What Is IPv6 (Internet Protocol Version 6)? Definition, Features, and Uses
The IETF’s newest internet protocol, IPv6, helps locate computers on a network and route traffic while driving scalability.
IPv6 is the newest version of internet protocol formulated by the IETF, which helps identify and local endpoint systems on a computer network and route online traffic while addressing the problem of IPv4 address depletion due to prolonged internet use worldwide. This article explains how IPv6 works, its key features, and the challenges to expect during IPv6 implementation.
Table of Contents
What Is IPv6 (Internet Protocol Version 6)?
IPv6 is the newest version of internet protocol formulated by the Internet Engineering Task Force (IETF), which helps identify and local endpoint systems on a computer network and route online traffic while addressing the problem of IPv4 address depletion due to prolonged internet use worldwide.
Internet protocol version 6 (IPv6) is a network layer protocol that allows communication to take place over the network. Each device on the internet has a unique IP address used to identify it and figure out where it is. At the time of the digital revolution of the 1990s, it became apparent that the IP addresses that Internet Protocol version 4 (IPv4) used to connect devices would not be enough to meet demand.
Therefore, the IETF set on developing the next-generation internet protocol. IPv6 became a draft standard for the IETF in December 1998, and on July 14, 2017, it was approved as an internet standard for global rollout.
Limitations of IPv4 and the need for IPv6
IPv4 addresses were getting depleted due to the rapid growth of internet users, high usage of devices such as mobiles, laptops, and computers, inefficient address use, and always-on devices like cable modems. To mitigate the problem of address depletion in IPv4, technologies such as classful networks, classless inter-domain routing, and network address translation were developed. These technologies contributed to the solution by implementing improvements in the backbone of the web’s address allocation and routing systems.
The IPv6 packet is built with 40 extended octets so that users can scale the protocol for the future without disrupting its core structure. The packet has two parts: the header and the payload. IPv6 introduced jumbograms that enabled the packet to handle over 2^32. Jumbograms enhance performance over high maximum transmission unit (MTU) links and tackle the payload.
Further, IPv6 has a 128-bit address and has a larger address space available for future allocation. The 128-bit address is broken into 8 groups, each containing 16 bits. Four hexadecimal numbers represent each group, and colons are used to divide each group from the others. IPv6 provides a host connected to the network with a unique identifier specific to the subnet.
The addressing structure of IPv6, which is established in RFC 4291, makes it possible for three distinct kinds of communications to take place — i.e., the unicast, anycast, and multicast communication methods.
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Advantages of using IPv6
The technology provides internet users with several advantages:
- IPv6 provides a solution to address the global issue of depleting address spaces due to increased demand for IP addresses due to technological advancements.
- It offers reliability and faster speeds. IPv6 supports multicast addresses, meaning bandwidth-intensive packet flows like media streams can reach many destinations simultaneously.
- It enforces more robust network security than IPv4. IPv6 has IPSecurity, which ensures data privacy and data integrity. It also reinforces routing efficiency.
- It supports stateless and stateful address configuration regardless of the presence or absence of a Dynamic Host Configuration Protocol (DHCP) server.
- It has a larger address space and can handle packets more efficiently.
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Disadvantages of using IPv6
However, it also comes with a few constraints. For example, IPv6 is not backward compatible with IPv4. Communication between a device and a network with different internet protocols is difficult.
Despite IPv4 being of inferior quality, offering lower performances, and having its address spaces nearly depleted, it is still more popular than IPv6. Full migration to IPv6 will take an exceptionally long time due to the incompatibilities between the two protocols and the significant expenses associated with transitioning to IPv6 infrastructure.
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How Does IPv6 Work?
The working of IPv6 relies on the following key concepts:
1. IPv6 addresses
An IPv6 address uses 128 bits, four times more than the IPv4 address, which uses only 32 bits. IPv6 addresses are written using hexadecimal rather than dotted decimal, as in IPv4. An IPv6 address consists of 32 hexadecimal numbers since a hexadecimal number uses 4 bits. These numbers are grouped into eight groups of 4’s and are written with a colon (:) as a separator. For instance, group6:, group7:, group8:, etc.
An IPv6 address may be shortened using various techniques due to its length. For instance, 2001:0db8:0000:0000: 0000:7a6e: 0680:9668 may be shortened to 2001:db8::7a6e: 680:9668. The main technique employed is the removal of leading zeros. Additionally, consecutive sections of zeros can be replaced with two colons (::), even though you may only use this approach once in a given address to avoid making the address indeterminate or ambiguous.
2. Network and node addresses
In IPv4, address classes were used to split an address into two components: a network component and a node component. This was later replaced by subnet masking. Similarly, in IPv6, an address is split into two parts. The address is divided 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 top 64-bit segment (network component) is used for routing. The lower 64-bit element (node component) identifies the address of the interface or node. The node component is derived from the actual physical or Mac address using IEEE’s extended unique identifier (EUI-64) format.
