Shulou(Shulou.com)06/01 Report--

IP Subnetting for Advanced computer Network

First of all, we need to know something about the IP address. Please refer to (https://blog.51cto.com/14557673/2441411)

On this basis, we begin to discuss the following three questions: what is IP subnetting, why subnetting and how to subnetting.

What is subnetting?

First of all, we can understand the concepts of proper nouns such as subnets, masks, classful addresses and classless addresses in Baidu encyclopedia. So what exactly is subnetting?

The answer is to further divide the various IP addresses into smaller networks. For example, it is impossible for us to need a lot of ip addresses at home, so operators will assign a small segment of ip addresses to users.

Save resources and save costs.

Second, why subnetting?

The above example has already given the answer, which is to increase the utilization of network ip addresses, reduce the broadcast range, and make it easier to manage.

Third, how to subnetting?

This problem is the core one.

First of all, let's give a common example to illustrate that we usually use a class C address, which is the type address of 192.168.XXX.XXX. Suppose an address is 192.168.10.177, normally looking at its subnet mask

It is 255.255.255.0. According to the subnet mask, we know that the binary of the first three parts (the network part) is 1 of 24 bits, so it is usually written as 192.168.10.177max 24 when subnetting, so for it

Subnetting is borrowing from the host bit, and each borrowing bit divides the host part into 2 ^ n (n represents the number of borrowed bits). 192.168.10.177Compact 26, which divides it into four parts, so where is the ip address

The range of 192.168.10.128 is 192.168.10.223, where 192.168.10.128 is the subnet address (network number) and 192.168.10.223-bit broadcast address, which corresponds to our normal ip address

192.168.10.0 and 192.168.10.255. In fact, the addresses of other classes are the same principle, except that the number of borrowed digits may exceed 8 bits, which can actually be regarded as subnetting the corresponding addresses of other classes.

Let's talk about what is subnet summary.

Again, in the above example, 192.168.10.177Universe 23, the subnets are aggregated (aggregated). We can look at this situation like this:

192.168.10.177 binary is: 1100 0000.1010 1000.0000 1010.1011 0001

So / 23 is to change the last bit of the third part into the content of the host part, so the first 23 bits remain unchanged.

In fact, to put it simply, how many bits are added to the front is to divide it into 2 ^ (8Mutual) parts, so the above example is divided into 128 parts, the corresponding subnet address is 192.168.10.0, and the broadcast address is

192.168.11.255.

The advantage of summarization is that routing or switch can avoid the waste of resources in storing relevant information, and greatly improve the efficiency of communication.

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