Fast subnet division method

Fast subnet division method subnet division basics: subnetting advantages: 1. reduce network traffic 2. improve Network Performance 3. simplified Management 4. how to Create a subnet that is easy to expand the geographical scope: how to divide subnets? First, you must note that the power of 2: The power of 2 0 to the power of 9 are: 1, 2, 4, 8, 16, 32, 64,128,256, and 512, respectively. It is also worth noting that the subnet division uses the host bit to take the removed part as the subnet bit. Therefore, this means that the more subnets you divide, the fewer hosts you will have. Subnet Mask (Subnet Masks): www.2cto.com Subnet mask is used to identify which part of the IP address is the network address, which part is the host address, consisting of 1 and 0, long 32-bit, the value 1 indicates the network number. not all networks require subnets. Therefore, we introduce the default subnet mask (default subnet mask ). the default subnet mask of Class a ip addresses is 255.0.0.0; Type B is 255.255.0.0; Type C is 255.255.255.0. Classless Inter-Domain Routing (CIDR): CIDR is called Classless Inter-Domain Routing. ISPs usually use this method to allocate addresses to customers. ISP provides customers with 1 block size ), similar to this: 192.168.10.32/28. The number in this row tells you what the subnet mask is, And/28 indicates how many bits are 1 and the maximum is/32. however, you must know that, whether it is A class A, B class, or other class addresses, the maximum available value is/30, that is, 2 bits are reserved for the host space. CIDR value: 1. mask 255.0.0.0:/8 (default mask for Class A addresses) 2. mask 255.255.0.0:/16 (default mask for Class B addresses) 3. mask 255.255.255.0:/24 (default mask for Class C addresses)
Dividing class A, Class B, Class C address subnets: Several shortcuts to dividing subnets: 1. How many subnets will your selected subnet mask generate?: X to the power of 2-2 (x represents the subnet bit, that is, the part in hexadecimal notation 1) PS: Here x refers to the subnet bit after removing the default mask, for example, the network address 192.168.1.1 and mask 255.255.255.255.192. Because it is a class C address, the mask is 255.255.255.255.0. Then zookeeper 192 (x. x. x.11000000) uses two 1 as the subnet bit. Www.2cto.com 2. How many hosts can each subnet have?: The power of y of 2-2 (y represents the host bit, that is, the part of the hexadecimal 0) 3. What is the valid subnet?: Valid subnet number = 256-10 Subnet Mask (the result is block size or base number) 4. What is the broadcast address of each subnet?: Broadcast address = subnetwork number-15. What are the valid hosts of each subnet?: The valid host address is ignored. finally, valid 1 Host address = next subnet number-2 (that is, broadcast address-1) according to the above shortcut to divide the specific instance of the subnet: Class C address Example 1: network address 192.168.10.0; subnet Mask 255.255.255.192 (/26) 1. number of subnets = 2*2-2 = 22. number of hosts = 6 to the power of 2-2 = 623. valid subnet?: Block size = 256-192 = 64; therefore, the first subnet is 192.168.10.64, and the second subnet is 192.168.10.1284. broadcast address: The next subnet-1. the broadcast addresses of the two subnets are 192.168.10.127 and 192.168.10.1915. valid host range: the host address of the first subnet is 192.168.10.65 to 192.168.10.126; the second is 192.168.10.129 to 192.168.10.190 www.2cto.com Class C address Example 2: network address 192.168.10.0; subnet mask 255.255.255.255.128 (/26) I know that the example I mentioned only has one subnet bit. This is generally invalid (as specified in the RFC document ). But! There is no such thing as absolute, isn't it? This subnet mask can help you when you need 126 hosts in each subnet of two subnets, but this is implemented in special cases. In global configuration mode of a CISCO router, enter the ip subnet-zero command to tell your