MAC Address (Media Access Control Address) is a network address that is implemented in the data-link layer in the OSI seven layer model, which represents a particular node in the network. In an Ethernet-based network, the MAC address is a unique address which has a long 48-bit (6 bytes) which identifies a computer, the interface in a router, or other nodes in the network. MAC Address is also often referred to as the Ethernet address, physical address or hardware address.
MAC Address allows the devices in the network to communicate between each other. For example, in an Ethernet-based network, each header in the Ethernet frame contains information about the MAC address of the computer resources (source) and the MAC address of the destination machine (destination). Some devices, such as bridges and Layer-2 switch will see the MAC address information from the source computer from every frame it receives and uses this MAC address information to create a "routing table" internal dynamic. These devices may then use the newly created table to forward frames that it receives into a port or a specific network segment in which the computer or node that has a destination MAC address is located.
In a computer, the MAC address assigned to a network card (network interface card / NIC) that is used to connect computers to the network concerned. MAC Address generally not be changed because it has been incorporated into the ROM. Some network cards provide a utility that allows users to change MAC address, although this is not recommended. If a network has two network cards that have the same MAC address, there will be conflicts and address of the computer can not communicate between each other. Some network cards, such as Token Ring card requires users to set the MAC address (not included in the ROM), before it can be used.
MAC addresses must be unique indeed, and for that reason, the Institute of Electrical and Electronics Engineers (IEEE) to allocate blocks in MAC addresses. The first 24 bits represent the MAC address of anyone making a card, and the remaining 24 bits represent the card number. Each group of 24 bits can be represented by using six-digit hexadecimal numbers, making a total of 12-digit hexadecimal number that represents the entire MAC address. Here is a table of several popular network card manufacturer and identification number in the MAC Address.
MAC Address allows the devices in the network to communicate between each other. For example, in an Ethernet-based network, each header in the Ethernet frame contains information about the MAC address of the computer resources (source) and the MAC address of the destination machine (destination). Some devices, such as bridges and Layer-2 switch will see the MAC address information from the source computer from every frame it receives and uses this MAC address information to create a "routing table" internal dynamic. These devices may then use the newly created table to forward frames that it receives into a port or a specific network segment in which the computer or node that has a destination MAC address is located.
In a computer, the MAC address assigned to a network card (network interface card / NIC) that is used to connect computers to the network concerned. MAC Address generally not be changed because it has been incorporated into the ROM. Some network cards provide a utility that allows users to change MAC address, although this is not recommended. If a network has two network cards that have the same MAC address, there will be conflicts and address of the computer can not communicate between each other. Some network cards, such as Token Ring card requires users to set the MAC address (not included in the ROM), before it can be used.
MAC addresses must be unique indeed, and for that reason, the Institute of Electrical and Electronics Engineers (IEEE) to allocate blocks in MAC addresses. The first 24 bits represent the MAC address of anyone making a card, and the remaining 24 bits represent the card number. Each group of 24 bits can be represented by using six-digit hexadecimal numbers, making a total of 12-digit hexadecimal number that represents the entire MAC address. Here is a table of several popular network card manufacturer and identification number in the MAC Address.
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