Hughes DIRECWAY DW4020 User Manual

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Appendix B • The Internet and the DW4020
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card.” The business owner can then assign his individual 
computer connections the numbers as shown in Figure 51.
A large organization like a university might apply for a class B 
network, in which the first two bytes are assigned and the last two 
bytes are available to the university to assign up to 64 thousand 
computers in sub-network LANs. For example, the university 
might be assigned a number like 170.15.*.*. The university, in 
turn, could make assignments such as: 170.15.100.* = Physics 
department LAN sub-network, 170.15.101.* = central library 
LAN1 sub-network, and so on. It is a common practice to assign 
the third byte to individual department LANs and the fourth byte 
to individual computers within each department.
A very large entity might require a class A network that would 
allow over 16 million individual IP address assignments. Table 11 
gives the ranges of IP addresses IANA reserves for specific 
purposes. 
HNS customers have already acquired IP address ranges and 
supply these as needed to HNS installers.
Note, however, that many organizations of various sizes now use 
private IP addressing (see Private IP addresses below)These 
organizations do not need to assign a unique public IP address to 
each computer (or "host") on their networks. 
Figure 51: IP addresses assigned to individual computer connections
Internet
address
192.77.43.2
192.77.43.3
192.77.43.4
192.77.43.5
Table 11: IP Address ranges
Category
Lowest address
Highest address
Example or comment
Class A network
0.1.0.0
126.0.0.0
9.*.*.* for IBM Corp.
Class B network
128.0.0.0
191.255.0.0
170.15.*.* – a university
Class C network
192.0.1.0
223.255.0.0
192.77.43.* – small business
D – multicast
224.0.0.0
239.255.255.255