What is an IP Address
The word “IP ” stands for “Internet Protocol.” An Internet Protocol address or IP Address is a unique logical numeric address has assigned to every single computer, printer, switch, router or any other network device. It is the core component of the TCP/IP network. There is no possibility of a network without an IP address. The IP address such as 192.168.1.1 uniquely identifies every host in the network.. There are two parts of the IP address
The network part
The network part specifies the unique number assigned to the network. It also identifies the class of the IP address. All hosts in a network are grouped in a single IP address range which is called it’s net or subnet.
The host part
This is part identify the host uniquely in the network. Each host assigns a unique address from the range of the network. Each network has a different address range and routers that operate on layer 3 connect these different networks.
Note:- Each host on the network, the network part of the address will be the same, but the host part should be different.
How Do IP Addresses Work?
As network devices generate a TCP or UDP segments, it adds a header with source IP address and destination IP address among other information. This PDU (protocol data unit) called a packet. When a router receives a packet, it looks at the destination address in the header and forwards it to the destination network. The packet may pass through multiple routers before it reaches the destination network. Each router it has to go through called a hop.
IP address Fields
This field plays a very important role in sending data through different hops. Version 4 is the most used version in today networking. The Figure below illustrates the header structure of the IPv4 address.
This field shows the version of the IP address. For IPv4 address, this value is 4.
Header length specifies the size of the header itself. The smallest size is 20 bytes. The figure does not show the rarely used options field that is of a variable length. Most IPv4 headers are 20 bytes in length.
The Differentiated Services field marking packets for Different Quality-Of-Service (QoS) levels. For example, data belonging to voice and video protocols have no acceptance for the delay. The DS field marks packets carrying data belonging to these protocols so that they get priority treatment through the network. On the other hand, peer-to-peer traffic considered a major problem and can mark down to give in best effort treatment.
The total length field specifies the size of the packet. The length contains the size of the header including the size of the data.
When a device receives a segment from TCP or UDP, It may require to break the segment into chunks called fragments before sending it out to the network. Identification fields find the fragments that make up the original segment. Each fragment of a segment will have the same identification number.
Used for fragmentation process.
Fragment offset field identifies the fragment number to reassemble the segment in the correct order.
Time to Live (TTL)
The TTL value is set to the originating host. Each router that the packet passes through reduces the TTL by one. If the TTL reaches 0 before reaching the destination; the packet is dropped. This is done to prevent the packet from moving around the network endlessly.
Protocol field identifies the protocol to which the data carrying belongs. For example, a value of 6 implies that the data has a TCP segment while a value of 17 signifies a UDP segment. Apart from TCP and UDP, there are many protocols whose data can carry in an IP packet.
The header checksum field is used to check for errors in the header. Each router and at the destination, a cyclic redundancy check performed on the header and the result should match the value stored in this field. If the value does not match, the packet is discarded.
Source IP address
This field stores the IP address of the source of the packet.
Destination IP address
This field stores the IP address of the destination of the packet.
