parate workstation interface at each segment. 6.5.4 Frame Structure of the Ethernet The MAC frame structure of IEEE 802.3/ISO 8802-3 is shown in Figure 6.27. Another popular frame structure that can be used is Ethernet II, which is also known as Ethernet V2.0 or DIX Ethernet or Ethertype or Link segments Repeater Cable segment Figure 6.26 Example of a coaxial Ethernet network. Introduction to Telecommunications Network Engineering Start-of-frame Length-of- delimiter data field Data: Destination Source (or type) LLC PDU frame check Preamble address address (or user data) sequence 7 bytes 0...1500 0...46 Calculation of FCS 64-1518 bytes Address fields (6 bytes): I/G = Individual/group address = 0; Address of individual workstation 46 bits = 1; Address of a group of workstations U/L = Universal/local address Manufacturer Serial number = 0; Global address 22 bits 24 bits = 1; Local address Figure 6.27 Frame structure of the Ethernet (MAC). ARPA. They can coexist in the same LAN but communicating computers have to use the same frame structure. Now we explain the purpose and structure of the fields in the both popular frame types. Each frame starts with the preamble of 7 bytes, each containing the bit pattern 10101010. The Manchester encoding produces a 10-MHz square wave that helps the receivers to synchronize with the sender. The start-of-frame delimiter contains the bit sequence of 10101011 and indicates the start of the frame. Both addresses contain 6 bytes, with the first bit indicating if it is the address of an individual workstation or a group address. Group addresses may be used for multicast where all stations belonging to the same group receive the frame. The second bit indicates whether the address if defined locally or if it is a unique global address. Normally global addresses are used and they are unique for each network card in any computer. The IEEE allo- cates an address range for each LAN card manufacturer [3]. When a card is manufactured, the manufacturer and serial number are programmed into it (se