1. What Does Mac Address Stand For
2. What Does Bia Stand For Mac Address

Each network-compatible device has at least one unique hardware ID – the media access control address (in short: MAC address). What this is all about and how you can find or rewrite the MAC address is explained below.

1. What is a MAC address?
2. Finding out your MAC address: a how-to guide
3. Assigning the MAC address using software

What does MAC (ADDRESS) stand for? MAC (ADDRESS) stands for 'Media Access Control Address'. Q: A: How to abbreviate 'Media Access Control Address'? 'Media Access Control Address' can be abbreviated as MAC (ADDRESS). Q: A: What is the meaning of MAC (ADDRESS) abbreviation? The meaning of MAC (ADDRESS) abbreviation is 'Media Access Control. MAC ID (Media Access Control) is a unique digital number assigned to each computer on the network, more precisely not to a computer, but to a network card. The MAC address is registered on the network card when it is created in the factory.

What is a MAC address?

MAC address is a unique identifier for a physical network interface. MAC stands for Media Access Control, and are used in ethernet networks. To be able to send traffic on an ethernet network, you must know the MAC address of the destination. This can be achieved using ARP in IPv4 networks. In other words, the similar IP Addresses may indicate that a computer is close. The following example illustrates what an (IP v4) IP Address may look like: 120.40.193.57; MAC Address. The Media Access Control (MAC) Address is used to identify Ethernet network cards or simply PCs that have built-in Ethernet. In this case, a system does not send the addressed adapter’s real network hardware address in network communication, but instead a user-defined MAC address. Assigning an MAC address in Windows With Windows, you can overwrite the MAC address through the device manager if the network adapter’s device driver supports this function.

Each device that is integrated into a computer network requires a network adaptor. This adapter receives a worldwide unique identification number from the manufacturer: the MAC address. This enables devices like desktop computers, tablets, or mobile phones to be identified in the network and addressed as required. If a device has several network adapters (for example, for several LAN connections or different communication standards like Ethernet, WiFi, FDDI, Bluetooth, or Token Ring), a different address is available for each standard.

The MAC address (short for media access control address) is the worldwide unique hardware address of a single network adapter. The physical address is used to identify a device in computer networks.

Since MAC addresses are assigned directly by the hardware manufacturer, they are also referred to as hardware addresses. With Microsoft Windows, the MAC address is referred to as the physical address. Apple uses the terms Ethernet ID, Airport ID, or WiFi address, depending on the communication standard. The term device address, on the other hand, is fuzzy, since a device can have several network adapters and therefore different MAC addresses.

The MAC address in practice

Conflicting MAC addresses are a basic requirement for error-free network communication.

Data transmission in computer networks is a complex communication process in which different requirements including reliability, security, and efficiency must be met. This can be illustrated using the OSI models (abbreviation for open systems interconnection) – a reference model developed by the ISO (International Organization for Standardization) that maps network communication to 7 layers. During data transmission, each layer of the OSI model is run through on both the sender and receiver sides.

MAC addresses are used on the backup layer (layer 2) of the OSI model – actually, the media access controlsublayer introduced by the Institute of Electrical and Electronics Engineers (IEEE).

In the extension of the OSI model designed by the IEEE, the backup layer (layer 2) is divided into the sublayers media access control (2a) and logical link control (2b).

The backup layer is located between the bit transfer layer (layer 1) and the switching layer (layer 3). While the bit transmission layer provides protocols and tools responsible for maintaining the physical connection, protocols on the backup layer control how different systems share the available transmission medium. Secure system connections are abstracted from the physical connection. The actual transmission of data packets takes place at the switching level via IP.

For example, if you want to send an IP packet over Ethernet, your computer transmits a data frame that is addressed to the target computer’s MAC address on the backup layer, according to the OSI model.

If the target computer is not in the local network, a router is addressed and instructed to forward it to the internet. Routers integrated into a social network also have a unique MAC address.

An Ethernet data frame contains information that is read out at different levels of the OSI model.