The computer network component is split into two blocks of 48 and 16 bits, respectively. The lower 16-bits are controlled by a network administrator and are used for subnets on an internal network. The upper 48-bits are for routing over the internet and are used for the global network addresses.
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3. IPv6 address types and scope
There are three types of IPv6 addresses:
- Global unicast addresses: They are routable on the internet and start with 2001:. The prefix for international unicast addresses comes from what routers convey in their network announcements. They are the same thing as the IPv4 public addresses. SLAAC, which stands for “stateless address autoconfiguration,” needs a block of 64 addresses. Internet authorities give address blocks to Internet service providers (ISPs) so that they can give them to their customers. Currently, the advice is to provide home sites with more than one 64.
- Unique local addresses: These addresses are meant to be used inside an internal network like a local area network. They are routable on the internal network but not on the internet. The address allocation space is segmented into two /8 spaces – fd00::/8 for those globally assigned and fd00::/8 for locally assigned addresses. Organizations can manually set addresses using the prefix fd00.
- Link-local addresses: These addresses are meant to be used as an internal network. They are routable on the internal network but not on the internet. Further, they are analogous to the IPv4 address 169.254.0.0/16, allocated on the IPv4 network without a DHCP server. The link-local addresses start with the prefix fe80. Even if there is no routing, each IPv6 interface has to have a link-local address configured. This is essential.
4. Using IPv6 addresses in uniform resource locators (URLs)
Using an IPv4 network, a user can access a network resource such as a web page using HTTP://192.168.121/webpage. Webpages can also be accessed via IPv6, albeit with a tweak in the format. IPv6 addresses contain a colon as a separator and must be enclosed in square brackets. For instance, HTTP://[2001:db8:4531:674::100e]/webpage.
5. IPv6 loopback
The loopback address represents the same interface as a computer. The TCP/IP protocol stack loops the packets back on the same interface both in IPv4 and IPv6. In IPv4, 127.0.0.0/8 network is reserved for loopback addresses. In IPv6, the loopback address is 0000:0000:0000:0000:0000:0000:0000:0001/128. It can be simplified to::1/128. Not only in IPv4 but also IPv6, routers will not forward packets that have an undefined address. The unspecified address of IPv6 is::/0.
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Features of IPv6
IPv6 has been rethought to overcome the shortcomings of its predecessor, IPv4 while preserving the fundamental capabilities of Internet Protocol (IP) addressing. The following are features of IPv6:
Features of IPv6
1. Larger address space
The main reason IPv6 was developed was to provide a solution for the eventual exhaustion of addresses in IPv4. Unlike its predecessor, IPv6 uses four times more bits to address devices on the internet. These extra bits provide an address space for approximately 3.4 x 10^ 38 devices. Every square meter of our planet has the potential to have around 1564 addresses allocated to it.
Therefore, the larger address spaces provided by IPv6 can meet the aggressive requirements for allocating addresses for almost everything on the planet. More addresses make address conservation techniques such as network address translation (NATs) redundant.
2. Simplified header
The IPv6 header has a new simplified header format designed to be less complex and easier to process than IPv4. The new structure is achieved by moving both optional and non-essential fields of the headers to extension headers appearing after the IPv6 header. The header of the IPv6 is, therefore, only twice more extensive than that of IPv4, even though IPv6 addresses are four times larger.
3. End-to-end connectivity
With IPV6, every machine now has a unique IP address and may traverse the internet without requiring NATs or other translating elements. After the full implementation of IPv6, every host can directly reach other hosts on the internet, but there will be some restrictions in the form of firewalls and organizational policies.
4. Auto-configuration
Auto-configuration not only ensures verification of the uniqueness of a link but also determines the information that should be auto-configured. IPv6 allows stateless address configuration (or no dynamic host configuration protocol DHCP server) and stateful address configuration to ease host setup (as in the presence of a DHCP server).
Hosts on a connection automatically manage IPv6 addresses meant for the link, using addresses generated via prefixes that local routers announce during stateless address settings. Hosts on the same connection may set up themselves using link-local addresses and interact without human configuration in the absence of a router. This ensures that inter-communication goes on regardless of the presence of a server.
5. Faster forwarding or routing
IPv6 features a streamlined header that places all extra information at the end. The information in the front part of the header is enough for quick routing decisions, which makes the routing decision-making process as fast as looking at the mandatory header section.
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6. Stronger security through IPSec
Internet protocol security (IPSec) is currently an optional feature of IPv6. However, the IETF initially decided that IPSec security had to be there to make IPv6 more secure than IPv4. IPSec is used at the network processing layer to secure the network.
