Understanding IPv4 versus IPv6 is no longer just a technical detail for network engineers. It has practical consequences for businesses, developers, and anyone running online services.

What Is IPv4?

IPv4, or Internet Protocol version 4, is the original addressing system of the modern internet. It was introduced in the early 1980s and remains widely used today.

A typical IPv4 address looks like this:

192.168.1.1

It consists of four numbers separated by dots, each ranging from 0 to 255. This structure allows for about 4.3 billion unique addresses.

At the time IPv4 was designed, that number seemed more than sufficient. The internet was small, academic, and experimental. No one anticipated billions of smartphones, cloud servers, and connected devices competing for addresses.

Why IPv4 Became a Limitation

As the internet expanded, IPv4 addresses began to run out. By the early 2010s, the global pool was effectively exhausted.

To delay the problem, technologies like Network Address Translation (NAT) were introduced. NAT allows many devices to share a single public IP address. While effective, it adds complexity and breaks the original end-to-end design of the internet.

IPv4 still works, but it survives through workarounds rather than clean architecture.

What Is IPv6?

IPv6, or Internet Protocol version 6, was designed specifically to solve IPv4’s limitations.

An IPv6 address looks like this:

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

It uses hexadecimal numbers and colons and is much longer than IPv4. That length exists for one reason: scale.

IPv6 provides an almost unlimited number of addresses. In practical terms, address exhaustion is no longer a concern.

IPv6 was created not just as a bigger version of IPv4, but as a protocol designed for modern networking. It assumes massive device counts, automated configuration, and long-term growth.

Core Differences Between IPv4 and IPv6

Address Capacity

This is the most fundamental difference. IPv4 has a fixed and limited address space. IPv6 removes that limitation entirely.

With IPv6, every device can have its own globally unique address without sharing or translation. This changes how networks are designed and managed.

Address Format and Readability

IPv4 addresses are short and easy to recognize. IPv6 addresses are longer and less human-friendly, but that matters less in practice.

Most modern systems rely on DNS, automation, and software tools rather than manual address entry. The complexity is handled by machines, not people.

NAT and Network Design

IPv4 depends heavily on NAT. IPv6 does not require it.

Removing NAT simplifies:

• Peer-to-peer connections
  
• Real-time communication applications
  
• Network troubleshooting and monitoring
  

This is especially relevant for gaming, VoIP, video conferencing, and IoT environments where direct connectivity matters.

Configuration and Automation

IPv6 was designed with large-scale automation in mind. Devices can configure themselves using Stateless Address Autoconfiguration (SLAAC), often without manual intervention.

IPv4 networks can be automated too, but they rely more on centralized services like DHCP and careful address planning. IPv6 reduces that overhead, particularly in large or dynamic environments.

Security Considerations

IPv6 was built with modern security assumptions. Support for IPsec is part of the protocol specification, and the absence of NAT makes end-to-end encryption more straightforward.

That said, IPv6 is not automatically secure. Poor configuration can still expose systems. The difference is that IPv6 removes structural obstacles that made secure design harder in IPv4-centric networks.

Why IPv6 Matters Today

IPv6 is often described as “the future,” but in reality, it’s already in active use.

IPv4 Is Becoming a Bottleneck

IPv4 addresses are now scarce assets. Internet providers buy, sell, and reuse them aggressively. This increases costs and adds operational complexity.

Large-scale NAT introduces latency, connection limits, and debugging challenges. As traffic grows, these issues become harder to ignore.

IPv6 avoids these problems rather than masking them.

Mobile and ISP Networks Already Rely on IPv6

Many mobile networks use IPv6 as their primary protocol, with IPv4 running through translation layers in the background.

If an application or service behaves poorly over IPv6, users may already be experiencing issues without realizing why. Supporting IPv6 is no longer optional for mobile-friendly infrastructure.