Data frames in IPv4 networks contain the following components:

• Destination address (destination computer MAC address)
• Source address (sender’s MAC address)
• Control information for data flow control
• User data (the data packet that needs to be transmitted later on the switching layer)
• Checksums that ensure data integrity

A target computer that receives a data frame first reads it on the backup layer and compares the target address of the frame with its own MAC address. If the addresses match, the target computer starts interpreting the frame at the next higher level.

Network devices that are only used to forward data packets (repeaters) or manage parts of the network (bridges and switches) usually do not actively participate in network communication and so do not require their own MAC addresses.

To link the address assignment on the backup layer with the address assignment on the switching layer, the address resolution protocol (ARP) is used in IPv4 networks. Each computer in the local network maintains an ARP table whereby IP addresses are assigned to MAC addresses.

ARP is vulnerable to an attack pattern called ARP spoofing. The danger of ARP spoofing and the countermeasures you can take are discussed in the article above.

The new internet protocol standard IPv6 uses the neighbor discovery protocol (NDP).

MAC address syntax

MAC addresses in LAN or WLAN networks consist of 6 bytes (48 bits) and are written in hexadecimal notation. The use of separators such as hyphens or colons between two bytes increases readability.

The following example shows the MAC address of a desktop computer in binary and hexadecimal format:

In our example, we use canonical representation of the bit sequence. This corresponds to the order in which MAC addresses are transmitted in Ethernet. Other communication standards like Token Ring provide for bit-reversed transmission, starting with the most significant bit.

The bit sequence of each MAC address is divided into 4 areas, each of which encodes different information.

• Bit 1 (receiver): The first bit of the MAC address specifies whether it is an individual or group address. This bit is called I/G (short for individual/group). If I/G = 0, it is a unicast address for a single network adapter. Multicast addresses are identified by I/G = 1 and are addressed to several receivers.
• Bit 2 (registry): The second bit of the MAC address indicates whether it is an address with global validity (universal) or whether the address has been assigned locally (local). The bit is called U/L. If U/L = 0, the address is valid worldwide as a universally administered address (UAA). Addresses that are only locally unique are called locally administered address (LAA) and are marked with U/L = 1.
• Bit 3–24 (manufacturer identification): Bits 3 to 24 encode an identifier (organizationally unique identifier, OUI), which is assigned exclusively to hardware manufacturers by IEEE. The assignment of OUIs is usually public and can be determined via databases. A corresponding service is available, for example, on aruljohn.com.
• Bit 25-48 (network adapter identifier): Bits 25 to 48 provide device manufacturers with 24 bits for assigning a unique hardware identifier (organizationally unique address, OUA). This means that 2²⁴ (= 16.777.216) unique OUAs can be assigned per OUI.

Table: Subareas of an MAC address

Finding out your MAC address: a how-to guide

What Does Mac Address Stand For

MAC addresses can be queried through the terminal in all modern operating systems with little effort – both on the local system and remotely in the network. The following table shows the corresponding command line commands for the most common operating systems.

Table: MAC address read out

On mobile devices, you can display the MAC address in the settings.

Table: Get MAC addresses on mobile devices

Read MAC address locally

If you want to read out the MAC addresses of the LAN and WiFi adapters on your Windows computer, proceed as follows if using Windows 10.

Step 1: Open the terminal of your operating system. For example, use the keyboard shortcuts [Windows button]+[R]. Then enter “cmd” in the window “Run” and confirm with “OK.”

Step 2: From Windows 2000 onwards you can use the command line utility ipconfig with the “/all” option to get the MAC address of all network adapters on your Windows computer.

Alternatively get the MAC address with the command “getmac /v”

Step 3: With Windows, the MAC address is displayed under “physical address.”

Accessing your MAC address remotely

Thanks to ARP, in IPv4 networks it is possible to determine other devices’ MAC addresses in the same local network. With Windows and most unixoid operating systems, use the command line “arp” with the option to display you system’s ARP table in the terminal.

You will receive a terminal output according to the following scheme:

If you just want to read the MAC address of a specific network adapter remotely, use the command “arp –a” in a combination with the target adapter’s local IPv4 address.

