Cisco Packet Tracer:

Cisco Packet Tracer is a cross platform simulation tool designed by Cisco Inc. which allows to create network topologies and helps in simulating network systems. The tool helps in simulating the configurations of Cisco routers and switches using a simulated command line or graphical user interface.  The graphical user interface allows for drag and drop functionality allowing for addition and removal of the devices. The tool is mainly focused towards CISCO devices for helping students to understand CCNA concepts. 

Packet tracer can run on various operating systems like Linux, Windows, Mac moreover mobile apps for android and iOS is also available. Packet Tracer supports lot of simulated Application Layer Protocol as well as basic routing protocols like RIP, OSPF, EIGRP, BDP.  Packet Tracer also supports multi-user system that enables multiple users to connect multiple topologies together over a computer network. 

Main role of packet tracer allows students to design complex and large networks, which might not be feasible with physical hardware due to costs. The application itself only has a small numbers of features found with in the actual hardware running a current version of Cisco Ios. Thus packet tracer is unsuitable for modelling production networks. Packet Tracer can be useful for understanding abstract networking concepts, such as the Enhanced Interior Gateway Routing Protocol by animating these elements in a visual form. Packet Tracer is also useful in education by providing additional components, including an authoring system, network protocol simulation and improving knowledge an assessment system.