Cloud and IoT Growth Depends on IPv6

Modern infrastructure scales differently than traditional networks. Cloud platforms, containers, and IoT deployments benefit from having vast numbers of unique addresses.

IPv6 enables:

• Cleaner service discovery
  
• Simpler network segmentation
  
• Better visibility at scale
  

These advantages become more important as systems grow larger and more distributed.

Performance and Routing Efficiency

In many environments, IPv6 traffic takes more direct routes and avoids translation overhead. This doesn’t guarantee faster speeds, but it removes common friction points found in IPv4-heavy setups.

Over time, as IPv6 adoption increases, performance consistency becomes another reason to support it properly.

Why IPv4 Is Still Around

Despite its limitations, IPv4 is deeply entrenched. Legacy hardware, outdated software, and incomplete IPv6 support keep it alive.

Most networks operate in dual-stack mode, running IPv4 and IPv6 side by side. This coexistence will likely continue for years, if not decades.

IPv4 isn’t disappearing overnight. But it’s no longer the protocol shaping the future.

Final Thoughts

IPv4 built the internet we know today, but it was never designed for the scale and complexity of modern connectivity. IPv6 addresses those limits directly instead of working around them.

The transition is gradual and often invisible, but it’s happening everywhere – in mobile networks, cloud platforms, and new infrastructure.

IPv4 keeps the internet running.
IPv6 keeps it growing.

Understanding the difference is no longer optional. It’s part of operating in today’s internet, not tomorrow’s.

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Like UDP, TCP uses the IP protocol as a lower-level protocol for transmitting datagrams and supports the transmission of a continuous stream of datagrams. But unlike UDP, TCP provides reliable delivery of messages. TCP guarantees that during transmission the data will not be distorted, lost, copied, and their order will not be changed. It allows programmers not to build special mechanisms of protection of transfer of data in the applied programs.

The features of TCP protocol are listed below:

Simple data transmission.

TCP supports bidirectional transfer of continuous data octets between users, dividing data on segments which are transferred through the Internet. The minimum size of a TCP segment is 1024 bytes. In the general case TCP itself decides when to transmit a block of packets.

Reliability

TCP corrects the errors connected with the distortion, loss, duplication of the data, and also change of an order of delivery. To do this, TCP assigns a sequence number to all data octets and waits for an acknowledgement (ACK) on the delivery of each octet from the TCP target module. If the timeout has expired before the ACK is received, the data is retransmitted. The TCP retransmission timeout value for each connection is determined dynamically based on a cyclic time counter. Sequential numbers allow the destination TCP module to restore the order of data received and to remove duplicate packets. Data integrity is checked using a checksum, which is calculated by the sender for each segment transmitted and checked by the recipient, which discards damaged segments.

Flow control

To control the flow in each ACK packet, the TCP module specifies the recipient window size, that is, the allowable interval of message sequence numbers following the last successfully received data segment. The window size specifies the number of octets that the sender can transmit until the next permission is received.

Multiplexing

TCP allows multiple host processes to simultaneously work with TCP functions. Each host is allocated a set of ports for TCP. A unique TCP socket identifier consists of the port number, network address, and host address. Each connection is uniquely identified by a socket pair.

Connections

TCP stores certain state information for each data stream to transmit. This information forms the description of the connection and contains information such as the socket pair, sequence numbers of segments, and window size. A pair of sockets located at different ends of a connection uniquely identifies that connection.

Priority and protection

The TCP user can set the security level and priority of the data being sent. If the user does not specify custom values, default values apply.

