Difference Between IPv4 and IPv6

IPv4 and IPv6 are the versions of internet protocol where IPv6 is the enhanced version of IPv4. There are various differences between IPv4 and IPv6 protocol including their features, but the crucial one is the number of addresses (Address space) it generates.

IP version 4 (IPv4) generates 4.29 x 10⁹ unique network addresses which is insufficient in quantity and as a result Internet is running out of space. Whereas IP version 6 (IPv6) produces 3.4 x 10³⁸ addresses and is a scalable and flexible solution to the current problem.

First of all, let us understand what is Internet protocol. The TCP/IP standard protocol that defines the IP datagram as the unit of information moved across the internet. It is an unreliable and connectionless datagram protocol – a best-effort delivery service. The internet is an abstraction of physical networks and provides the same functionalities like accepting and delivering packets.

IP provides three major things that are:

• Specification of the exact format of all data.
• It performs routing function and chooses path for sending the data.
• It involves a collection of rules that support the idea of unreliable packet delivery.

Content: IPv4 Vs IPv6

1. Comparison Chart
2. Definition
3. Key Differences
4. Conclusion

Comparison Chart

Basis of comparison	IPv4	IPv6
Address Configuration	Supports Manual and DHCP configuration.	Supports Auto-configuration and renumbering
End-to-end connection integrity	Unachievable	Achievable
Address Space	It can generate 4.29 x 109 addresses.	It can produce quite a large number of addresses, i.e., 3.4 x 1038.
Security features	Security is dependent on application	IPSEC is inbuilt in the IPv6 protocol
Address length	32 bits (4 bytes)	128 bits (16 bytes)
Address Representation	In decimal	In hexadecimal
Fragmentation performed by	Sender and forwarding routers	Only by the sender
Packet flow identification	Not available	Available and uses flow label field in the header
Checksum Field	Available	Not available
Message Transmission Scheme	Broadcasting	Multicasting and Anycasting
Encryption and Authentication	Not Provided	Provided

Definition of IPv4

An IPv4 address is a 32- bit binary value, which can be displayed as four decimal digits. The IPv4 address space offers about 4.3 billion addresses. Only 3.7 billion addresses can only be assigned out of 4.3 billion address. The other addresses are conserved for specific purposes such as multicasting, private address space, loopback testing, and research.

IP version 4 (IPv4) uses Broadcasting for transferring packets from one computer to all computers; this probably generates problems sometimes.

Dotted-Decimal Notation of IPv4
128.11.3.31

Packet Format

An IPv4 datagram is a variable-length packet comprised of a header (20 bytes) and data (up to 65,536 along with header). The header contains information essential to routing and delivery.

Base Header

• Version: It defines the version number of IP, i.e., in this case, it is 4 with a binary value of 0100.
• Header length (HLEN): It represents the length of the header in multiple of four bytes.
• Service type: It determines how datagram should be handled and includes individual bits such as level of throughput, reliability, and delay.
• Total length: It signifies the entire length of the IP datagram.
• Identification: This field is used in fragmentation. A datagram is divided when it passes through different networks to match the network frame size. At that time each fragment is determined with a sequence number in this field.
• Flags: The bits in the flags field handles fragmentation and identifies the first, middle or last fragment, etc.
• Fragmentation offset: It’s a pointer that represents the offset of the data in the original datagram.
• Time to live: It defines the number of hops a datagram can travel before it is rejected. In simple words, it specifies the duration for which a datagram remains on the internet.
• Protocol: The protocol field specifies which upper layer protocol data are encapsulated in the datagram (TCP, UDP, ICMP, etc.).
• Header checksum: This is a 16-bit field confirm the integrity of the header values, not the rest of the packet.
• Source address: It’s a four-byte internet address which identifies the source of the datagram.
• Destination address: This is a 4-byte field which identifies the final destination.
• Options: This provides more functionality to the IP datagram. Furthermore can carry fields like control routing, timing, management, and alignment. IPv4 is a two-level address structure (net id and host id) classified into five categories (A, B, C, D, and E).

Definition of IPv6

An IPv6 address is a 128-bit binary value, which can be displayed as 32 hexadecimal digits. Colons isolate entries in a sequence of 16-bit Hexadecimal fields. It provides 3.4 x 10³⁸ IP addresses. This version of IP addressing is designed to fulfill the needs of exhausting IP’s and providing sufficient addresses for future Internet growth requirements.

As IPv4 uses two-level address structure where the use of address space is insufficient. That was the reason for proposing the IPv6, to overcome the deficiencies IPv4. The format and the length of the IP addresses were changed along with the packet format and protocols were also modified.

Hexadecimal Colon Notation of IPv6
FDEC:BA98:7654:3210:ADBF:BBFF:2922:FFFF

IPv6 Packet format

Each packet is consist of a mandatory base header succeeded by the payload. The payload includes two parts namely optional extension headers and data from an upper layer. The base header consumes 40 bytes, inversely the extension headers and data from the top layer usually hold up to 65,535 bytes of information.

Base Header

• Version: This four-bit field specifies the version of the IP, i.e., 6 in this case.
• Priority: It defines the priority of the packet concerning traffic congestion.
• Flow label: The reason for designing this protocol is to facilitate with special controlling for a certain flow of data.
• Payload length: It defines the total length of the IP datagram excepting the base header.
• Next header: It’s an eight-bit field describe the header that trails the base header in the datagram. The next header is one of the optional extension headers which IP uses or the header for an upper-layer protocol such as UDP or TCP.
• Hop limit: This eight-bit hop limit field assist with the same functions at the TTL field in IPv4.
• Source address: It is a 16 bytes internet address identifies the source of the datagram.
• Destination address: This is 16-byte internet address that generally describes the final destination of the datagram.

Conclusion

IPv6 retains many of the core concepts from the current protocol, IPv4 but changes most details. IPv4 was devised as a transport and communications means, but the number of addresses came to exhaustion that was the reason for the development of IPv6. IPv6 provides scalability, flexibility and seamless possibilities in the field of networking.