Hughes DIRECWAY DW4020 User Manual

10.0.0.0        -   10.255.255.255 (10/8 prefix)
172.16.0.0      -   172.31.255.255 (172.16/12 prefix)
192.168.0.0     -   192.168.255.255 (192.168/16 prefix)

The first block is the "24-bit block," the second is the "20-bit 
block," and to the third is "16-bit" block. Note that the first block 
is nothing but a single class A network number, while the second 
block is a set of 16 contiguous class B network numbers, and 
third block is a set of 256 contiguous class C network numbers.

An enterprise that decides to use IP addresses out of these address 
spaces can do so without any coordination with IANA or an 
Internet registry. The address space can thus be used by many 
enterprises. Addresses within this private address space will only 
be unique within the enterprise, or the set of enterprises which 
choose to cooperate over this space so they may communicate 
with each other in their own private internet. An enterprise that 
requests IP addresses for its external connectivity will never be 
assigned addresses from the blocks defined above.

DW4020 customers who use private addressing must install a 
router or switch between the DW4020 and their network. They 
will also need to provide the installer with the LAN Gateway 
address and, if applicable, the LAN subnet mask (see Configuring 
the Gateway host in Chapter 3).