Assigning the MAC address using software

MAC addresses are invariably assigned by device manufacturers and are “burned” into the network adapter chip on the hardware side. However, numerous operating systems offer the option to overwrite hardware addresses on the software side. This is referred to as spoofing. In this case, a system does not send the addressed adapter’s real network hardware address in network communication, but instead a user-defined MAC address.

Assigning an MAC address in Windows

With Windows, you can overwrite the MAC address through the device manager if the network adapter’s device driver supports this function.

Step 1: Open the network adapter settings. To do this, follow the click path: Start à Settings à Network and Internet à Ethernet à Change Adapter Options

Step 2: Right-click on the desired network adapter and select “Disable” in the context menu.

Step 3: Right-click on the desired network adapter and select “Properties” from the context menu. A pop-up window opens called “Network adapter properties.”

Step 4: Click on the “Configure” button in the pop-up window and select the “Locally Administered Address” property under “Advanced.” Enter your chosen software MAC address under “Value.”

Assign MAC address in unixoid operating systems

Unix derivatives such as Linux, macOS, Solaris, and the BSD operating systems support the assignment of MAC addresses through the terminal on the software side.

Table: Overwriting a MAC address

We illustrate the procedure using the most commonly used Unix derivative: Linux. If you want to change your network adapter’s MAC address, proceed as follows.

Step 1: Open the operating system terminal – for example, with the key combination [CTRL]+[ALT]+[T].

Step 2: Determine the name and current MAC address of the desired network adapter. To do this, enter the following command in the command line:

Note the hardware address assigned by the manufacturer in case you want to undo the change.

Step 3: Turn off the network adapter by entering the following command in the command line:

Enter the name of the network adapter determined through “ip link” for <Interface>.

Step 4: Overwrite the network address assigned by the manufacturer with one of the options specified in the table.

Enter the chosen MAC address instead of XX:XX:XX:XX:XX:XX

Step 5: Restart the network adapter. Use the following command line command:

To ensure that the selected network adapter is accessible at the MAC address you selected, re-read the network information with “ip link” (see step 1).

This tutorial explains the MAC (Media Access Control) address in detail. Learn what the MAC address is, how it is formed, and the types of MAC addresses (unicast, multicast, and broadcast).

In network, an address provides a unique identity to an end device. Unless an end device has a unique address, it can’t communicate with other devices in the network. A unique address enables an end device to send and receive data in the network.

In the LAN network, a unique address is the combination of two addresses; software address and hardware address.

Addressing in Networking Reference models

A networking reference model defines the standards, characteristics, definitions, and functionalities of the network. There are two popular networking models; the OSI Seven Layers model and the TCP/IP model.

In both models, the software address and hardware address are defined in the network layer and data link layer, respectively. In both models, the network layer and data link layer stand on the third and second positions, respectively. Because of this, both layers are also known as layer 3 and layer 2, respectively.

Software address

The software address is also known as the network layer address or layer 3 address. This address is manageable and configurable. Based on network requirements and layout, this address can be configured and assigned to an end device. Almost all modern LAN implementations use the IP protocol in the network layer. The IP protocol uses the term IP address to define the software address.

I have already explained IP addresses in the following tutorial.

In this tutorial, I will explain the hardware addresses in detail.

Hardware address

The hardware address is also known as the data link layer address or layer 2 address or MAC (Media Access Control) address. From these terms, the term MAC address is commonly used to refer to the hardware address. Unlike the IP address or software address, this address can’t be configured or managed. When you purchase a new NIC (Network Interface Card), or any device which has onboard NICs, it comes with a pre-configured MAC address.

A MAC address is 6 bytes (48 bits) long address in the binary numbers. MAC addresses are written in the hexadecimal format. The hexadecimal format uses the base-16 to refer to numbers. If we divide the total available length (48 bits) in binary numbers by the base (base-16) that is used to write a number in hexadecimal format, we get the total digits (12 = 48 ÷ 16) of that number in the hexadecimal format. Thus, if we write a 6 bytes (48bits) long binary MAC address in hexadecimal format, we get a 12 digits long hexadecimal number.

