- if a subnet consists of 100 class C networks and if these addresses are randomly chose
- the routers external to the supernet requires 100 entries (one for each class C network) for the supernet
- it would be desirable if only 1 entry is required
- this can be achieved by carefully assigning addresses
- the number of blocks must be a power of 2(1,2,4,8,16...).
- the blocks must be contiguous in the address space (no gaps between the blocks).
- the third byte of the first address in the super block must be evenly divisible by the number of block. In other words, if the number of block is N, the third byte must be divisible by N.