7. No broadcast
IPv6 uses a multicast address to communicate with multiple hosts since it does not have any broadcast address support. For one-to-many communication, a multicast address is utilized. It is allocated to a collection of interfaces belonging to several nodes. When IPv6 transmits a payload to a multicast group, it is sent to all interfaces associated with that address. The value of a multicast address begins with “FF” making it easy to identify.
8. Anycast support
The anycast feature provided by IPv6 is the mode of packet routing. It is used for one-to-one-of-many communications. Anycast addresses are allocated to a collection of interfaces belonging to various nodes. Only a single member interface is reached when a packet is transmitted via an anycast address. The member is usually the closest one according to the routing protocol choice of distance.
9. Greater mobility
The mobility feature allows hosts such as mobile devices to remain connected to the same IP address even when roaming in different locations. This is made possible by taking advantage of automatic IP configuration and extension headers.
10. Enhanced priority support
IPv6 uses traffic class and flow label data to inform the underlying router how to process and route the packet efficiently. Routers use flow label fields in the IPv6 header to identify and provide distinct management for packets belonging to a flow. Quality of service (QOS) can be supported even when the packet is encrypted through IPSec because the IPV6 header is the one that identifies the traffic.
11. Smooth transition
IPv6 offers an extensive address system that enables the assignment of universally distinct IP addresses to devices, allowing the devices to communicate and receive data. Routers may also make quicker forwarding choices due to a lighter header.
12. Extensibility
IPv6 can be easily scaled simply by adding extension headers after the existing header. In contrast to IPv4, which could only allow 40 bytes, IPv6 extension headers are restricted solely by the capacity of the IPv6 packet.
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Challenges of IPv6
By 1998, the IETF had formalized the development of IPv6 due to the rapidly decreasing number of IP addresses that IPv4 provided. A couple of decades later, in 2017, the IETF ratified IPv6 as an Internet standard.
The transition from IPv4 to IPv6 is yet to be realized entirely in 2022. With increasing technological advancements, the number of global IPv4 addresses available is nearly depleted, and the need to migrate to IPv6 has become critical. The primary problem with transitioning from IPv6 is that it is not backward compatible with IPv4. Routing and domain name system (DNS) problems occur when using an IPv6 address with a network that only uses IPv4.
The challenges of IPv6 include:
1. Security issues
IPv6 offers many more performance improvements than its predecessor, yet it is still vulnerable. The main security concerns in IPv6 revolve around:
- Header manipulation: Attacks can be based on manipulating headers. Users can minimize them by using IP security or IPSec and extension headers. Nevertheless, these solutions do not always work as specific nodes like firewalls can still be overwhelmed.
- Dual-stacking: When using both IPv4 and IPv6, individual security concerns of the two protocols can be amplified.
- Flooding: With the address of IPv6 being four times bigger than that of IPv4, it takes much more time to scan it. Due to this, smurf-type attacks can be a problem; thus, it is recommended to filter out unnecessary traffic.
- Mobility: The mobility feature in IPv6 exposes it to security concerns such as spoofing attacks. Network administrators can minimize spoof attacks by implementing special security measures to resolve them before they appear.
2. High costs
Due to their incompatibilities, the migration from IPv4 to IPv6 has not been smooth sailing for both organizations and ISPs. Despite being feature-rich, fully upgrading to IPv6 does not have a sufficient return on investment (ROI) to justify the upgrade; hence several ISPs and organizations have opted out. A complete migration requires that all stakeholders put in the necessary infrastructure to keep up with internet best practices, which are impossible due to the high costs involved.
It is expensive to purchase the necessary infrastructure, and organizations and ISPs have to retrain their personnel or hire external experts to bridge the gap. This leads to additional costs.
3. DNS issues
Network connection requires the most basic information, which is the DNS data. With IPv6, this can be a challenge. Configuring a DNS server in an IPv6 network can be complex. This issue is more likely to persist until a consensus is reached on the best way to convey DNS information.
4. Challenges in network adaptation
Although IPv6 is considered the future, many internet service providers (ISPs) don’t yet offer IPv6 services or provide any monitoring support. This is a significant concern as organizations that use IPv6 must seek alternative ISPs that can support IPv6 addressing services. Alternatively, they can get virtual ISPs or use a 6to4 router.
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Takeaway
While IPv6 has been around for a while, it is yet to gain total momentum. IDG, in a recent opinion piece published in August 2022, noted that IPv6 was facing a skills gap with significant differences between adoption regions. Yet, IPv6 is instrumental to the growth of the internet and will play a vital role in emerging use cases like peer-to-peer data transfer and web3. To gain from these technologies, organizations must recognize the importance of IPv6 and prepare for its adoption.
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