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The four layers of the TCP/IP model:

• The data link layer: defines how data is transmitted, handles the physical action of sending and receiving data, and is responsible for transferring data between applications or devices on the network. It involves determining how data should be transmitted by hardware and other transmitting devices on the network, such as a computer device driver, Ethernet cable, network interface card (NIC), or wireless network. It is also called the data link layer, network access layer, network interface layer, or physical layer and is a combination of the physical and data link layers of the OSI network model, which standardizes communication functions in computing and telecommunications systems.
• Internet layer: is responsible for sending packets from the network and managing their movement through the network to ensure they reach their destination. It provides functions and procedures for transmitting data sequences between applications and devices over networks.
• Transport layer: is responsible for ensuring a reliable data connection between the source application or device and its intended destination. This is the layer where data is divided into packets and numbered to create a sequence. The transport layer then determines how much data should be sent, where it should be sent, and at what rate. It ensures that data packets are sent error-free and consistently and receives confirmation that the target device has received the data packets.
• Application layer: refers to programs that need TCP/IP to provide their message. This is the layer that users typically interact with: for example, e-mail systems and messaging platforms. It combines sessions, presentations and applications of the OSI model.

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TCP/IP divides communication tasks into layers that support standardization of the process, without the need for hardware and software management on its own. Data packets must pass through four layers before they are received by the target device, then TCP/IP passes through the layers in reverse order to return the message to its original format.

As a connection-oriented protocol, TCP establishes and maintains a connection between applications or devices until they have finished exchanging data. It determines how the original message should be broken down into packets and numbers, reassembles the packets, and sends them to other devices on the network, such as routers, security gateways, and switches, and then to their destination. TCP also sends and receives packets from the network layer, handles the transmission of any lost packets, manages the flow, and ensures that all packets reach their destination.

A good example of how this works in practice is sending an email using SMTP from an email server. The TCP server layer divides the message into packets, numbers them, and forwards them to the IP layer, which then forwards each packet to the destination e-mail server. When the packets arrive, they are sent to the TCP layer to be reassembled into the original message format and forwarded to the e-mail server, which delivers the message to the user’s mailbox.

TCP/IP uses a three-way handshake to establish a connection between the device and the server, allowing multiple TCP socket connections to be sent simultaneously in both directions. The device and the server must synchronize and acknowledge packets before communication can begin, after which they can negotiate, share, and transmit TCP socket connections.

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Transmission Control Protocol (TCP) is a communications standard that allows application programs and computing devices to exchange messages over a network. It is designed to send packets over the Internet and ensure the successful delivery of data and messages across networks.

TCP is one of the main standards defining the rules of the Internet and is included in the standards defined by the Internet Engineering Task Force (IETF). It is one of the most commonly used protocols within digital networking and provides end-to-end data delivery.

TCP organizes data so that it can be transmitted between the server and the client. This ensures the integrity of the data transmitted over the network. TCP establishes a connection between a source and its destination before data is transmitted, which ensures that it functions before the data is exchanged. It then breaks up large amounts of data into smaller packets, ensuring data integrity throughout the process.

As a result, TCP is used to transfer data from high-level protocols that require all data to be received. Such protocols include File Transfer Protocol (FTP), Secure Shell (SSH), and Telnet. It is also used to send and receive e-mail through the Mail Access Protocol (IMAP), the Post Office Protocol (POP), and the Simple Mail Transfer Protocol (SMTP), as well as to access the Internet through the Hypertext Transfer Protocol (HTTP).

An alternative to TCP is the User Datagram Protocol (UDP), which is used to establish low-latency connections between applications and speed up transmission. TCP can be an expensive networking tool because it includes missing or corrupted packets and protects data delivery with controls such as acknowledgement, connection triggering, and flow control.

UDP does not provide a faulty connection or packet sequence, nor does it signal the destination before the data is transmitted, which makes it less reliable but also less expensive. Thus, it is a good option for situations where time is important, such as domain name system (DNS) lookups, IP telephony, and streaming media.

What is IP?

Internet Protocol (IP) is a method of transferring data from one device to another over the Internet. Each device has a unique IP address defining it, which allows it to exchange data with other devices connected to the Internet.

The IP address is responsible for determining how applications and devices exchange data packets with each other. It is the basic communication protocol responsible for the formats and rules for exchanging data and messages between computers on one or more networks connected to the Internet. This is accomplished by the Internet protocol suite (TCP/IP), a group of communication protocols divided into four levels of abstraction.

