used to identify a host within a local network. Hardware addressing is the function of the data-link layer of the OSI model (layer 2)
A MAC address is most often represented in hexadecimal, using one of two accepted formats:
00:43:AB:F2:32:13
0043.ABF2.3213
The first six hexadecimal digits of a MAC address identify the manufacturer of the physical network interface. This is referred to as the OUI (Organizational Unique Identifier). The last six digits uniquely identify the host itself, and are referred to as the host ID.
The MAC address has one shortcoming – it contains no hierarchy. MAC addresses provide no mechanism to create boundaries between networks. There is no method to distinguish one network from another.
Logical addressing
Logical addressing is a function of the Network layer of the OSI Model (Layer-3), and provides a hierarchical structure to separate networks. Logical addresses are never hardcoded on physical network interfaces, and can be dynamically assigned and changed freely.
A logical address contains two components:
Network ID – identifies which network a host belongs to.
Host ID – uniquely identifies the host on that network
Internet Protocol (IP)
IP provides two fundamental Network layer services:
Logical addressing – provides a unique address that identifies both the host, and the network that host exists on.
Routing – determines the best path to a particular destination network, and then routes data accordingly.
IP is the primary protocol in the Internet Layer of the Internet Protocol Suite and has the task of delivering distinguished protocol datagrams (packets) from the source host to the destination host solely based on their addresses. For this purpose the Internet Protocol defines addressing methods and structures for datagram encapsulation.
IPv4 employs a 32-bit address, which limits the number of possible addresses to 4,294,967,296. IPv4 will eventually be replaced by IP Version 6 (IPv6), due to a shortage of available IPv4 addresses.
IPv4 Addressing
A core function of IP is to provide logical addressing for hosts. An IP address provides a hierarchical structure to both uniquely identify a host, and what network that host exists on.
An IP address is most often represented in decimal, in the following format:
158.80.164.3
An IP address is comprised of four octets, separated by periods:
First Octet Second Octet Third Octet Fourth Octet
158 80 164 3