Routing and Switching
Cisco
Cisco has got very many certifications and networking (CCNA) is just one of them.
Cisco Certified Network Associate (CCNA) is a certification program for entry-level network professionals, which helps maximize their investment in foundational networking knowledge and increase the value of system infrastructure network.
CCNA certification is for Network Specialists, Network Administrators, and Network Support Engineers with 1–3 years of experience and it validates our ability to install, configure, operate, and troubleshoot medium-size routed and switched networks.
Pursuing this certification helps one improve their skill sets and provide you with ability to manage and optimize network systems.
CCNA Routing and Switching focuses on network infrastructure, mainly routing and switching, but it also includes wireless access, security, and connectivity to branch offices using WAN
Networks
Networking is the connection of two or more computer nodes for the purpose of resource sharing, exchange files or electronic communications.
There several types of networks:
• Local Area Network
• Wide Area Network
• Wireless Local Area Network
• Metropolitan Area Network
Network Topologies
Network topology defines the structure of the network.
One part of the topology definition is the physical topology, which is the actual layout of the wire or media.
The other part is the logical topology which defines how the media is accessed by the hosts for sending data.
The following are the different arrangements in which we can organize computer nodes or rather types of topologies;
• Bus
• Ring
• Star
• Extended star
• Mesh topology
The OSI model
OSI (Open Systems Interconnection) is a reference model for how applications communicate over a network.
A reference model is a conceptual framework for understanding relationships. The purpose of the OSI reference model is to guide vendors and developers so the digital communication products and software programs they create can inter operate, and to facilitate a clear framework that describes the functions of a networking or telecommunication system
The main concept of OSI is that the process of communication between two endpoints in a network can be divided into seven distinct groups of related functions, or layers. Each communicating user or program is on a device that can provide those seven layers of function.
In this architecture, each layer serves the layer above it and, in turn, is served by the layer below it. So, in a given message between users, there will be a flow of data down through the layers in the source computer, across the network, and then up through the layers in the receiving computer.
