linux

ifconfig -a

ip link list

ip address show

Command For Windows OS

ipconfig /all

Command For MacOS

TCP/IP Control Panel

MAC Address Table

The switch maintains an address table called the MAC address table in order to efficiently switch frames between interfaces. So basically a switch stores information about the other (Ethernet interfaces) to which it is connected on a network. When a switch receives a frame, it associates the MAC address of the sending device with the switch port on which it was received.

Need of MAC Address Table

The MAC address table is a way to map each and every port to a MAC address. The MAC address table consists of two types of entries. 

• Static Entries: Static entries have high priority than dynamic entries and remain active they can be changed or removed by the switch administrator as they are manually added by the switch administrator.

• Dynamic Entries: Dynamic entries are added to the table automatically with a process called MAC learning here the switch fetches the source MAC address of each Ethernet frame received on the port. Dynamic entries are automated they are automatically deleted.

Steps to Check MAC Address Table

• Click Start or click in the search box and type cmd.

• Then click on the command prompt.
• After that type arp -a on prompt.