Network Devices-Repeater, Hub, Switch, Bridge, Router, Gateway - Networkustad
May 27, 2019 @ 7:07 am
[…] require packets formatted in a routable protocol. The global standard being TCP/IP, or simply “IP.” Routers operate at Layer 3 (network layer) of the OSI model and it uses the destination IP […]
Network and Data Link Layer Address - Networkustad
May 27, 2019 @ 6:55 pm
[…] IP address– The IP address of the sending device and the original source of the […]
Network Layer - Introduction, Functions and Protocols - Networkustad
June 6, 2019 @ 12:31 pm
[…] IPv4 also Internet Protocol version 4 […]
Characteristics of IP - Networkustad
June 6, 2019 @ 3:30 pm
[…] IP address with the low overhead protocol is planned. It also provides the functions that required delivering a packet from a source to a destination over an interconnected network. The protocol doesn’t track and manage the flow of packets. The basic characteristics of IP are the following: […]
Limitations of IPv4 Addresses - Networkustad
June 6, 2019 @ 8:42 pm
[…] the usage of Internet would become; so popular and it would have millions of devices using these IP addresses. The IETF defined IPv4 addresses in RFC 791 published in 1981. The first design of IPv4 does not […]
Unicast, Multicast, and Broadcast Addresses » Networkustad
June 8, 2019 @ 4:37 pm
[…] a single destination device. For sending a unicast packet from source to destination, a destination IP address must be in the IP packet header. A destination MAC address must also be present in the Ethernet […]
IP address Classes- Introduction and Explanation » Networkustad
June 18, 2019 @ 5:45 pm
[…] IP address is an identifying number for network devices. It is similar to a home or business address supplying […]
Characteristics of IP - Connectionless, best effort and Media Independent » Networkustad
June 22, 2019 @ 7:57 am
[…] The IP address with the low overhead protocol is planned. It also provides the functions that required delivering a packet from a source to a destination over an interconnected network. The protocol doesn’t track and manage the flow of packets. […]
Positional Number System and Examples » Networkustad
June 23, 2019 @ 6:21 pm
[…] basis for all computers, digital systems, programming languages and also important to understand IP address and IP address […]
Network and Host Portion of IPv4 Address » Networkustad
June 24, 2019 @ 7:14 pm
[…] number is necessary for each network and also each host on the network must require a unique IP address. The IPv4 address is a 32-bit number that uniquely identifies a network number as well as host in […]
Prefix, network, broadcast and host address » Networkustad
June 25, 2019 @ 5:59 pm
[…] is the first logical address of the network that uniquely identifies a network or a subnet. An IP address is the combination of two separate addresses, the network address and host address. But if we […]
Why We Need IPv6? » Networkustad
June 30, 2019 @ 10:54 am
[…] has experienced a huge increase of devices accessing the Internet. Each device required a unique IP address to access the network and internet. The devices have risen from stationary devices to mobile […]
Dynamic Host Configuration Protocol (DHCP) » Networkustad
August 8, 2019 @ 7:43 pm
[…] a client requests an IP address from a Dynamic Host Configuration Protocol server; the Dynamic Host Configuration Protocol server […]
IP Address Planning for Small Network » Networkustad
August 10, 2019 @ 8:34 am
[…] IP address planning is very important for implementing a small network. All hosts within the small network […]
Router File System » Networkustad
August 11, 2019 @ 8:47 am
[…] the copy tftp running-config command in user exec mode and then enter the hostname or IP address where the configuration file is […]
Network Baseline » Networkustad
August 11, 2019 @ 11:55 am
[…] latency issue to address. The figures below illustrates the result of the ping command for the same IP address with different timings and the comparison of […]
Verify Interface Settings » Networkustad
August 20, 2019 @ 11:14 am
[…] illustrates the output of this command. The output displays all interfaces on the router; the IP address assigned interfaces if any. It is also showing the operational status of the interface. The […]
Summary Static Route » Networkustad
August 25, 2019 @ 2:22 pm
[…] The multiple static routes all use the same exit interface or next-hop IP address. […]
Classless Inter-Domain Routing (CIDR) » Networkustad
August 27, 2019 @ 11:43 am
[…] by the subnet mask instead of the value of the first octet of the address. The network portion and host portion of the IP address are also determined by the subnet mask calling the network prefix. The network […]
Data Link and Network Layer Addresses » Networkustad
August 29, 2019 @ 2:57 pm
[…] or may be on the remote network. An IP addresses also know as the network layer addresses. The IP address is also known as a logical address. Any IP packet has contained two network layer […]
Configuring standard ACLs » Networkustad
September 9, 2019 @ 2:22 pm
[…] or denies traffic based on source addresses. It differentiates routes on a network using the IP address. The port and destination of the packet not evaluated. Standard ACLs only contain a list of […]
Introduction to EIGRP - Exclusive » Networkustad
October 30, 2020 @ 11:47 pm
[…] metrics of the other protocol. Enhanced Interior Gateway Routing Protocol can be used not only for Internet Protocol (IP) networks but also for AppleTalk and Novell NetWare […]
What is web hosting? Learn here » Networkustad
January 2, 2021 @ 6:00 pm
[…] of the internet, what really taking place in the background is the procedure that finds your domain IP and ensures the end-user is linked to the ideal […]