IP is the basic protocol at the TCP/IP Internet layer. Its main purpose is to deliver data packets between a source application or device and a destination using methods and structures that place tags, such as address information, in the data packets.

TCP or IP: what’s the difference?

TCP and IP are separate protocols that work together to ensure that data is delivered to its intended destination on the network. IP receives and determines the address (IP address) of the application or device to which the data is to be sent. TCP is also responsible for transmitting the data and ensuring that it is delivered to a specific IP device or target application.

In other words, the IP address is the same as the phone number assigned to the smartphone. TCP is the computer network version of the technology that activates a smartphone call and allows the user to talk to the caller. The two protocols are often used together and rely on each other for data to have a destination and reach it safely, so the process is often called TCP/IP.

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DARPA (Defense Advance Research Projects Agency) has developed TCP/IP (Transmission Control Protocol/Internet Protocol) to network computers from different departments of the US Department of Defense.

International distributed network Internet uses a stack of protocols TCP / IP for connecting computer resources around the planet. Quite often these protocols are also used in private and commercial networks.

The TCP/IP stack includes the following protocols:

IP/IPv6 – Internet Protocol.

TCP – Transmission Control Protocol.

UDP – User Datagram Protocol.

Link Layer

ARP/RARP – Address Resolution Protocol/Reverse Address.

Tunneling protocols

ATMP – Ascend Tunnel Management Protocol.

L2F – Layer 2 Forwarding Protocol.

L2TP – Layer 2 Tunneling Protocol.

PPTP – Point-to-Point Tunneling Protocol.

Network Layer

DHCP / DHCPv6 – Dynamic Host Configuration Protocol.

DVMRP – Distance Vector Multicast Routing Protocol.

ICMP /ICMPv6 – Internet Control Message Protocol.

IGMP – Internet Group Management Protocol.

MARS – Multicast Address Resolution Server.

PIM – Protocol Independent Mulyicast.

RIP – Routing Information Protocol.

RIP2 – Routing Information Protocol II.

RIPng for IPv6.

RSVP, Resource ReSerVation setup Protocol.

Security

AH – Authentication Header.

ESP – Encapsulating Security Payload.

Routing

BGP-4 Border Gateway Protocol.

EGP – Exterior Gateway Protocol.

EIGRP – Enhanced Interior Gateway Routing Protocol.

GRE – Generic Routing Encapsulation.

HSRP – Cisco Hot Standby Router Protocol.

IGRP – Interior Gateway Routing.

NARP – NBMA Address Resolution Protocol.

NHRP – Next Hop Resolution Protocol.

OSPF – Open Shortest Path First.

Transport Layer

Mobile IP.

Van Jacobson – compressed TCP.

XOT – X.25 over TCP.

VoIP

MGCP – Media Gateway Control Protocol.

SGCP – Simple Gateway Control Protocol.

Session Layer

DNS – Domain Name Service.

NetBIOS/IP.

Application layer

FTP – File Transfer Protocol.

Finger User Information Protocol.

TFTP – Trivial File Transfer Protocol.

Gopher – Internet Gopher Protocol.

HTTP – Hypertext Transfer Protocol.

S-HTTP – Secure Hypertext Transfer Protocol.

IMAP4 – Internet Message Access Protocol rev 4.

IPDC – IP Device Control.

ISAKMP – Internet Message Access Protocol rev 4rev1.

NTP – Network Time Protocol.

POP3 – Post Office Protocol rev 3.

Radius .

RLOGIN – Remote Login.

RTSP – Real-time Streaming Protocol.

SMTP – Simple Mail Transfer Protocol.

SNMP – Simple Network Management Protocol.

TACACS+ – Terminal Access Controller Access Control System.

TELNET .

X-Window .

Translated with www.DeepL.com/Translator (free version)

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