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

Yes or no, that's where the classification of IP is. Know or do not know where the subnet mask of IP is. Understand or not, the host bit is still in love with the subnet bit. Sell literary talent to see a smile, hehe. ..

The classification of IP is divided into A, B, C, D, E and so on. If you want to know what they are, go on and I'll give you a description of what I know. An IP consists of two parts, one is the network bit (Network) and the other is the host bit (HOST), the most commonly used are A, B, C three types, A class constitutes the NETWORK HOSTHOST HOST B class NETWORK NETWORK HOSTHOST C class NETWORK NETWORK NETWORK HOST. According to the network bit and host bit, each category has different division rules: class An address 1-126, class B 128-191, class C 192-223 this is the most commonly used, D, E types are applicable in the public network. Types A, B and C are often used in private networks, but which ones are there? Class A: 10.0.0.0-10.255.255.255 Class B: 172.16.0.0-172.31.255.255C 192.168.0.0-192.168.255.255. Class C is the most common and multi-to-many in our work, but how the class C network is formed, or how much can be allocated at most, can be explained below:

Why is subnetting necessary? enter the following reasons:

1. Reduce network traffic no matter what kind of traffic, want it to reduce, network traffic is the same. Without a trusted router, network traffic may bring the entire network to a standstill, but with the router, most of the traffic will stay in the local network, and only packets destined for other networks will pass through the router. Routers add broadcast domains, and the more broadcast domains, the smaller each broadcast domain and the less network traffic per segment.

2. Optimize network performance, which is the result of reducing network traffic.

3. Compared with a large network, it is easier to identify and isolate network problems in a series of connected small networks.

4. WAN links that help to cover large geographical areas are much slower and more expensive than LAN links; a single large-span network may have problems in all aspects, and connecting multiple small networks can improve the efficiency of the system.

The subnet mask is a 32-bit value that allows the recipient of an IP packet to distinguish between the network IP portion of the IP address and the host ID portion.

A network administrator creates a 32-bit subnet mask consisting of 1 and 0, where 1 indicates that the corresponding part of the ip address is a network address or subnet address. Not all networks need subnets, which means that the default subnet mask can be used by default, which cannot be modified, in other words, you cannot set the subnet mask of a Class B network to 255.0.0.0. If you try to do this, the host will consider it illegal and will not allow you to enter it at all. for a Class A network, you cannot tie the first byte of its subnet mask, that is, its first byte must be 255. You cannot set the subnet mask to 255.255.255.255 because it is all 1 and is a broadcast address. The subnet mask for Class B networks must start with 255.255, while the subnet mask for Class C networks must start with 255.255.255.

If subnetting, start with class C. There are many ways to find the one that suits you is the best. In a Class C address, only 8 bits are used to define the host (a total of 32 bits). Note that the subnet extends from left to right and cannot be left blank in the middle (if you do not know the subnet binary to decimal, see the CCNA Learning Guide). It is important to understand and remember the power of 2 in order to subnet accurately and quickly.

How many subnets? 2x, where x is the number of bits covered (with a value of 1). For example, in 11000000, the number of digits with a value of 1 is 2. So the number of subnets is 22 (4).

How many hosts are contained in each subnet? 2y-2, where y is the number of unmasked bits (with a value of 0). For example, in 11000000, the number of bits with a value of 0 is 6, so each subnet can contain 26-2 (62) hosts. The two subtracted are the subnet address and the broadcast address, which are not legitimate host addresses.

What are the legitimate subnets? The block size (increment) is 256-subnet mask. One example is 256-192-64, that is, when the subnet mask is 192, the block size is 64. 6. Increment 64 from 0 until the subnet mask value is reached, and the intermediate result is the subnet, that is, 0, 64, 128, and 192.

What is the broadcast address for each subnet? This is very useful to make sure. The subnet bits 0, 64, 128, and 192 were previously determined, and the broadcast address is always the number of signatures for the next subnet. For example, subnet 0 has a broadcast address of 63 because the next subnet bit 64, subnet 64 has a broadcast address of 127, because the next subnet bit 128, and so on. Remember, the broadcast address of the last subnet is always 255.

Who are the legitimate hosts? Legitimate host addresses are located between two subnets, except for addresses that are all zeros and ones. For example, if the subnet number is 64 and the broadcast address is 127, the legal host address range is 65-126, that is, the number between the subnet address and the broadcast address.

The following exercises can be done according to the following examples.

C Subnet: 255.255.255.128 (/ 25)

Only one bit is used to define the subnet and the remaining seven bits are used to define the host. Here, the Class C network 192.168.10.0 is subnetted.

Network address = 192.168.10.0

Subnet mask = 255.255.255.128

How many subnets are there according to the above prompts? In 10000000, the number of digits with a value of 1 is 1, so the answer is 21. 2. How many hosts per subnet? There are 7 host bits with a value of 0 (100000000), so the answer is 27-2 hosts. What are the legitimate subnets? 256-128. Remember what was mentioned above? The block size is increasing from 0, so the subnets are 0 and 128. What is the broadcast address for each subnet? In the digital clock before the next subnet, all host bits have a value of 1, which is the broadcast address of the current subnet. For subnet 0, the value of all host bits in the number before the next subnet is 1, which is the broadcast address of the current subnet. For subnet 0, the next subnet bit 128, so its broadcast address is 127. What legitimate host addresses does each subnet contain? The legal host address is the number between the subnet address and the broadcast address. The easiest way to determine the host address is to write out the subnet address and broadcast address, and only the legal host address is obvious. About converting binary to decimal, decimal to binary, decimal to hexadecimal, and hexadecimal to binary. These need to check other information, here is a brief mention. Binary conversion hexadecimal: use each bit of binary, four-bit, four-bit division to binary, less than four bits in front of the zero, converted to binary and merged is hexadecimal. Binary to octal: using the number of bits in the binary system, the separation of three bits and three bits, and adding zeros in front of the bits that are less than three bits, and then merging into the binary system is octal. Binary to decimal: multiply each bit by the sum of the power of 2 (bit-1). Hexadecimal to binary can convert each digit to binary. Each number to binary must be four digits less than four digits followed by zeros. Octal to binary is possible to convert each digit into binary, and each data conversion to binary must be less than three digits and be preceded by zeros. The conversion from decimal to binary is divided by decimal by 2 (integer division is 0). 2 is continuously divided by 2 until the remainder is 1 or integral division, and the inverse of the remainder is binary.

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