IPV4 Summarization: IPV4 summarization, also known as route aggregation, is a technique used to combine multiple consecutive IP addresses into a single network address. It helps reduce routing table size and improves overall network efficiency.

IPV6 Summarization: IPV6 summarization, or IPv6 route aggregation, is a method of consolidating multiple consecutive IPv6 addresses into a more concise network address. By using "::" notation and the longest prefix match, it simplifies routing tables and enhances IPv6 network scalability.

The general idea of IPv4/v6 summarisation is to have a single IPv4/v6 subnet that can resolve multiple specific IPv4/v6 network ip address.

Example:

IPv4

20.23.1.0/24

20.23.4.0/25

20.23.6.0/25

20.23.8.0/25

We need to exempt what they have in common from what they don’t have in common starting from left to right.

In our case they have the first and second octet in common.

We can see that the third octet is where we have a change so we will take those decimals and convert them to binaries.

1= 00000000

2= 00000100

6= 00000110

8= 00001000

What they have in common will belong to the network part (so converted to bits on)

and what they don’t have in common will be turned off to represent host bits.

We should have:

0000/0000

0000/0100

0000/0110

0000/1000

——————————

1111/ 0000

What they have in common are turned to bits on (1) and what they don’t are turned to bits off (0)

The bits off will help us find the block size/ increment that is 2 exponent 4 = 16

We will add the first 4 bits turned on to the network part.

We already have a  /16 + 4 bits will be a /20

Hence,

First subnet is 20.23.0.0/20 and  second subnet is 20.23.16.0/20

Technically we can still continue counting our subnets by adding the block-size but based on our context we can stop here because we can find an ip subnet that can resolve all the individual ip subnets we are interested in.

20.23.0.0/20 becomes our summary ip address because in that single subnet we can resolve all our individual ip subnets (20.23.1.0/24 , 20.23.4.0/25 ,20.23.6.0/25 ,20.23.8.0/25 ).

Let’s go to IPv6.

2023:10:172:2B00::A/64

2023:10:172:2C00::B/64

2023:10:172:2D00::B/64

2023:10:172:2E00::B/64

IPv6 uses the 4th hextet to play the role of subnet meaning that’s where we will focus on for our summarisation.

The subnets are:

2B00::/64

2C00::/64

2D00::/64

2E00::/64

We focus on the first position where the  hexadecimal values are different and convert them to binaries.

The second position is where the hexadecimal values are different so let’s convert them to binaries.

B = 1 0 1 1

C=  1 1 0 0

D=  1 1 0 1

E=  1 1 1 0

—————————

    1 0 0 0 >>>>>> they have 1 in common and what they don’t have in common is turned automatically to bits off (0)

When we convert 1000 to hexadecimal we get 8.

So our new subnet will be 2023:10:172:2800::/53

In case you are wondering how we got /53 ?

We summed up the bits ( global routing prefix) of each hextet from left to right as :

2023:10:172:2800

16 bits +16bits +16bits +5 bits = 53

In conclusion, both IPv4 and IPv6 summarization techniques offer significant advantages in terms of optimizing routing tables, reducing overhead, providing IPV4/6 privacy and improving overall network performance.