IP Addressing and Subnetting
The most important feature of Internet Protocol (IP) is to assign addresses to packets and is responsible for carrying the data and route them to the correct destination. Hence it is essential to understand an IP Address and its components. For each computer to communicate a unique IP address is required. IP Address has two parts – Network Address and Host Address. In this lesson, the details of IP addressing are discussed in detail.
A clear understanding of this concept along with its related concepts like subnetting, installing, and configuring TCP/IP address on a workstation and other IP addressing concepts would enable you to work independently on Jous related to these concepts. Also, some amount of practical working experience on the same would help you troubleshoot IP address-related concepts with ease.
Media Access Control or MAC address is a hardware address that uniquely identifies each node of a network. MAC addresses are physical addresses, which are 12-digit hexadecimal numbers. It is also known as hardware addresses or physical addresses. MAC address forms the basis of network communication, regardless of the protocol used to accomplish network connection. By convention, MAC addresses are usually written in one of the following two formats:
The first half of a MAC address contains the ID number of the adapter manufacturer. The second half of a MAC address represents the serial number assigned to the adapter by the manufacturer.
Why MAC address?
MAC address generally functions at the data link layer and they allow computers to uniquely identify themselves on the network at this relatively low level.
The IP address of the machine exists on the third layer of the OSI model and when a packet reaches the computers it will travel upwards from layer 1 (Physical layer) to layer 2 (Datalink layer). The physical layer recognizes ti signals on the network and creates the frame which is passed to the Datalink Javer. If the packet is destined for the computer, then the MAC address in the destination field of the packet will match, so it accepts and passes it to the Network layer (layer 3) which in turn, checks the IP address of the packet to make sure it matches with the IP address to which the computer has been configured.
What are the IP address and its parts?
Internet Protocol (IP) address is a unique number used to identify a computer and communicate with each other on a network. The IP address is a 32-bit value that is divided into four 8 bit fields called an octet. An IP Address consists of two parts, a network address, and a host address. The numbers in the IP addresses range from 18.104.22.168 to 255.255.255.255. This is known as dotted decimal notation.
The two parts of the IP address are:
1. Network Address
2. Host Address
1. Network Address: Network Address is the first part of the IP address which is used to uniquely identify the network in a large TCP/ IP network environment. Each network must know its own address on the Internet and that of the other networks with which it communicates. The organization requires a unique network number, which it can request from Network Information Center (NIC). This unique network number is added to the packet, which is sent from the network onto the Internet.
2. Host Address: The Host address is used to uniquely identify the host in the particular network identified by the Network portion of the IP Address. In addition to a network address or number, information is required to identify which specific host or machine in a network is sending or receiving a message. Therefore, IP address needs a unique network number and a host number.
Why is IP Addressing?
Every host on a TCP/IP network needs to have a unique address to send the data from one host to another. Every data packet contains addressing information in the header, and the IP address in the header is used to route packets. IP addresses are unique on each network to identify the appropriate host. IP addressing is basically configuring each TCP/IP host with a valid IP address. In order to access the Internet, a host must have an IP address that identifies not only the host address but also identifies the network address. An administrator needs to be aware of proper addressing techniques so that the hosts on the network will function correctly.
IP addresses are mainly used to deliver the data packets across the network for which the source and destination IP address remains constant as the data packet traverses. Each time a packet travels through a router; the router will refer to its routing table to see if it can match the network number of the destination IP address with an entry in its routing table. If a match is found, the packet is forwarded to the next-hop router for the destination network in question. If a match is not found, the packet may be forwarded to the router defined as the default gateway, or the router may drop the packet.
IP Address Classes
An IP Address is given to a system to identify the system uniquely on the Network. The IP Address is made of 32 Bits and has two portions namely the Network portion and the Host Portion. The 32 Bits are divided into four octets each octet having 8 bits. The binary digits are converted into decimal and they are represented in dotted-decimal format. The value of each octet can vary from 0 to 255.
IP address is mainly categorized into five classes.
|Class||Value of the first byte||Value of first bits||No. of Networks / No. of bits for N/W||No. of hosts / No. of bits for hosts||Purpose|
|A||1 – 126||0||126/8||16,777,214/24||Large network with many devices|
|B||128 – 191||10||16,384/16||65,534/16||Medium-sized to Large Sized network|
|C||192 – 223||110||2,097,152/24||254/8||Small networks used for LAN|
|D||224 – 239||1110||——-||——-||Used for Multicasting|
|E||240 – 254||1111||——-||——-||Reserved for future use|
Identify the components and structure of IP address (IPv4, IPv6)
There are two versions of IP which are in use today. Most of all the networks use IP version 4 (IPv4) but a number of educational and research networks have adopted the next generation IP version 6 (IPv6)
IPv4 Addressing Notation
IPV4 addresses are 32-bits (4-byte) also called octets. Each byte is 8 bits in length and each octet in an IP address ranges from a minimum of 0 to a maximum of 255. Therefore the full range of IP addresses is from 0.0.0.0 through 255.255.255.255, which limits the address space to 4.294.967.296 possible unique addresses. On the other hand, many are reserved for special purposes such as private networks or multicast addresses. IPV4 usually appears in the equivalent dotted-decimal representation.
IPV6 Addressing Notation
IPV6 addresses are 128 bits (16 bytes) long. It is intended to provide more addresses for networked devices allowing each cell phone and mobile electronic device to have its own address. IPV6 addresses are generally written in the following form:
This notation represents a pair of IPV6 bytes are separated by a colon and each byte is represented as an equivalent
IP addressing methods
Computers use IP addresses to locate and talk to each other on the internet, much the same way people use phone numbers to locate and talk to one another on the telephone.
Static IP Address
A static IP Address is a number that is assigned to a computer by an administrator to be its permanent address on the Internet. To configure the IP settings,
- Right click on My Network Places
- Select Properties
- Double Click on Local Area Connection,
- Click on Properties.
- Double click on Internet Protocol (TCP/IP)
Dynamic IP Address
A Dynamic IP Address is one that is temporarily assigned to the devices by a DHCP server that maintains and assigns IP Address. in order to assign the dynamic IP address click on Obtain an IP address automatically option as shown.
Automatic Private IP addressing
Automatic Private IP Addressing is a Windows-based computer. It is configured to use DHCP which can automatically assign itself an Internet Protocol (IP) address if a DHCP server is not available. This is possible on a network without a DHCP server or on a network if a DHCP server is temporarily down for maintenance. It enables a computer to assign itself an Internet Protocol (IP) address in the event that a DHCP server is not available or does not exist on the network.
When the network adapter has been assigned an IP address, the computer can use TCP/IP to communicate with any other computer that is connected to the same LAN and that is also configured for APIPA or has the IP address manually set to the 169.254.x.y (x.y is the client’s unique identifier) address range with a subnet mask of 255.255.0.0. If the computer cannot communicate with each other on other subnets or with computers that do not use auto- Matic private IP addressing, Automatic Private IP Addressing is enabled by default.