The most of the organization uses computer network and it increases data due to the development of internet and computerizations which enable for file download, browsing internet and also make their work easier by sharing their files and folders. When no. of systems increases in computer network and it generates the heavy traffic and creates collision thus reduces network performance as well as the security. The overhead information increases due to broadcasting concepts and The traffic over the network address space utilization cannot be controlled by installing more routers or by increasing the size of the routing tables. Every system has given a unique IP address consisting of 32 bits specified in dotted decimal notation. To overcome from these issues we are using subnetting. The basic purpose of subnetting is to control the traffic over the networks and dividing one network into many smaller networks. An IP address consists of network number and host number therefore subnetting is dividing the network number part classes into pieces. In subnetting bits are borrowed from host ID part to the network ID part. It has network number, subnet number and host number. In this project subnetting improve the network performance and security and other parameters in the network for excellent communication.