The IPv4 packet header consists of 20 bytes of data.
Chapter 2 introduced the binary, octal, and hexadecimal numbering systems.
Nov 05, · IPv4 Packet Header fields Fabri Oct 28, PM I would like some clarification on Fragment Offset refers to the structure of the IP on the network layer. The IPv4 packet header consists of 14 fields, of which 13 are required. The 14th field is optional and aptly named: options. The fields in the header are packed with the most significant byte first (big endian), and for the diagram and discussion, the most significant bits are considered to come first (MSB 0 bit numbering). The header fields are discussed below: Version (always set to the value 4 in the current version of IP) ; IP Header Length (number of 32 -bit words forming the header, usually five) ; Differentiated Services Code Point (DSCP)(6 bit field, sometimes set to 0, but can indicate a particular treatment, sometimes refelecting the Quality of Service needs of an application to the network.
You need to understand how computers represent information, and how you can move between number systems to represent binary numbers in a more readable form. Internet Addressing To begin our discussion on computer communication over a network, this section looks at the similarities between mail delivery between houses, and data delivery between computers.
The endpoints in mail delivery are houses, and the endpoints between electronic data delivery are computers. Certainly there can be other endpoints in both systems.
Letters can be delivered from a house to a business, from a business to a house, between two businesses, and so on. Electronic data delivery can be from a news service to your cell phone or personal data assistant PDAfrom your computer to your friend's pager, from environmental sensors in a building to the heating and cooling control systems for that building, and so on.
But to keep the discussion simple, it will suffice to concentrate on mail delivery between houses, and electronic data delivery between computers. The first analogy is that an endpoint in a mail delivery system, a house, is equivalent to the endpoint in a computer communication system, a PC.
Figure Equivalent Endpoints in the Mail and Data Communication Systems In the mail delivery system, the function of the post office is to deliver mail to a particular house.
In the computer communication system, the function of the Internet is to deliver data to a particular PC. Yet, in both systems, the endpoint is not the ultimate destination. For mail, the ultimate recipient is a person. For data, the ultimate recipient is an application such as an e-mail program, a web browser, an audio or video program, an instant messaging program, or any number of wonderful applications that exist today.
Figure Final Destinations in the Postal and Electronic Data Delivery Systems Although the ultimate recipient is a person or a software application, the responsibility of the systems stops when the mail, or data, is delivered to the proper house, or computer.
However, as part of the address, you still need the ultimate recipient; either a person or an application, even though this information is not used for delivery to an endpoint. The endpoint uses the name or application to enable delivery to the recipient. Because the two systems are analogous, it is instructive to revisit the format of an address in the mail delivery system and see if you can use a similar format for electronic data delivery: Name Street Number, Street Name City, State Although there are five distinct pieces of information in the mail address name, street number, street name, city, and stateyou can consider an address to contain only four pieces of information.
For endpoint delivery, you can ignore the name field. You are left with Street Number City State The postal system routers core, distribution, and access use the state, city, and street names to deliver the mail from the source access post office to the destination access post office.
The street number is not needed until the mail arrives at the access post office that is directly connected to the destination street.
So, the address can be broken down into State, City, Street Name and Street Number The state, city, and street name information enables the mail to get close to the destination a particular street. The street number is used to deliver the mail to the proper house.
What is the analogy in the computer world to houses on a street?Field Description; Version. The value of this field must be the same for all coalesced segments.
Header Length. The length of a basic IPv4 header without any IP options. The fields in the IP header and their descriptions are Version —A 4-bit field that identifies the IP version being used. The current version is 4, and this version is referred to as IPv4.
IPv4 Packet Structure - Learn IPv4 (Internet protocol Version-4) in simple and easy steps. A beginner's tutorial containing complete knowledge of IPv4 with OSI Model, TCP/IP Model, Packet Structure, Addressing, Classes, . The IPv4 packet header consists of 14 fields, of which 13 are required. The 14th field is optional and aptly named: options.
The fields in the header are packed with the most significant byte first (big endian), and for the diagram and discussion, the most significant bits are considered to come first . Before learning IPv6 datagram header and fields, I recommend you to learn IPv4 datagram header the different fields in IPv4 datagram header also..
IPv6 Datagram Packet Structure. IPv6 has a much simpler packet header compared with IPv4, by including only the information needed for forwarding the IP datagram.
Techopedia explains Internet Protocol Version 4 Packet Header (IPv4 packet header) A byte header contains almost 13 multipurpose fields, which hold specific related object information such as application, data type and source/destination addresses. Description of IPv4 Header Fields Essays: Over , Description of IPv4 Header Fields Essays, Description of IPv4 Header Fields Term Papers, Description of IPv4 Header Fields Research Paper, Book Reports. ESSAYS, term and research papers available for UNLIMITED access. The Next Header field of the last IPv6 header indicates what type of payload is contained in this packet. Standard payload length [ edit ] The payload length field of IPv6 (and IPv4) has a size of 16 bits, capable of specifying a maximum length of ♠ 65 octets for the payload.
IPv4 has a fixed length header . This header contains fourteen fields. IPv6 (Internet Protocol version 6) is the version of IP that followed the IPv4. IPv6 was developed as a solution to the address exhaustion of IPv4. IPv6 packets are also made up of a header and a data section.
What is the difference between IPv4 and IPv6 Headers?