The method of S series switches divide subnet

By further dividing the IP part of the IP address into several subnets, it solves the problem that the IP address space is low and the two-level IP address is not flexible enough.
When a unit of the host a lot, in order to facilitate management, the unit can be inside the host number and then further divided into multiple subnets. Through the subnetting, the entire network address can be divided into more small networks.
Subnet division is the behavior of the network, from the outside, this unit has only one network number. Only when the external message into the scope of the unit, the unit of the routing equipment according to the subnet number and then routing, find the destination host.
In the case of a subnet with a Class B IP address, the subnet mask consists of a series of consecutive "1" and a string of consecutive "0". "1" corresponds to the network number and subnet number field, and "0" corresponds to the host number field.
Class B address of the Host-id high 5bits used to divide the subnet, Subnet-id range from 00000 ~ 11111, a total of 32 (2 5 times) subnet. Subnet corresponding to the subnet mask will be a corresponding change, such as Subnet-id 11111 subnet mask is The result of the execution and operation of the IP address and its corresponding mask bit is the network address.
To divide a subnet number field is to pay the price. For example, a Class B IP address can hold 65534 (2 16-party-2) host numbers. But the division of the 5bits long subnet field, up to 32 subnets, each subnet has 11bit host number, that is, each subnet can have up to 2046 (2 of 11 times - 2, remove all 1 and all 0 Host number) host number. So the total number of host numbers is (32 x 2046 = 65472), less than 62 when the subnet is not divided.

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