IPv4 vs IPv6: What is the Difference?

Written by: Maria Kazarez

IPv4 and IPv6 are both versions of TCP/IP protocols. If this sounds like a curse your system administrator used to whisper under their breath, please read on.

IP refers to Internet Protocol, a major part of the Transmission Control Protocol/Internet Protocol Suite (TCP/IP).

TCP/IP is a set of standards and rules regulating the transmission and exchange of packaged data (datagrams) between devices on separate networks. The Internet Protocol governs package addressing, packing/unpacking, and routing efficiency across network boundaries.

To participate in data exchange, each intranet or internet device needs a unique “IP address” – the same way we have our personal “name and address” combination used to receive letters by post. This concerns residential or datacenter proxies, too.

The IP address is included in the standard header of each data package. Without it, it would be impossible to ensure that the packet was delivered to the correct destination or to trace who had sent it.

Internet Protocol is a positive, worldwide standard used by billions of people on several billion devices – including the one you are using to read this. This feels inspiring, doesn’t it?

What Is IPv4?

IPv4 is the first non-experimental Internet Protocol. It was created in the 80s and has received only minor modifications since.

The 4.19 billion unique addresses enabled by IPv4 seemed inexhaustible at the time of its development. No one could anticipate the number of devices we would deal with in everyday life. By the beginning of the 90s, it became apparent that the free IP addresses pool would be used up within two decades.

To extend the life of the IPv4 set of IP addresses, we began to reuse them and implemented solutions like NAT (Network Address Translation.)

The translate-and-forward approach lifted the requirement for a unique IP for each private device: as long as they came with a unique ISP identifier, and this ISP, in turn, did not have duplicate identifiers within its own network, there was no uncertainty about the datagram’s destination.

NAT is a viable solution that is still in wide use today. Its problems are mainly related to security issues, added complexity, errors, and inefficiency. With this nested forwarding approach, one device can’t address another one directly.

What Is IPv6?

It has long been evident that NAT and other measures were only temporary patches: by 2020, the number of connected devices reached 46 billion worldwide – ten times the IPv4 limit.

In 1998, The Internet Engineering Task Force published IPv6, the latest iteration of the Internet Protocol designed to overcome the limitations of the IPv4. IPv6 replaced the IPv4’s 32-bit address with the 128-bit address, which expanded the number of possible unique combinations to about 340 trillion trillion trillion IP addresses.

Both IPv6 and IPv4 are in wide use today. IPv4 remains the prevalent one because of the challenges encountered with the iPv6 adoption.

What are the Advantages and Disadvantages of IPv4?

IPv4 is a historically significant protocol that made our Internet connection and the Internet of Things possible.


  • established, enabled on almost all internet-connected devices, still in wide use;
  • convenient for ISP for traffic control’
  • IP addresses are so simple that you can memorize them.


  • outdated and requires complicated protocols to expand;
  • NAT contradicts one of the original principles of Internet Protocol: end-to-end host connection.

What are the Advantages and Disadvantages of IPv6?

IPv6 is a modern protocol made with more realistic expectations in mind: global networks, streaming, and multiple devices with the same interface. All this was not accounted for when designing IPv4.

The crucial feature of iPv6 is that it restores the core principle of IP lost to IPv4 address shortage. The device can now have a globally unique address again, which means a direct device-to-device connection without complications of the translation system.


  • the number of unique addresses will not be exhausted anytime soon;
  • it is easier to make it private as long as it is implemented correctly;
  • efficient and logical hierarchical addressing and routing infrastructure;
  • stateful and Stateless configuration for different use cases;
  • better error control techniques;
  • no address translation protocols means easier source tracing, which brings more transparency. Theoretically, simpler routing also means fewer opportunities to tamper with the data during its transmission;
  • the router’s task is simplified – no more private network identifier conflicts;
  • better compatibility with mobile networks;
  • improved bandwidth efficiency when streaming to multiple devices.


