How to solve the problem of insufficient IP address space?

IP address space is insufficient, IP address space is limited, about 4.3 billion; with the development of the network, there are more and more networking devices; there is a problem of waste in the use of IPv4 addresses; IP addresses in the same network segment, if not used up, can not be used by hosts in other network segments; there are the following solutions: 1. Common address / private address 2. Subnetting 3.IPv6 one. Public address / private address-Common address: used on Internet, requires application and money;-Private address: used within a unit, organization or organization, does not need to apply or spend money to buy, and can be reused. Private address division: a 10.0.0.0-10.255.255.255 [/ 8] B 172.16.0.0-172.31.255.255 [/ 16] C 192.168.0.0-192.168.255.255 [/ 24] D 239.0.0.0-239.255.255.255 II. Subnetting: 1. Objective to reduce the waste of IP addresses in each network segment; 2. Definition: the host bit in the original IP address is changed into the network bit in the new IP address, so that the network bit becomes longer and the host bit becomes shorter. For example: given a network segment: 192.168.1.0 IP 24 there are now three new departments, different network segments in each department, 40 hosts in each department to minimize the waste of IP addresses in each department, please write down each different IP address space, as well as network address and broadcast address. Ideas: 1. First, pay attention to the number of host bits; n 2 to the power of n minus 2, which is about 40; therefore, n is greater than or equal to 6; 2. Secondly, focus on the network bits: masking 32murn, that is, 26 So the subnet mask bit 255.255.255.1923, The final new network segment is as follows: 192.168.1.0 / 26 192.168.1.0000 0000 / 26-192.168.1.0 / 26 192.168.1.0100 0000 / 26-192.168.1.64 / 26 192.168.1.1000 0000 / 26-192.168.1.128 / 26 192.168.1.1100 0000 / 26-192.168.1.192 / 26