IP Addressing
Private Network IP Addresses
RFC 1918 defines blocks of addresses for use on private networks:
•10.0.0.0 – 10.255.255.255
•172.16.0.0 – 172.31.255.255
•192.168.0.0 – 192.168.255.255
Network Address Translation (NAT)
Private networks can only connect to the public Internet by using a Network Address Translation (NAT) device (a router, for example) or a proxy server which has been assigned a public IP address. These network devices use a public IP address to request information from the Internet on behalf of the private IP addressed devices on the associated private network.
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192.168.0.2 | Ethernet |
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Host 2 |
192.168.0.3 |
192.168.0.1 | Public IP |
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NAT Router
Internet
Figure A-5 NAT Router Example
This use of private addresses helps to conserve public IP addresses.
Subnets
Subnets can be defined as the further segmentation of the InterNIC assigned Network ID IP address. The amount and type of subnetting performed by the organization is determined by the network layout.
In the process of subnetting, bits are borrowed from the host ID portion of an IP address and are then given to the network ID. Then a “Subnet Mask” gets assigned to the host along with the IP address.
Vipersat |
