What is IPv6?

IPv6 is the most recent version of the Internet Protocol (IP) Addressing System. IPv6 is an addressing system, comparable to street addresses, for routing to devices over the Internet. The addresses under IPv4 have been exhausted, leading to workarounds. IPv6 is designed to extend the address space of internet-connected devices and provide new features such as IPsec support, eventually deprecating IPv4.

Internet Protocol is a method that computers use to send information across the Internet. Based on specific procedures, a computer converts information into smaller data packets, assigns an IP address to them, and sends them to the destination IP address. An IP address is a unique identifier assigned to every device connected to a network. IPv4 is the original IP address scheme that devices use to exchange information. However, IPv4 is running out of address space due to the introduction of numerous connected devices. Therefore, the Internet Engineering Task Force (IETF) introduced IPv6 to overcome the limit. Many internet service providers now support IPv6, allowing internet-connected devices to exchange data with the next-generation Internet Protocol.

Both IPv4 and IPv6 are distinct protocols bearing varying architectures. Here are some key differences:

• Address space. IPv4 supports up to 2³² or approximately 4.2 billion addresses. Meanwhile, IPv6 supports up to 2¹²⁸ or approximately 340 undecillion addresses.
• Address representation. IPv4 uses numerical IP addresses, such as 192.168.1.104. Meanwhile, IPv6 represents internet addresses with hexadecimal values, such as 2600:1400:d:5a3::3bd4
• Communication. IPv4 supports multicast and broadcast transmission, which allows devices to send data packets to multiple destinations in different ways. Conversely, IPv6 doesn’t support broadcast transmission. Instead, it uses multicast and anycast to achieve similar results.

IPv6 allows significantly more devices to communicate on the Internet using their own IP addresses. It overcomes limitations in IPv4 by increasing the address space, simplifying data packet processing, enhancing data security, and facilitating automated network configuration. To implement IPv6, the internet service provider, routers, personal computers, and other internet-enabled devices must support the protocol. Below are key concepts on which IPv6 is built.

Addressing

IPv6 uses 128-bit addressing to give computers, mobile phones, the Internet of Things (IoT), and other devices a unique address. An IPv6 address consists of eight groups of four hexadecimal digits that are separated by colons (:).

For example, below is an IPv6 address.

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

In actual applications, you compress IPv6 addresses by omitting groups of zero and replacing them with a double colon (::). The double colon notation can only appear once in the shortened form of the IPv6 address.

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

The IPv6 address can be divided into two 64-bit segments.

• The upper 64 bits are the network prefix that contains routing information.
• The lower 64 bits are an interface identifier that stores unique information about a network device.

We can categorize IPv6 addresses into unicast, anycast, and multicast.

• A unicast address directs the data packet to a single device.
• An anycast address allows the sender to forward the data packet to the nearest device that belongs to a group of devices sharing the same address.
• A multicast address forwards information to all destination addresses that belong to a group.

Depending on the type of address, an IPv6 router will handle the data packets differently.

Neighbor discovery

Neighbor discovery is a process that identifies the MAC addresses of devices connected to the same network. IPv6 devices use the Neighbor Discovery Protocol (NDP) to discover routers, assign themselves an IP address, and locate other computers they can communicate with. When connected to a network, devices use different types of Internet Control Messaging Protocol (ICMP) messages to collect information and configure network settings. They include:

• Router Solicitation (RS), which allows a device to request information from routers.
• Router Advertisement (RA), which is a router’s response to an RS message or a periodical update of its own information on the network.
• Neighbor Solicitation (NS) allows a device to request information from other devices.
• Neighbor Advertisement (NA), which is a response to the NS message, consists of the device’s MAC address and other network information.
• Redirect, which provides a device with a better route to send information.

Routing

Routing is a process where a router determines the network path to send a data packet. IPv6 routing shares similarities with routing in IPv4 networks. An IPv6 router refers to the routing table, destination IP address, and nearby routers to chart the best path. You can configure a router to support static and dynamic routing. Static routing forwards the data packet based on prefixed rules. Meanwhile, dynamic routing uses special protocols like Open Shortest Path First for IPv6 (OSPF) to optimize the routes.

Dual stack implementation

Organizations are adopting IPv6 while supporting IPv4 addresses. Because IPv6 is not backward compatible with IPv4, they implement dual-stacking to support both protocols. It allows routers, devices, and workloads to communicate with either IPv6 or IPv4.

IPv6 enables preparedness for an increasingly crowded public internet space with these features.

Address space

IPv6 provides more address space for connected devices with a 128-bit addressing format. By adopting IPv6, organizations can scale their corporate networks without worrying about limited IP addresses. The larger address space also simplifies peer-to-peer communication devices because no additional address resolution mechanisms are required.

Simplified header

IPv6 uses a simple packet header that enables efficient routing and processing. A packet header is a block of information that provides the necessary instructions to routers and devices. IPv6 removes or shifts some of the fields originally found in the IPv4 header.

Advanced routing

Routings in IPv6 are fast and efficient because of the simplification of the data packet’s header. Additionally, IPv6 supports advanced routing methods like route aggregation and hierarchical routing. These methods enable the router to maintain a smaller, more organized route table that contains precise routing information.

Security with IPsec

IPSec is available in IPv6 through an extension header to provide robust security. When you transmit data in IP networks, you can secure information by turning on the encryption and authentication features. This feature is not enabled by default; you must configure it.

Extension headers

Extension headers are additional information appended to the IPv6 data packets. Similar to IPv4 headers, they contain special information intended for the destination device to reassemble the sequences of data. However, in IPv6, these headers are not processed by routers, which improves routing efficiency.

No network address translation (NAT)

Network address translation (NAT) is a technology that allows multiple devices within a local network to access the Internet using a single public IP address. With IPv6, NAT is no longer needed because of the vast amount of address space available. Every device within a local network uses a unique IP address when browsing websites, sharing files, or performing other activities on the Internet. Devices that support IPv6 can configure their address automatically by using a special feature called Stateless Address Autoconfiguration (SLAAC).

Quality of service

IPv6 allows routers to prioritize data packets differently, such as enabling consistent speed, through a special field called flow support. This way, devices can handle bandwidth-intensive packet flow more effortlessly.

Many AWS services offer dual-stack and IPv6 connectivity, allowing you to conduct your cloud-based network management with the latest internet protocol version.

• The Amazon CloudFront content delivery network offers native IPv6 support for incoming connections, serving content to customers over IPv6.
• Application Load Balancers support native Internet Protocol version 6 (IPv6) in a VPC. This allows clients to connect to the Application Load Balancer with IPv4 or IPv6.
• Amazon Route 53 allows you to route end users to your site reliably over IPv6 with globally-dispersed Domain Name System (DNS) servers and automatic scaling.
• Amazon Virtual Private Cloud (Amazon VPC) gives you full control over your virtual networking environment, including resource placement, connectivity, and security. Amazon VPC offers native IPv6 support.

Get started with building IPv6 network applications on AWS by creating a free account today.