IPv4 vs IPv6 a Complete Guide

Which is better IPv4 or IPv6? What’s the difference between them?? Let’s see:

IPv4 is the most widely deployed Internet protocol used to connect devices to the Internet.

It uses a 32-bit address scheme allowing for a total of 2^32 addresses (just over 4 billion addresses). In the tremendous growth of internet the devices connected to internet is increasing on daily basis! This makes the addresses run out eventually.

Hence forth a new and advanced addressing system was developed and deployed to overcome the outrun which is IPv6 an coexists with IPv4 for some time... 

Fig: IPv4 vs Ipv6 address limitations

IPv6 (Internet Protocol Version 6) is also called IPng (Internet Protocol next generation)

There are some major differences between the two:




Address Size

32 bit

128 bit


Decimal notation

Hexadecimal notation

Prefix (example)


Number of Addresses



Packet Size

576 bytes

1280 bytes

Address mask

Used to designate network from host portion.

Not used

Address types

Unicast address, multicast address, and broadcast address

Unicast address, multicast address, and Anycast address

Address Configuration

DHCP or manual config

DHCPv6/SLAAC(Stateless address auto configuration)

IP header

Variable length of 20-60 bytes, depending on IP options present.

Fixed length of 40 bytes..


TCP and UDP have separate port spaces, each identified by port numbers in the range 1-65535.

For IPv6, ports work the same as IPv4. Because these are in a new address family, there are now four separate port spaces. For example, there are two TCP port 80 spaces to which an application can bind, one in AF_INET and one in AF_INET6.

Other IPv6 advantages over IPv4:

  • No more NAT (Network Address Translation)
  • Auto-configuration
  • No more private address collisions
  • Better multicast routing
  • Simpler header format
  • Simplified, more efficient routing
  • True quality of service (QoS), also called "flow labeling"
  • Built-in authentication and privacy support
  • Flexible options and extensions
  • Easier administration (say good-bye to DHCP)
  • Risks:

  • Security device bypass via unfiltered IPv6 and tunneled traffic
  • Congruence of security policies in v4 and v6
  • Bugs in new code
  • Absence of NAT
  • Source: https://www.networkworld.com/article/2171504/tech-primers/biggest-risks-in-ipv6-security-today.html


    Fig: Growth of IPv6 from its development

    Source: https://www.google.com/intl/en/ipv6/statistics.html

    Interesting Facts about IPv6:

  • Complete transition from IPv4 to IPv6 might not be possible because IPv6 is not backward compatible.
  • Leading zeroes and sometimes Inline zeroes are also suppressed (Used to shorten the length)
  • Link local unicast addresses are easy to identify (Example: local unicast addresses always begin with FE80. Similarly, multicast addresses always begin with FF0x, where the x is a placeholder representing a number from 1 to 8)
  • Loopback address (0000:0000:0000:0000:0000:0000:0000:0001 or ::1)
  • You don't need a traditional subnet mask

    Related Links of Sources and Articles Referred:










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