Lecture 5: Designing IP Addressing in the Network II

Planning for Information Network

Lecture 5: Designing IP Addressing in the
Network II

Contents:
Subnetting the Subnet
Interconnecting Private and Public Addresses

Subnetting the Subnet:

When contiguous 1s are added to the default mask, making the all-1s field in the mask longer, the definition of the network part of an IP address is extended to include subnets.

Adding bits to the network part of an address decreases the number of bits in the host part.

***The number of subnetworks created is calculated by the formula 2s, where s is the number of bits by which the default mask was extended.

Interconnecting Private and Public Addresses:

* According to an organization needs, it can use both public and private addresses.

* A router or firewall acts as the interface between the network’s private and public sections.

* When private addresses are used for addressing in a network and this network must be connected to the Internet, Network Address Translation (NAT) or Port Address Translation (PAT) must be used to translate from private to public addresses and vice versa.

* NAT or PAT is required if accessibility to the public Internet or public visibility is required.