0 TCP IP STEP 1

IP ADDRESSING EXPLAINED

So far, we have learned how TCP and IP work together to move data across a network. In this section, we cover what IP addresses are and what is needed in conjunction with an IP address to move data. This section helps you understand why IP addresses are so necessary and how they are used on TCP/IP networks.

Ethernet Addresses
Each Ethernet interface or Ethernet network card installed on a network has its own unique hardware address, known as an Ethernet address or media access control (MAC) address.

A MAC address is a 48-bit number that is preprogrammed by the manufacturer of the hardware device. MAC addresses consist of a unique six-part number annotated in hexadecimal; the value of each part ranges from 00 to FF. The first three parts of the MAC address are called the organizationally unique identifier (OUI) and are assigned by the Institute for Electrical and Electronics Engineers (IEEE). OUIs are purchased by Ethernet device manufacturers, who then assign the last three parts of the MAC address, thereby making each address assignment unique. For example, 01:b7:a3:0b:e1:19 is a MAC address, where 01:b7:a3 is the OUI and 0b:e1:19 is the unique number assigned by the manufacturer.