What Is an IP Address? IPv4 vs IPv6 Explained

Every device connected to a computer network needs a way to identify itself and communicate with other devices. Whether it is an IP camera, PLC, SCADA server, laptop, industrial Ethernet switch, access-control controller or cloud server, network communication depends on addressing.

This is where an IP address comes in.

What Is an IP Address?

An IP address is a logical address assigned to a network interface so that devices can identify the source and destination of IP packets. In simple terms, it works much like an address system for network communication. In simple words we can say,

“An IP address (Internet Protocol address) is a logical numerical identifier assigned to a network interface.”

For Example 192.168.10.25

For business and industrial networks, understanding IP addressing is important because poor IP planning can create duplicate addresses, communication failures, routing problems and difficult troubleshooting.

The two major versions are:

• IPv4 — Internet Protocol version 4
• IPv6 — Internet Protocol version 6

Although IPv4 remains widely deployed, IPv6 was developed to provide a much larger address space and additional capabilities for modern networks.

When one device communicates with another, the IP address helps the network determine where packets should be delivered.

The Ethernet switch handles local Layer 2 forwarding, while IP addressing operates at Layer 3 of the OSI model.

Why Is an IP Address Required?

An Ethernet network can use MAC addresses for local Layer 2 communication, but modern networks require Layer 3 addressing for routing between different networks.

The IP address allows the Layer 3 device to determine that the destination belongs to another network and route the packet accordingly.

This becomes particularly important in industrial environments where separate networks may be created for:

• CCTV
• SCADA
• PLCs
• Access control
• Corporate IT
• Servers
• Network management

What Is IPv4?

IPv4 (Internet Protocol version 4) is the most widely deployed version of IP. IPv4 uses a 32-bit address. The address is normally written as four decimal numbers separated by periods.

For example:

192.168.10.25

Each section is called an octet and can contain a value from 0 to 255.

Because IPv4 uses 32 bits, it provides approximately 4.3 billion possible addresses in the theoretical address space.

However, not all IPv4 addresses are available for assignment to ordinary devices because certain ranges are reserved for private networks, multicast, loopback, special-purpose functions and other uses.

Private IPv4 Addresses

These addresses are not directly routable across the public Internet.

A router performing Network Address Translation (NAT) can allow devices using private IPv4 addresses to access external networks when appropriate.

What Is an IPv4 Subnet?

An IPv4 address is normally used together with a subnet mask or CIDR prefix.

For Example

192.168.10.25/24

The /24 indicates the network prefix length.

In this example, the network is:

192.168.10.25/24

A typical subnet can therefore contain addresses such as:

192.168.10.1
192.168.10.2
192.168.10.3
...
192.168.10.254

The exact usable-host calculation depends on the subnet design and special addresses.

Subnetting is important when designing VLANs because a common architecture associates a Layer 2 VLAN with an IPv4 subnet.

What Is IPv6?

IPv6 (Internet Protocol version 6) was developed primarily to address the limitations of IPv4’s address space.

IPv6 uses a 128-bit address.

Instead of four decimal octets, IPv6 addresses are written using hexadecimal values separated by colons.
The much larger address space provides an enormous number of possible addresses.

IPv6 also includes features such as:

• No requirement for broadcast at the IPv6 protocol level
• Stateless Address Autoconfiguration (SLAAC)
• Link-local addressing
• Multicast-based communication
• Hierarchical addressing
• Neighbor Discovery Protocol

How Is an IPv6 Address Written?

An IPv6 address contains eight groups of hexadecimal digits.

2001:0db8:1234:5678:0000:0000:0000:0010

IPv6 allows certain zeros to be shortened.

The same address can be represented as:

2001:db8:1234:5678::10

The :: represents one or more consecutive groups of zeros.

This makes IPv6 addresses considerably shorter to write than their uncompressed form.

IPv4 vs IPv6: Key Differences

IPv6 is not simply a longer version of IPv4. There are important differences in addressing, neighbor discovery, configuration and network behavior.