How IPv6 Works

IPv4 vs IPv6 Addresses

IPv4 addresses are written in decimal format with a 32-bit address length. An example of an IPv4 address would look something like x . x . x . x where each “x” is called an octet containing a decimal value between 0 and 255. IPv6 addresses are written in hexadecimal format and divided up into eight 16-bit groups that are separated by a colon. IPv6 addresses use 128 bits which is four times more than IPv4 addresses. An IPv6 address would look something like 2001:0db8:0000:0000:7a6e:0680:9668. Various methods exist to shorten the length of IPv6 addresses. For instance, two colons (::) can take the place of consecutive sections of zeros. In our example, the address may be shortened to 2001:db8::7a6e:680:9668. The structure of the address can be broken up into three parts. The Global Routing Prefix is the portion of the address that is used to identify a specific network or subnet within the larger IPv6 internet. The Subnet ID is the portion of the address that is used to identify subnets within an organization. The host ID is the last part of the address that is used to identify a specific host on a network.

Types of IPv6 Address

" Unicast Addresses: Only one interface is specified by a unicast address. Only one interface is specified by the unicast address. A packet moves from one host to the destination host when it is sent to a unicast address destination.
Multicast Addresses: It represents a group of IP devices and can only be used as the destination of a datagram.
Anycast Addresses: The multicast address and the anycast address are the same. The way the anycast address varies from other addresses is that it can deliver the same IP address to several servers or devices. Keep in mind that the hosts do not receive the IP address. Stated differently, multiple interfaces or a collection of interfaces are assigned an anycast address."
(GeeksforGeeks, 2024)
Unique Local Addresses: This address is like an IPv4 private address. They are meant to be used inside an internal network. They are routable on the internal network but not on the internet.
Link-Local Addresses: These are quick, automatic and private IP addresses that are not routable over a network. They are designed to communicate only within a single area of a network.

Network and Node Addresses

In IPv6, an address is split into two 64-bit segments. The top 64-bit segment is the network component, and the lower 64-bit component is the node component. The network component is used for routing while the node component identifies the address of the interface or node. The node component is derived from the actual physical (MAC) address.

Using IPv6 Addresses in URLs

Just like IPv4 networks, webpages can also be accessed via IPv6. IPv6 addresses must be enclosed in square brackets. Example… HTTP://[2001:db8:4531:674::100e]/webpage.

IPv6 Loopback

A loopback address, also called local host, is the internal address that routes back to the local system. The loopback address for IPv4 is 127.0.01 and in IPv6, the loopback address is 0:0:0:0:0:0:0:1 or ::1. In both IPv4 and IPv6, routers will not forward packets that have an undefined address. ::/0 is the unspecified address for IPv6.