Determine The Estination Mac Address For The Ethernet Frame

#Determine The Estination Address For The Ethernet Frame Code Followed By

Specific addresses point to a specific host on the network.All devices on the circuit receive the frame, verify if there are errors, then compare the destination MAC address from the frame to the MAC address on their LAN interface. Decimal and Binary Equivalents of 0 to F HexadecimalThe destination address can be one of the following: The physical address, such as the MAC address of an Ethernet frame The logical address, such as the IP address of an IP packet Destination addresses can be either specific or general. ARP Broadcast MAC Address - broadcast. The process that a source host uses to determine the destination MAC address is known as Address Resolution Protocol (ARP). The IP address and MAC address combine to deliver data to one specific destination host. A corresponding destination MAC address must also be present in the Ethernet frame header.

The MAC address is used to identify the physical source and destination devices (NICs) on the local network segment. Ethernet MAC AddressIn 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. For example, in the table, the binary value 0000 1010 is shown in hexadecimal as 0A.Hexadecimal numbers are often represented by the value preceded by 0xВ (e.g., 0x73) to distinguish between decimal and hexadecimal values in documentation.Hexadecimal may also be represented by a subscript 16, or the hex number followed by an H (e.g., 73H).You may have to convert between decimal and hexadecimal values. Decimal and Binary Equivalents of 0 to F Hexadecimal Decimal and Binary EquivalentsGiven 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.Selected Decimal, Binary, and Hexadecimal Equivalents Decimal, Binary, and Hexadecimal EquivalentsWhen using hexadecimal, leading zeroes are always displayed to complete the 8-bit representation. Therefore, a 48-bit Ethernet MAC address can be expressed using only 12 hexadecimal values.The figure compares the equivalent decimal and hexadecimal values for binary 0000 to 1111.

Determine The Estination Address For The Ethernet Frame Code Followed By

Assign a unique value in the last 6 hexadecimal digits.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. Use its assigned OUI as the first 6 hexadecimal digits. 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).When a vendor assigns a MAC address to a device or Ethernet interface, the vendor must do as follows: Ethernet MAC Address exampleAll 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.

Frame ProcessingWhen 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. Therefore, the Ethernet MAC address of that device would be 00-60-2F-3A-07-BC.It is the responsibility of the vendor to ensure that none of its devices be assigned the same MAC address. 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.

Unicast MAC AddressIn Ethernet, different MAC addresses are used for Layer 2 unicast, broadcast, and multicast communications.A unicast MAC address is the unique address that is used when a frame is sent from a single transmitting device to a single destination device.Click Play in the animation to view how a unicast frame is processed. This includes workstations, servers, printers, mobile devices, and routers. If there is a match, it passes the frame up the OSI layers, where the de-encapsulation process takes place.Note:В 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.Any device that is the source or destination of an Ethernet frame, will have an Ethernet NIC and therefore, a MAC address.

The features of an Ethernet broadcast are as follows: Broadcast MAC AddressAn Ethernet broadcast frame is received and processed by every device on the Ethernet LAN. The process that a source host uses to determine the destination MAC address associated with an IPv6 address is known as Neighbor Discovery (ND).Note:В The source MAC address must always be a unicast. The IP address and MAC address combine to deliver data to one specific destination host.The process that a source host uses to determine the destination MAC address associated with an IPv4 address is known as Address Resolution Protocol (ARP). A corresponding destination MAC address must also be present in the Ethernet frame header. For a unicast packet to be sent and received, a destination IP address must be in the IP packet header.

Broadcast MAC AddressAs shown in the animation, the source host sends an IPv4 broadcast packet to all devices on its network. In this example the destination MAC address and destination IP address are both broadcasts. This numbering in the address means that all hosts on that local network (broadcast domain) will receive and process the packet.Click Play in the animation to view how a broadcast frame is processed. It is flooded out all Ethernet switch ports except the incoming port.If the encapsulated data is an IPv4 broadcast packet, this means the packet contains a destination IPv4 address that has all ones (1s) in the host portion.

The source will always be a unicast address.As with the unicast and broadcast addresses, the multicast IP address requires a corresponding multicast MAC address to deliver frames on a local network. Because multicast addresses represent a group of addresses (sometimes called a host group), they can only be used as the destination of a packet. The range of IPv6 multicast addresses begins with ff00::/8. The range of IPv4 multicast addresses is 224.0.0.0 to 239.257.257.257. It is not forwarded by a router, unless the router is configured to route multicast packets.If the encapsulated data is an IP multicast packet, the devices that belong to a multicast group are assigned a multicast group IP address. It is flooded out all Ethernet switch ports except the incoming port, unless the switch is configured for multicast snooping.

Applications such as video and imaging software may also use multicast addressing, although multicast applications are not as common. Multicast MAC AddressRouting protocols and other network protocols use multicast addressing. In this example, the destination MAC address and destination IP address are both multicasts.

Determine The Estination Mac Address For The Ethernet Frame