Planning - Lecture 5: Designing IP Addressing in the Network II

Planning for Information Network
Lecture 5:Designing IP Addressing in the
Network II

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.
Determining the Size of the Network
The first step in designing an IP addressing plan is determining the size of the network to establish how many IP subnets and how many IP addresses are needed on each subnet. To gather this information, we need to answer the following questions:
? How many locations does the network consist of ?: The designer must determine the number and type of locations.
? How many devices in each location need addresses?: The network designer must determine the number of devices that need to be addressed, including end systems, router interfaces, switches, and any other devices.
? What are the IP addressing requirements for individual locations?: The designer must collect information about which systems will use dynamic addressing, which will use static addresses, and which systems can use private instead of public addresses.