On the dawn of a new age in the world of computer networking, IPv4 addressing is slowly running out of time and “space” in a growing world population which means making room for the next generation of IPv6 addressing. Learn more on the differences between IPv4 vs IPv6 addresses and how IPv6 addresses will make availability easier for small business and large organizations in the world.
Limitations of IPv4 Routing
Before diving into why IPv6 routing is the future of networking, we’ll first look into what IPv4 offers and why there are limitations.
IPv4 addresses first off is not meant to be “permanent” IP addresses for the reason that IPv4 addresses are leased from a Dynamic Host Configuration Protocol server which means the addresses are assigned by the Internet Service Provider (ISP) through DHCP in order to have each device configured.
In addition, the ISP would retrieve a pool of IPv4 addresses from a national or local registry maintained by the Internet Assigned Numbers Authority.
Bringing me to the first limitation of IPv4 routing, the IPv4 address is a considered a “temporary” device ID that can be changed to a new address at anytime whether there is a change in the LAN/WAN or simply when a local user requests a new address like in situations of being DDoS’ed.
The second major limitation of IPv4 routing is there is not enough available addresses to compensate the high number of computers, laptops, routers, and switches used in large subnet networks reserved by organizations down to small office home office devices used in a typical home LAN.
There is only 4,294,967,296 available IPv4 addresses (232) and with roughly more than 7.8 billion people in the world population (as of 2020), the IPv4 address availability is 55% less than the world population that’s if everybody used some form of technology.
The last major limitation to list with IPv4 routing lies within the technical specs in which it’s not the best for memory and processing benefits since the routing table within a network can expand when routes are added that could mean more time it takes for a router to learn best possible path when using a protocol like OSPF (Open Shortest Path First) protocol.
Growing Concerns of IPv4 Address Availability
The one question every technology newbie may ask is: Why is IPv4 address availability becoming more limited?
The answer is simply because of “wasted” address space as a result of improper subnetting of a network to reserve more IPv4 addresses than what is needed.
In other undeliberate cases where there is not a precise prefix length (this can be /24, /16, and so on!) to obtain the exact number of subnets needed to accommodate the exact number of hosts a company has…regardless there would still be address space even if there is 3 or 4 addresses unused in the final subnet pool.
Lifelines of IPv4 Routing
Despite IPv4 routing being nearly 40 years old, IPv4 has been on “life-support” because of Variable-Length Subnet Masks (VLSM), Network Address Translation (NAT), and the usage of private IPv4 addresses.
VLSM improved on the usage of Fixed-Length Subnet Masks (FLSM) by incorporating a process of creating a number of subnets in different sizes to make the use of IPv4 addresses achieve efficiency by assigning the largest subnet from the start of the address space first and going down the line until all subnets have been assigned.
NAT on the other hand of playing a role in IPv4 routing translates between public and private IP address to enable hosts on a privately addressed network access a public network such as the Internet.
NAT provides a 1:1 ratio of mapping IPv4 addresses on the inside network and configures with a pool of public IP addresses when multiple internal hosts require simultaneous access to the external public network…overall NAT prevents overlapping of a IPv4 addresses when hosts in different networks with the same IP address try to reach a destination.
On point with NAT, IANA reserves private IPv4 address types for major corporations that rely on them for “internal usage” since they are not directly connected to a public network.
Even home networks start with a private IPv4 address, converts to a public IPv4 address to send packets out on the Web, and then reverts back to a private IPv4 address when packets are sent back to the home router.
IPv6 Addresses: The Future of Networking
Going from IPv4 to IPv6 addresses, IPv6 routing improves on the 32-bit IPv4 routing by using a 128-bit hexadecimal format with the ultimate factor that every bit used in an IPv6 address would double the number of possible addresses IPv4 couldn’t…making it the “next generation” Internet Protocol.
There is about 340 undecillion possible addresses (the exact number of IPv6 addresses is actually 340,282,366,920,938,463,463,374,607,431,768,211,456 or 2128…easier for somebody else to say) which is more than enough to compensate the world population by about a 1000 times more than IPv4.
When IPv6 was developed in 1998, the Internet Engineering Task Force (IETF) made sure the ultimate benefit of IPv6 routing is it would be “permanent” solution that should not require the usage of a DHCP server in order to be leased to a network host…the addresses basically configure themselves automatically
Another benefit of IPv6 routing is the simplicity and efficiency of only using 8 fields in the packet header since the processing of IPv6 headers take less time to compute in routers handled by the processor and data…less time means less overhead.
In addition to faster processing, IPv6 routing does not break down IP packets down into fragments like IPv4 to meet maximum transmission unit sizing. Instead, IPv6 delegates end-point MTU size via Path MTU Discovery to making sure the packet is smaller than the MTU to go through the path traveled on the route.
Finally, security is built into IPv6 routing where it works hand-in-hand with IPSec as a potential security protocol to secure communication flows at the IP layer between end hosts; but, IPSec must use Internet Key Exchange version 2 (IKEv2) to work within the native IP stack in the gateway.
Why IPv6 addresses are not a Priority?
We mentioned above that NAT is one of the reasons that IPv4 is still around in modern network because it has slowed the implementation of IPv6; but, there is one more reason why IPv6 routing is not necessary to be used today.
This other reason is because of the factor in “backwards compatibility” if a website or intranet site is built on IPv6 and trying to access this site from only a IPv4 compatible device then it’s not going to work.
The same compatibility issue proves true with routers, modems, VoIP phone systems, and home surveillance systems may not support IPv6 and would require replacement when the time comes to fully roll out IPv6 routing.
Another issue in IPv6 routing is the issue of traversing traffic between the two IP protocol types or running a dual-stack network design which can be complex to maintain if you’re a network engineer with an ISP or major corporation.
Setting up dual stacks to transverse traffic could prove less than desirable performance results when trying to implement dual domains that use both IPv4 and IPv6 since there could be bottlenecks.
