Subnet mask calculation and division

[Osman84]

Hi all,

Internet work-scale model of the rapid expansion of the IP address of the threat is not that it can not guarantee the uniqueness of the host address, it would result in two burdens: first, the huge network address management overhead; second, gateway rapid expansion of routing. Therefore, an urgent need to find new technologies to meet the net growth between the size of the network problems. Careful analysis found that net growth between the size of the network is manifested mainly in the internal network address change, so the idea of problem-solving focused on: how to reduce the network address. So the multiple IP network address multiplexing emerged. Through multiplexing, so that a number of physical network share the same IP network address, the network will undoubtedly reduce the number of addresses. So i want to know that How to calculate Subnet mask Please suggest. Thanks in advance.

[Milton.J]

Subnet addressing technology, also known as subnet routing is the most widely used IP network address reuse approach has now been standardized and become part of the IP address mode. 32-bit IP address is divided into two parts, namely, the network number and host number, respectively, they called the IP address of the "network between the network part" and "local section." Subnet addressing technology will be "local part" are further divided into "physical network" section and the "host" of two parts, in which "physical network" part of the same IP network address used to identify under the different physical networks, often called the "mask bit "," Subnet Mask number ", or" subnet mask ID ", is based on the different subnet mask ID to identify the network. Check and reply.

[Spyrus]

Subnet by IP protocol standards require the use of a subnet for each network have chosen a 32 bit mode, if the bit pattern in a position 1, then the corresponding IP address of a certain network address (including network components and sub - subnet mask number) in the 1; if the bit pattern in a position 0, then the corresponding IP address for the host address of someone in one. For example, the binary bit pattern: 11111111 11111111 11111111 00000000, the first three bytes of the whole one, on behalf of the corresponding IP address of the highest in three bytes for the network address; 0 after a byte-wide, on behalf of the corresponding IP address of the last of a word section for the host address. For ease of use, and often use "dotted integer notation" to indicate an IP address and subnet mask, for example, Class B address subnet mask (11111111 11111111 1111111100000000) is: 255.255.25.0. All the best.

[Snake08]

The network number and host number can be obtained following method:
(1) It will convert the IP address of 192.9.200.13 binary 1,100,000,000,001,001 1,100,100,000,001,101
(2) The subnet mask of 255.255.255.0 is converted to a binary 11111111 11111111 1,111,111,100,000,000
(3) The number of the above two binary logic and (AND) operation, the result shall be part of the network. "1,100,000,000,001,001 1,100,100,000,001,101" and "11111111 11111111 11111111 00000000" to "and" algorithms to be "1,100,000,000,001,001 1,100,100,000,000,000," that is "192.9.200.0", which is the IP address of the network number, or called "network address."
(4) The binary subnet mask value is negated, another with the IP address and (AND) operation, the results obtained shall be the host part of the. If the "00000000 00000000 00000000 11111111 (subnet mask values) anti-" and "1,100,000,000,001,001 1,100,100,000,001,101" to and after the operation to be "00000000 00000000 0,000,000,000,001,101," that is "0.0.0.13", which is the IP address of the host number (can be simplified to "13").

[Zachary]

You need to divide into two sub-networks the number of m-th power. To sub-eight sub-network, 8 = 23. If it is not good or two the number of Discovery-th power, then it greatly principles, such as to be divided into six, the same to be considered 23. It will be the previous step to determine the power m occupied by high-order m-bit host address, after the conversion to decimal. If m is 3, said the host bits there are three are classified as "network ID" occupier, as the network ID should be full of "1", so the corresponding number of bytes the host segment for "11.1 million." After converted to decimal 224, which ultimately determine the subnet mask. If it is class C network, the subnet mask of 255.255.255.224; if it is class B network, the subnet mask of 255.255.224.0; if it is class A network, the subnet mask of 255.224.0.0. Allt he best.

[Big Fish]

The fast computer subnet mask method are used to calculate the number of sub-networks- In order to find out the subnet mask must first be classified before the subnet number, and each sub-net the number of hosts required. Then calculated according to the following basic steps: the number of sub-network into a binary to represent; To obtain the number of binary digits subnet (n); obtain the IP address class, subnet mask, and then the host address part of the first n positions "1", that is, arrive at the IP address into subnet mask. Check and reply.