In depth good article: what is supernetting?

Hypernets are the opposite of subnets , In subnet partition , A large network is divided into several smaller subnets , In the Supernet , Multiple networks are combined into a larger network , It is called a hypernetwork or

HYPERNET

.

Hypernets are generally used for route aggregation , Combine the routes of multiple networks with similar network prefixes into one route entry , The route entry points to a super network , Include all networks . This has the advantage of significantly reducing the size of the routing table and the size of the routing updates exchanged by the routing protocol .

Let's learn more about ！

What is Supernet ？

Everyone is familiar with subnets ： Decompose a larger network into smaller networks .

The subnet has a twin sister ： HYPERNET , Just the opposite , Aggregate the network into a larger network .

The English name of HYPERNET ：

Supernetting

.

The role of HYPERNET

The routing table contains subnet mask entries for each network , If there are many small networks , The size of the routing table will increase , When the router has a large routing table , It takes a long time for the router to process the routing table , Hypernets are used to reduce  IP  Size of routing table , To improve network routing efficiency .

Supernet address

HYPERNET uses no class  Internet  Domain routing  (CIDR), This concept of address management is not unique to HYPERNET , It is also widely used in subnet partition .

CIDR  Deploy “ Variable length subnet mask ”（VLSM）, This is the efficient use of address space , It also reduces the network exhaustion caused by a wide range of address errors allocated to all network segments  IP  Probability of address .

Rules for HYPERNET aggregation

For any network to aggregate , All should follow three rules ：

• continuity
  ： All networks should be continuous .

• Same size
  ： All networks should be the same size , And is  2  The power of , namely  2^n.

• Divisibility
  ： first  IP  The address should be divisible by the entire Supernet size .

Example of super network

There is a set of networks ：

• 172.16.0.0/24

• 172.16.1.0/24

• 172.16.2.0/24

• 172.16.3.0/24

Before aggregation , Let's take a look first , Whether the above rules for hypernetwork aggregation are met ：

1、 continuity

We see that all four networks are C Class address , The scope of the first network is ：

172.16.0.0

To

172.16.0.255

, The scope of the second network is

172.16.1.0

To

172.16.1.255

, We noticed that , The last of the first network IP Address +1 Is the first address of the second network , Meeting aggregation rules “

Continuity

”.

2、 Same size

All four networks are C Class address , The subnet masks are 24 position , The number of hosts is 2^8 namely 256 individual , Therefore, it also satisfies the second attribute of the HYPERNET aggregation rule ：

Same size

.

3、 Divisibility

We can see that the network address size of the whole Supernet is 4*2^8, namely 2^10 individual , If the first one  IP  At the end of the address  10  Bit is zero , be  IP  Divide divisible .

first  IP  At the end of the address  10  Bit is zero , The red part , therefore , It also meets the condition of the third hypernetwork aggregation ：

Divisibility

.

Finally, the four networks can be aggregated ！

First, let's look at the binaries of the four networks ：

By determining which bits of them are common and setting all other bits from that point to  0  To aggregate the network .

These four networks go all the way to the  22  Block （ from  1  Start counting from the left ） It's all the same , The first  23  Blocks are the difference （ Highlighted in orange ）, therefore , The subnet mask of the new Supernet will always be  1  To the first  22  Block , Then from there for  0：

The Supernet address is

172.16.0.0 255.255.252.0

, namely

172.16.0.0/22

.

The above is an example of hypernetwork aggregation , Is it simple ！