router to break the rule and use a one-bit subnet Mask (this command is usually running cisco ios 12. x exists on all routers by default) 1. number of subnets = 22. number of hosts = Power 7 of 2-2 = 1263. valid subnet?: Block size = 256-128 = 128; therefore, the first subnet is 192.168.10.0, and the second subnet is 192.168.10.1284. broadcast address: The next subnet-1. the broadcast addresses of the two subnets are 192.168.10.127 and 192.168.10.2555. valid host range: the host address of the first subnet is 192.168.10.1 to 192.168.10.126; the second is 192.168.10.129 to 192.168.10.254 Class B address Example 1: Network Address: 172.16.0.0; subnet mask 255.255.255.255.128 (/25) note! This is not the subnet mask of the class C address, but it is difficult to divide the subnet,! This mask is very useful because it creates 510 subnets, each subnet has 126 hosts, a good combination. 1. Number of subnets = 9 to the power of 2-2 = 5102. number of hosts = 7 to the power of 2-2 = 1263. valid subnet?: Block size = 256-255 =, 3 ,...... this is the value of the third eight-bit tuples, but you must not forget that there is another subnet bit in the fourth eight-bit tuples. Therefore, the fourth octal tuples are divided into two subnets. For example, if the third eight-bit tuples represent subnet 3, then the two subnets of the fourth eight-bit tuples are 172.16.3.0 and 172.16.3.1284. broadcast address: The next subnet-1. therefore, the broadcast addresses of the first subnet and the last subnet are 172.16.0.255 and www.2cto.com 172.16.1121275, respectively. valid host range: the host address of the first subnet is 172.16.0.129 to 172.16.0.254, and the last one is 172.16.255.0 to 172.16.0000126. (to add, someone may ask why the first subnet is not 172.16.0.0 --- 172.16.0.128? Don't forget! The subnet and host bit cannot be all 0 or all 1. 172.16.0.0 represents the entire 172.16.x.x network. Similarly, the last subnet cannot be 172.16.255.128 --- 172.16.255.255 .) Example 2: Network Address: 172.16.0.0; subnet mask 255.192.0 (/18) 1. number of subnets = 2*2-2 = 22. number of hosts = 14 to the power of 2-2 = 163823. valid subnet?: Block size = 256-192 = 64; therefore, the first subnetwork is 172.16.64.0, and the last one is 172.16.128.04. broadcast address: The next subnet-1. therefore, the broadcast addresses of the two subnets are 172.16.127.255 and 172.16.191.2555. valid host range: the host address of the first subnet is 172.16.64.1 to 172.16.127.254; the second is 172.16.128.1 to 172.16.191.254B. Example 3: Network Address: 172.16.0.0) 1. the number of subnets = 11 to the power of 2-2 = 2046 (because the default mask of Class B addresses is 255.255.0.0, so the network bit is 8 + 3 = 11) 2. number of hosts = 5 to the power of 2-2 = 303. valid subnet?: Block size = 256-224 = 32; therefore, the first subnetwork is 172.16.0.32, and the last one is 172.16.20.192 www.2cto.com 4. broadcast address: The next subnet-1. therefore, the broadcast addresses of the first subnet and the last subnet are 172.16.0.63 and 172.16.20.2235, respectively. valid host range: the host address of the first subnet is 172.16.0.33 to 172.16.0.62, and the last one is 172.16.0000193 to 172.16.0000223. The subnet division of Class A addresses is no different from that of class B and class C, the mask bit is changed from 16 bits and 8 bits to 24 bits. For example, the Network Address: 10.0.0.0; subnet mask 255.255.0.0 (/16) 1. the number of subnets = the power of 2-2 = 2542. number of hosts = 16 to the power of 2-2 = 655343. valid subnet?: Block size = 256-255 =, 3 ,......; therefore, the first subnet is 10.1.0.0 and the last subnet is 10.254.0.04. broadcast address: The next subnet-1. therefore, the broadcast addresses of the first subnet and the last subnet are 10.1.255.255 and 10.254.255.2555, respectively. valid host range: the host address of the first subnet is 10.1.0.1 to 10.1.255.254; the last one is 10.254.0.1 to 10.254.255.254