This includes workstations, servers, printers, mobile devices, and routers. Note: Ethernet NICs will also accept frames if the destination MAC address is a broadcast or a multicast group of which the host is a member.Īny device that is the source or destination of an Ethernet frame, will have an Ethernet NIC and therefore, a MAC address. If there is a match, it passes the frame up the OSI layers, where the de-encapsulation process takes place. If there is no match, the device discards the frame. When a NIC receives an Ethernet frame, it examines the destination MAC address to see if it matches the physical MAC address that is stored in RAM. In any case, it will be necessary to modify the MAC address with a new NIC or make modifications via software. However, it is possible for duplicate MAC addresses to exist because of mistakes made during manufacturing, mistakes made in some virtual machine implementation methods, or modifications made using one of several software tools. It is the responsibility of the vendor to ensure that none of its devices be assigned the same MAC address. Therefore, the Ethernet MAC address of that device would be 00-60-2F-3A-07-BC. Cisco would then configure the device with a unique vendor code such as 3A-07-BC. The IEEE has assigned Cisco a OUI of 00-60-2F. Ethernet MAC address hexadecimalįor example, assume that Cisco needs to assign a unique MAC address to a new device. Therefore, an Ethernet MAC address consists of a 6 hexadecimal vendor OUI code followed by a 6 hexadecimal vendor-assigned value, as shown in the figure. Assign a unique value in the last 6 hexadecimal digits. Use its assigned OUI as the first 6 hexadecimal digits.When a vendor assigns a MAC address to a device or Ethernet interface, the vendor must do as follows: To ensure this, all vendors that sell Ethernet devices must register with the IEEE to obtain a unique 6 hexadecimal (i.e., 24-bit or 3-byte) code called the organizationally unique identifier (OUI). Ethernet MAC Address exampleĪll MAC addresses must be unique to the Ethernet device or Ethernet interface. Because a byte equals 8 bits, we can also say that a MAC address is 6 bytes in length. MAC addressing provides a method for device identification at the data link layer of the OSI model.Īn Ethernet MAC address is a 48-bit address expressed using 12 hexadecimal digits, as shown in the figure. The MAC address is used to identify the physical source and destination devices (NICs) on the local network segment. In an Ethernet LAN, every network device is connected to the same, shared media. If such conversions are required, convert the decimal or hexadecimal value to binary, and then to convert the binary value to either decimal or hexadecimal as appropriate. You may have to convert between decimal and hexadecimal values. Hexadecimal may also be represented by a subscript 16, or the hex number followed by an H (e.g., 73H). Hexadecimal numbers are often represented by the value preceded by 0x (e.g., 0x73) to distinguish between decimal and hexadecimal values in documentation. For example, in the table, the binary value 0000 1010 is shown in hexadecimal as 0A. When using hexadecimal, leading zeroes are always displayed to complete the 8-bit representation. Selected Decimal, Binary, and Hexadecimal Equivalents Decimal, Binary, and Hexadecimal Equivalents Given that 8 bits (one byte) is a common binary grouping, binary 00000000 to 11111111 can be represented in hexadecimal as the range 00 to FF, as shown in the next figure. Decimal and Binary Equivalents of 0 to F Hexadecimal Decimal and Binary Equivalents The figure compares the equivalent decimal and hexadecimal values for binary 0000 to 1111. Therefore, a 48-bit Ethernet MAC address can be expressed using only 12 hexadecimal values. Hexadecimal is used to identify an Ethernet address because a single hexadecimal digit represents four binary bits. The hexadecimal numbering system uses the numbers 0 to 9 and the letters A to F.Īn Ethernet MAC address consists of a 48-bit binary value. To understand hexadecimal, you must first be very familiar with binary and decimal. IPv6 addresses and Ethernet addresses are represented using the hexadecimal base sixteen number system. In networking, IPv4 addresses are represented using the decimal base ten number system and the binary base 2 number system.
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