IPv4 and IPv6 overview

IP stands for internet protocol. The internet protocol is the protocol which allows internetworking at the internet layer of the internet protocol suite. IPv4 is the fourth version of the protocol and IPv6, as the name implies, is the sixth version.

IPv4

IPv4 is the fourth version of IP. It was bought into action by deploying on SATNET in 1982 and on the ARPANET in January 1983. As compared to IPv6, IPv4 still is widely used and contributes almost 95% of internet traffic to date. 

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IPv4 provides addressing capability of approximately 4.3 billion addresses. It works as a network layer of ISO-OSI models. Being a connectionless protocol, it makes the best effort to deliver the packet to the destination.

IPv4 address range

IPv4 has an address of 32 bits. The address is divided into four parts, each part separated by a dot. Each part is known as an octet, so there are four octets in an IPv4 address. For example: 100.101.102.103. The range of each octet is 0-255.

IPv4 address classes

IPv4 addresses have been divided into various classes depending on the range of IP addresses. They are as follows:

1. Class A - 1.XXX.XXX.XXX - 127.XXX.XXX.XXX
2. Class B - 128 XXX.XXX.XXX - 191. XXX.XXX.XXX
3. Class C - 192.XXX.XXX.XXX - 223.XXX.XXX.XXX
4. Class D - 224.XXX.XXX.XXX - 239.XXX.XXX.XXX
5. Class E - 240.XXX.XXX.XXX - 255.XXX.XXX.XXX

Private IP ranges

The following IP ranges in IPv4 are private IP addresses and are used internally within the network:

• 10.0.0.0 – 10.255.255.255
• 172.16.0.0 – 172.31.255.25
• 192.168.0.0 – 192.168.255.255

IPv6

IPv6 was introduced in December 1995. It was developed by the Internet Engineering Task Force (IETF) and is the most recent version of the internet protocol. IPv6 is more advanced than IPv4 and also provides better features. 

Each device on the internet is assigned a particular unique IP address for identification of device and location definition. IPv6 was developed to solve the long-anticipated problem of address exhaustion in IPv4. After commercialization, the internet grew rapidly in the 1990s, and it became evident that far more addresses would be needed to connect the devices on the internet than the IPv4 address space had available. IPv6 has the potential to provide an infinite number of addresses to the devices and is replacing IPv4 to cater to the growing number of networks globally and to solve the IP address exhaustion problem. 

Address format

Unlike IPv4, a typical IPv6 address consists of 128 bits. It consists of eight groups, each group representing 16 bits as shown below. Each group contains four hexadecimal digits separated by “:”. For example: 

2001:0db8:85a3:0000:0000:8a2e:0370:7334

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IPv6 reserved addresses

The following are the IP addresses used for special purposes in IPv6.

• ::/128 – Unspecified address
• ::/0 – Default route
• ::1/128 – Loopback address
• FF02::5 – OSPFV3
• FF02::6 – OSPFV3 routers
• FF02::9 – RIPng
• FF02::A – EIGRP

Differences between IPv4 and IPv6

1. The major difference in the IPv4 and IPv6 addressing is the appearance of the IP addresses. IPv4 uses four one-byte decimal numbers separated by a dot (e.g., 192.168.0.1). On the other hand, IPv6 uses hexadecimal numbers separated by colons (e.g., fe80::d4a8:4521:d2d8:d8f4b11).
2. IPv4 and IPv6 are numeric and alphanumeric addressing methods respectively.
3. The length of IPv4 address is 32-bit while length of IPv6 is 128-bit.
4. IPv4 and IPv6 offer 12- and eight-headers fields respectively.
5. Broadcasting feature is supported only by IPv4, not IPv6.
6. The checksum field is absent in IPv6 and present in IPv4.
7. The concept of virtual length subnet masking is applicable only to IPv4.
8. For mapping MAC addresses, IPv4 uses ARP while IPv6 makes use of NDP.
9. IPv4 supports manual and DHCP address configurations, and IPv6 supports auto and renumbering address configuration
10. IPv4 can generate address space up to 4.29 billion whereas IPv6 can generate up to 3.4 x 10^38 of address space. 

The advantages of IPv6 over IPv4

1. IPv6 provides more efficient routing, since it considerably reduces routing table size.
2. Packet processing is more efficient, since packet headers are more simplified.
3. Simplified routers’ tasks, compared to IPv4.
4. IPv6 allows for bigger payloads than IPv4.
5. IPv6 has a simpler header format, as compared to IPv4.
6. In IPv6, authentication and private support is built in, as compared to IPv4.

Sources

1. Differences between IPv4 and IPv6, Linksys
2. IPv6 - Special Addresses, Tutorialspoint
3. IPv4 vs. IPv6, ThousandEyes
4. IPv4 vs IPv6: Understanding the Differences and Looking Ahead, PhoenixNAP