Term Definitions
Cisco defines these terms as follows:
Inside local address - The
IP address assigned to a host on the inside network. This is the address configured as a parameter of the computer's
OS or received via dynamic address allocation protocols such as DHCP. The address is likely not a legitimate
IP address assigned by the Network Information Center (NIC) or service provider.
Inside global address - A legitimate
IP address assigned by the NIC or service provider that represents one or more inside local
IP addresses to the outside world.
Outside local address - The
IP address of an outside host as it appears to the inside network. Not necessarily a legitimate address, it is allocated from an address space routable on the inside.
Outside global address - The
IP address assigned to a host on the outside network by the host's owner. The address is allocated from a globally routable address or network space.
The above definitions still leave a lot to be interpreted. For this example, this document redefines these terms by first defining "local address" and "global address." Keep in mind that the terms "inside" and "outside" are NAT definitions. Interfaces on a NAT router are defined as "inside" or "outside" with the NAT configuration commands,
ip nat inside and
ip nat outside. Networks to which these interfaces connect can then be thought of as "inside" networks or "outside" networks, respectively.
Local address - A local address is any address that appears on the "inside" portion of the network.
Global address - A global address is any address that appears on the "outside" portion of the network