isibnet

Introduction This document describes basic information needed to configure your router such as how addresses are broken down and how subnetting works Prerequisites Requirements Cisco recommends that you have a basic understanding of binary and decimal numbers Components Used

- IPv4 Addressing and Subnetting - Hardware Addressing A hardware address is used to uniquely identify a host within a local network Hardware addressing is a function of the Data-Link layer of the OSI model (Layer-2) Ethernet utilizes the 48-bit MAC address as its hardware address

Introduction The process of subnetting is both a mathematical process and a network design process Mathematics drives how subnets are calculated identified and assigned The network design and requirements of the organization drive how many subnets are needed and how many hosts an individual subnet needs to support

Subnetting can improve network performance by splitting up collision and broadcast domains Subnets can reflect organizational structure and help support security policies WAN links typically join different subnets Subnets can define administrative units and hence support the structuring and delegation of administrative tasks

Video Demonstration – Subnetting with the Magic Number Magic number technique used to calculate subnets Magic number is simply the place value of the last one in the subnet mask /25 11111111 11111111 11111111 10000000 magic number = 128 /26 11111111 11111111 11111111 11000000 magic number = 64