What is the difference between IPv4 and IPv6?

What is the difference between IPv4 and IPv6?

IPv6 (IP version 6), defined in RFC 2460, is the most recent generation of the Internet Protocol (IP) defined by the Internet Engineering Task Force (IETF). The first stable version of Internet Protocol (IP) was IPv4 (IP version 4). Whereas IPv6 is intended to eventually replace IPv4, they are tightly mingled right now—most engineers run them together.

Benefits of Using IPv6

The IP layer of the TCP/IP protocol stack is the most crucial piece of the whole Internet architecture. However, within ten years of IP going mainstream in the 1980s, the limitations of IPv4 in terms of scalability and capability became obvious. IPv4 requires several add-ons like ICMP and ARP to function. By the mid-1990s, a replacement scheme was developed. The move to IPv6 is necessary to accommodate the explosion of Internet requirements, Internet technology profile mandates that access via IPv4 and access via IPv6 have to coexist.

IPv6 offers these improvements over IPv4:

  • More efficient routing without fragmenting packets
  • Built-in Quality of Service (QoS) that distinguishes delay-sensitive packets
  • Elimination of NAT to extend address space from 32 to 128 bits
  • Network layer security built-in (IPsec)
  • Stateless address auto-configuration for easier network administration
  • Improved header structure with less processing overhead

How Do IPv4 and IPv6 Work?

  • The 128-bits in the IPv6 address are eight 16-bit hexadecimal blocks separated by colons. For example, 2dfc:0:0:0:0217:cbff:fe8c:0.
  • IPv4 addresses are divided into “classes” with Class A networks for a few huge networks, Class C networks for thousands of small networks, and Class B networks that are in between. IPv6 uses subnetting to adjust network sizes with a given address space assignment.
  • IPv4 uses class-type address space for multicast use ( IPv6 uses an integrated address space for multicast, at FF00::/8.
  • IPv4 uses “broadcast” addresses that forced each device to stop and look at packets. IPv6 uses multicast groups.
  • IPv4 uses as an unspecified address, and class-type address ( for loopback. IPv6 uses :: and ::1 as unspecified and loopback address respectively.
  • IPv4 uses globally unique public addresses for traffic and “private” addresses. IPv6 uses globally unique unicast addresses and local addresses (FD00::/8).

Juniper Networks Implementation

Juniper Networks complies with RFC 5952 in the standard assignment and display rules for IPv6 addresses. These rules mean that devices must accept all methods of address entry.

Junos Address Aware is an addressing and tunneling software portfolio for the MX Series routers that helps network operators conserve and extend their IPv4 address pool, ensure IPv4/IPv6 coexistence, and pragmatically transition to IPv6.


Practical Resources

Technical Documentation