For convenience and easier readability, when writing a MAC address in hexadecimal format, extra space or periods or colons are added after every two or four digits. For example, you can write a MAC address in the following ways.

• Without any separator: - 00000ABB28FC
• Extra space after every two digits: - 00 00 0A BB 28 FC
• Extra space after every four digits: - 0000 0ABB 28FC
• Colon after every two digits: - 00:00:0A:BB:28:FC
• Colon after every four digits: - 0000:0ABB:28FC
• Period after every two digits: - 00.00.0A.BB.28.FC
• Period after every four digits: - 0000.0ABB.28FC

No matter which style you use to write the MAC address, or an application or networking software uses to display the MAC address, a MAC address is always processed in binary numbers only. NIC converts hexadecimal numbers of the MAC address in binary numbers before processing and using it.

Structure or format of the MAC address

As mentioned above, you can’t assign MAC address to a NIC or onboard NICs. When you purchase a new NIC or a device with onboard NICs, it arrives with a pre-configured MAC address or MAC addresses, respectively. Before we understand how manufacturers select MAC addresses for NICs, let’s briefly understand why a MAC should be unique in the LAN network.

If a LAN network has two or more NICs configured with the same MAC address then that network will not work. Let’s understand this with an example.

Suppose in a network three PCs; PC-A (11000ABB28FC), PC-B (00000ABB28FC) and PC-C (00000ABB28FC) are connected through a switch. NICs of PC-B and PC-C have the same MAC address 00000ABB28FC.

If PC-A sends a frame to the destination MAC address 00000ABB28FC, the switch fails to deliver this frame as it has two recipients of this frame.

The following image shows this example.

A LAN network does not work unless each device in the LAN network has a unique MAC address.

Now let's be back to our main question. How do manufacturers assign a unique MAC address to each NIC?

Before manufacturing NICs, every manufacturer obtains a universally unique 3-byte code, known as the organizationally unique identifier (OUI), from the IEEE. The IEEE is an international organization that regulates and maintains the namespace of MAC addresses.

After obtaining the OUI bytes, the manufacturer uses these OUI bytes at the beginning of the MAC address of all its NICs or on-board NIC devices. The manufacturer also assigns a unique hexadecimal value in the remaining bytes.

6 bytes MAC address = 3 bytes OUI number obtained from the IEEE + 3 bytes unique number assigned by the manufacturer

MAC addresses of all NICs or onboard NIC devices manufactured by the same manufacturer always start with the same 3-bytes OUI numbers. For example, suppose the IEEE assigns an OUI “0000AA” to the xyz company. Now the xyz company will use the OUI number 0000AA as the first 24 bits to build MAC addresses for its NICs or onboard NICs devices.

To keep each product separately from others, the manufacturer uses the remaining 3-bytes. Manufacturers are free to use any sequence or method on the remaining three bytes. For example, the xyz company can assign the MAC addresses to its NICs in the incremental order.

The following table extends this example and adds two more demo companies (ABC and JKL) in the example. It also shows MAC addresses of 5 NICs from each company.

What Does Bia Stand For Mac Address

Thus, this procedure ensures that no two NICs use the same MAC address in the universe.

Types of MAC address

There are three types of MAC address; unicast, multicast, and broadcast.

Unicast MAC address

Unicast MAC address represents a specific NIC or onboard NIC ports in the network. The inbuilt MAC address of a NIC is the unicast MAC address of that NIC.

Multicast MAC address

Multicast MAC address represents a group of devices (or NICs in Layer 2). The IEEE has reserved the OUI 01-00-5E (first 3-bytes or 24 bits) for the multicast MAC addresses. The remaining 24 bits are set by the network application or device that wants to send data in the group. A multicast MAC address always starts with the prefix 01-00-5E.

Broadcast MAC address

Broadcast MAC address represents all devices in the network. The IEEE has reserved the address FFFF.FFFF.FFFF as the broadcast MAC address. Any device that wants to send the data to all devices of the network, can use this address as the destination MAC address.

That’s all for this tutorial. If you like this tutorial, please don’t forget to share it with friends through your favorite social channel.