Well, IPswen can do this trick in a relatively simple way, and easily "squeezes" the whole IPv4 address space into its shortest length "level 0" base address sp

Well, IPswen can do this trick in a relatively simple way, and easily "squeezes" the whole IPv4 address space into its shortest length "level 0" base address space. The secret is simple: yes, variable length encoding. You may refer to the above reply for details.