IP Headers: IPv4 vs IPv6

Analyze IPv4 and IPv6 Packet Headers to understand the difference and usage of different fields

155 Participants 30 Minutes Beginner

Welcome to our IP Headers and IPv4/IPv6 Packet Analysis lab, where we delve into the fundamentals of Internet Protocol (IP) networking. In this hands-on session, we will cover IP headers, explore the differences between IPv4 and IPv6, and dissect packets using Wireshark for insightful analysis. Through practical demonstrations and interactive exercises, participants will gain a comprehensive understanding of IP addressing, header structures, packet routing, and the transition from IPv4 to IPv6.



What are IP Headers 

IP headers, short for Internet Protocol headers, are crucial components of IP packets used in computer networking. They contain essential information required for the proper routing and delivery of data packets across networks. IP headers are added to the beginning of each packet and typically consist of several fields, each serving a specific purpose. Some of the key fields found in IP headers include:

  • Version: Indicates the version of the Internet Protocol being used (e.g., IPv4 or IPv6).

  • Header Length: Specifies the length of the IP header in 32-bit words.

  • Type of Service (TOS): Originally used for specifying quality of service (QoS) parameters, now often replaced by Differentiated Services Code Point (DSCP) and Explicit Congestion Notification (ECN).

  • Total Length: Specifies the total length of the IP packet, including the header and payload.

  • Identification: A unique identifier assigned to each IP packet, used for fragmentation and reassembly purposes.

  • Flags: Flags used for fragmentation control, including the "Don't Fragment" (DF) and "More Fragments" (MF) flags.

  • Fragment Offset: Indicates the position of a fragment within the original unfragmented packet.

  • Time to Live (TTL): Specifies the maximum number of hops (routers) that the packet can traverse before being discarded.

  • Protocol: Specifies the higher-layer protocol (e.g., TCP, UDP, ICMP) used in the data payload of the packet.

  • Header Checksum: A checksum calculated over the entire IP header, used for error detection during packet transmission.

  • Source IP Address: The IP address of the sender (source) of the packet.

  • Destination IP Address: The IP address of the intended recipient (destination) of the packet.

IP headers play a critical role in the routing and delivery of packets across IP networks, enabling devices to forward data packets to their intended destinations efficiently and reliably.


What is ipv4 and ipv6 

IPv4 (Internet Protocol version 4) and IPv6 (Internet Protocol version 6) are two versions of the Internet Protocol, the primary protocol used for communication over the Internet. Here's an explanation of each version in points:



  • IPv4 is the fourth version of the Internet Protocol and has been the dominant protocol used on the Internet for several decades.

  • It uses a 32-bit address scheme, allowing for approximately 4.3 billion unique addresses.

  • IPv4 addresses are written in decimal notation, separated by periods (e.g.,

  • The address space is almost exhausted due to the rapid growth of the Internet and the increasing number of connected devices.

  • IPv4 addresses are divided into five classes: A, B, C, D, and E, each with its own range of addresses for different purposes.

  • It uses techniques like Network Address Translation (NAT) to conserve address space and allow multiple devices to share a single public IP address.

  • IPv4 addresses are susceptible to address exhaustion and have limitations in terms of scalability, security, and support for new features.

  • Despite the limitations, IPv4 remains widely used across the Internet and most networking devices are compatible with it.



  • IPv6 is the sixth and latest version of the Internet Protocol, designed to address the limitations of IPv4 and accommodate the growing number of Internet-connected devices.

  • It uses a 128-bit address scheme, providing an enormous address space capable of accommodating approximately 340 undecillion (3.4×10^38) unique addresses.

  • IPv6 addresses are written in hexadecimal notation, separated by colons (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334).

  • The larger address space of IPv6 allows for improved scalability, enhanced security features, and support for new technologies and services.

  • IPv6 incorporates features like stateless address autoconfiguration, multicast addressing, and built-in support for IPsec (Internet Protocol Security).

  • It eliminates the need for NAT by providing a large enough address space to assign unique addresses to every device connected to the Internet.

  • IPv6 deployment has been ongoing, with many Internet service providers, networking equipment manufacturers, and websites adopting IPv6 to future-proof their networks and services.

  • While IPv6 adoption continues to grow, IPv4 and IPv6 will coexist for the foreseeable future, with transition mechanisms allowing for interoperability between the two protocols.


In conclusion, understanding IP headers and the differences between IPv4 and IPv6 is essential for anyone involved in networking or cybersecurity. IP headers provide critical information for routing and delivering data packets across networks, while IPv4 and IPv6 represent different generations of the Internet Protocol, each with its own unique characteristics and capabilities. As the Internet continues to evolve and accommodate an ever-expanding array of devices and services, a solid grasp of IP fundamentals will remain indispensable for navigating the complexities of modern networking landscapes.

IP Headers: IPv4 vs IPv6


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