  • IPv6 did not come with backward interoperability: a device that is only IPv4-enabled cannot connect to the device with an IPv6 address;
  • it can be expensive to implement for big organizations and ISP, as it does not support gradual transition well.

The Difference Between IPv4 and IPv6

 IPv4 VS IPv6

IPv6 is not just a newer version of its predecessor, IPv4. It is an entirely different design. The “length” of the unique name is not the only difference: attributes and the way to manage names are new, too.


iPv4 IPv6
Published 1978, Deployed 1981 Published 1998, Deployed 2021
32-bit address. Attributes: the network prefix and host address. 128-bit address. Attributes: interface identifiers (the last 64 bits), scope, the lifetime of the package, etc. 
4.19 billion possible addresses 340 trillion trillion trillion addresses
Top-level free pool exhausted by 2011 Wide pool available
A single address per interface Often multiple addresses with different purposes for a single interface. 
A few global public addresses for special uses Vast number of global public addresses for most needs
Difficult to change the device’s address over time Easy to change the device or the network address over time
Address looks like Address looks like fe80::d4a8:6435:d2d8:d9f3b11
Mostly manual network configuration Auto-configuration and manual network configuration
Very hard to secure transmission end-to-end because of indirect connection Allows to secure transmission end-to-end
Broadcast and optional multicast  Multicast only
Header error check by checksum Multiple error checks without checksum
576 bytes packet size 1280 bytes packet size
Packet fragmentation by the host or by router Packet fragmentation by the host
No Quality of Service customization QoS customization instructions


IPv4 vs IPv6: Which is Faster? Which is Safer? 


Is IPv6 more secure than IPv4? Is IPv4 more secure than IPv6? 

Neither is correct. IPSec is a stack of authentication, encryption, security, privacy, and data integrity security protocols built into IPv6. Theoretically, the newer and more sophisticated approach of IPSec IPv6 has advantages over IPv4 IPSec. Using IPsec end-to-end in IPv6 is significantly easier than in IPv4, albeit it is still not mandatory.

In reality, for both versions, the main risks are associated with imperfect implementation and the human factor, not the security measures design. In addition, since many devices and operating systems have both IPv4 and IPv6 protocols enabled, they have the vulnerabilities of both. 

Is IPv6 Faster Than IPv4? Or the Opposite?

The speed difference is insignificant except for some niche use cases like Xbox online gaming. 

In theory, IPv6 is expected to be slightly faster since the transmission does not have to waste time on NAT translations. However, IPv6 also has larger packets and can include special package handling instructions, potentially making it slower. 

IPv6 is 20 Years Old, yet IPv4 is Still in Use. Why? 

The situation with the technology shift is different in consumer devices and business systems. 

The majority of 10-years-old computers, routers, and phones already have IPv6 support. Most other devices can get a firmware upgrade to include it. 

It is not the same for organizations with massive networks. Transition to IPv6 will have to happen, but this migration is extremely resource-demanding and requires extensive planning and personnel re-education. Many businesses employ IPv6-capable Proxy providers for business as the interim solution.

Internet Service Providers face the same “business sense” conflict. In addition to resources-related problems, ISP will lose some of the current traffic control capabilities. And the improvement is hard to market to the general public. So it is not surprising that community-serving ISPs struggle to justify switching to IPv6. 

What Happened to IPv5?

IPv5 was abandoned at the draft stage. It used the same 32-bit addressing design, and it would have faced the same limitation as IPv4. 

IPv6 is the next iteration of IPv4, a natural product of technological evolution. It faces the same challenges as any significant innovation. The challenge of the progress is to find a way to move forward toward better security, privacy, and simplicity without abandoning those who cannot make a switch. 

Finding that balance is not easy, regardless of the industry. But you can take your time learning from the transition experiences of others and experimenting. IPv4 will stay with us for a while. IPv6 will continue to gain ground. And advanced Proxies are already capable of IPv4, IPv6, or both. 

Maria Kazarez

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