The OSI model is a 7 layer model. The OSI model is virtual and used as a guide for networking technology and communication.
Moving forward, we will be focusing primarily on Layer 2 (Ethernet) and how communications at this level work!
The MAC address (Media Access Control) is the hardware address of network devices (especially network cards) used for unique device identification in the network. The MAC address comprises 48 bits / 6 bytes, and is usually written in hexadecimal format. The Least Significant Bit (LSB) of the first byte indicates whether the address is an individual address (&quot;0&quot;), e.g. the address of a network card, or a multicast address (&quot;1&quot;). Manufacturers of network components can purchase address ranges from the IEEE. The first three bytes of the network address serve as the manufacturer's identifier (also termed OUI - O rganization U nique I dentifier). This must comprise global and individual addresses. The remaining three bytes are assigned individually by the manufacturer for each interface. The MAC address in which all 48 bits are set to 1 is used as a broadcast address sent to all the devices in a LAN.
Just like with Layer 2, Layer 3 addresses have a direct correlation to the type of traffic being transmitted! There are however differences between a Layer 2 and Layer 3 Unicast, Multicast and Broadcast addresses.
Each 8 BIT binary representation of the IP address is defined as an Octet!
The Subnet Mask for each range of addresses help define which portion of the 32 bit address is the Network ID and which portion represents the specific device in that Network!
The traditional method of using Class A, B or C contain both the Unicast and Broadcast elements while Class D addresses represent the Multicast Element.
From this calculation, we are also able to identify the Broadcast ID of a particular network segment!