public and private IP addresses

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introduction

The LIC uses IP addresses from three networks: the Internet, the LIC and the enterprise. Each network contains a big range of IP addresses.

Some IP addresses are public and the others are private. Public addresses can be used on the Internet. Private addresses are hidden from the Internet.

what it is

LIC topology: public and private network IP addresses
Internet facing public IP addresses (200.0.0.x)
LIC private IP addresses (192.168.x.x)
enterprise facing private IP addresses (10.2.x.x)

The IP addresses used by the LIC come from three big ranges of IP addresses. All the IP addresses in a network start with the same numbers.

The network has its own special IP address: the first one in the range is reserved as the network IP address. No host can use it.

  • The public network is for Internet use. The network address is 200.0.0.0. All the IP addresses start with "200.0.0.".
  • One private network is used inside the LIC. The network address is 192.168.0.0. All these IP addresses start with "192.168.".
  • The other private network is for enterprise use. The network address is 10.2.0.0. All these IP addresses start with "10.2.".

The NAT subnet 200.0.0.x contains the real live Internet addresses. These addresses actually belong to someone else. I can't really use these on the Internet.

LIC table: public network IP address, for Internet traffic
Description Address Netmask Prefix
LIC Internet NATs 200.0.0.0 255.255.255.0 /24

Within the LIC there is only one network, the 192.168.0.0/16 network. This is a different network to the enterprise and the Internet networks. It is the private network called 192.168.0.0/16 (gotta love these network names), or simply 192.168.0.0 to its friends. This is an Internet standard, described in RFC 1918. Addresses in private networks don't work on the Internet: network computers on the Internet refuse to deal with private addresses.

LIC table: private network IP address, for LIC internal traffic
Description Address Netmask Prefix
LIC network 192.168.0.0 255.255.0.0 /16

The enterprise uses a different private network.

LIC table: private network IP address, for enterprise traffic
Description Address Netmask Prefix
enterprise network 10.2.0.0 255.255.0.0 /16