IPv4 vs IPv6: What's the Difference?


Posted on July 18, 2018
September 26, 2020

IP (Internet Protocol) is a set of technical rules that defines how networking devices such as computers, laptops or fiber switches locate and communicate over a network. To put the IP address in layman’s terms, you can think of it as your unique digital fingerprint. An IP address is given by the manufacturer and it is embedded in the chip that allows your device to connect to a network. For a fiber switch, it is likely to have multiple IP addresses, since each interface on the switch can be assigned an individual IP address visible to the Internet. There are currently two versions of IP addresses: IP version 4 (IPv4) and IP version 6 (IPv6). What do these terms mean, and what’s the difference between IPv4 vs IPv6?

IPv4 vs IPv6

Figure 1: IPv4 vs IPv6

What Is IPv4?

IP is a Layer 3 protocol, and IP addresses are in the packet headers, which are encapsulated inside the Ethernet frame. IPv4 is the fourth revision of the IP address to uniquely identify devices connected to the network through an addressing system. Whenever a device gets access the Internet (whether it's a switch, PC, Mac or other device), it is assigned a unique, numerical IP address such as as shown below. IPv4 uses 32 bits for its Internet addresses split by dots. That means it can support 2^32 IP addresses in total — around 4.29 billion. That may seem like a lot, but all 4.29 billion IP addresses have now been assigned to various institutions, leading to the crisis we face today. That’s also why the new Internet addressing system, namely IPv6, is being deployed to fulfill the need for more Internet addresses.

What Is IPv4

Figure 2: What Is IPv4 Address

What Is IPv6?

IPv6 is the successor to IPv4. IPv6 was deployed in 1999 in terms of the concern that the demand for IP addresses would exceed the available supply. Thus IPv6 is designed as an evolutionary upgrade to the Internet Protocol and coexists with the older IPv4 until today. IPv6 is a 128-bit IP address written in hexadecimal and separated by colons, which means that IPv6 can support 2^128 Internet addresses in total. IPv6 allows the Internet to grow steadily, both in terms of the number of hosts connected and the total amount of data traffic transmitted. An example of IPv6 address could be written like this: 3ffe:1900:fe21:4545:0000:0000:0000:0000.

What Is IPv6

Figure 3: What Is IPv6 Address

Key Comparisons Between IPv4 vs IPv6

The larger address space is one reason to migrate from IPv4 to IPv6 but there are many other differences that give IPv6 an advantage. For example, IPv6 address is simplified with more efficient routing compared to IPv4 address. The header checksum field has been eliminated in IPv6 as transport reliability has gone up and its overhead was unnecessary. Here are some of the other differences between IPv4 and IPv6 address.

32 bits (4 bytes)
128 bits (16 bytes)
Packet size
576 bytes required, fragmentation optional
1280 bytes required without fragmentation
Packet fragmentation
Routers and sending hosts
Sending hosts only
Packet header
Does not identify packet flow for QoS handling
Contains Flow Label field that specifies packet flow for QoS handling
Includes a checksum
Does not include a checksum
Includes options up to 40 bytes
Extension headers used for optional data
DNS records
Pointer (PTR) records, IN-ADDR.ARPA DNS domain
Pointer (PTR) records, IP6.ARPA DNS domain
IP to MAC resolution
Broadcast ARP
Multicast Neighbor Solicitation
Local subnet group management
Internet Group Management Protocol (IGMP)
Multicast Listener Discovery (MLD)

IPv6 over IPv4 Tunnel

In most cases, IPv6 address and IPv4 address are used separately. However, it is also possible for IPv4 and IPv6 subnets to exchange traffic, namely IPv6 over IPv4 tunnel, but it should depend upon the network configuration and the type of network traffic.

In IPv6 over IPv4 tunnel, you convert IPv6 to IPv4 by encapsulating IPv6 packets in IPv4 packets for delivery across an IPv4 infrastructure (a core network or the Internet). By using overlay tunnels, you can communicate with isolated IPv6 networks without upgrading the IPv4 infrastructure between them. Overlay tunnels can be configured between border routers or between a border router and a host; however, both tunnel endpoints must support both the IPv4 and IPv6 protocol stacks.

convert ipv6 to ipv4

Figure 4: IPv6 over IPv4 Tunnel


The movement from IPv4 to IPv6 on a global scale is inevitable. Although we’re in the transition phase, some experts hold the opinion that IPv6 users take more risks than those who stick to IPv4. Because a tunnel broker is normally used by ISPs to give users on their IPv4 networks access to IPv6 content. Hackers can target IPv6 tunnel users with packet injection and reflection attacks. While some others vote for the newer IPv6 which has larger address space, better routing functionality and more efficiency than IPv4. IPv4 vs IPv6, what is your option? Most routers and switches nowadays have both IPv4 and IPv6 enabled by default. All of FS 10gbe switches and most gigabit Ethernet switches can support both IPv4 and IPv6. They’re with comprehensive protocols to facilitate the rapid service deployment and management for both traditional Layer2/Layer3 networks and fully virtualized data centers.

Related Article: IPv6 Address: Public vs Private