Hola Amigo !
And here we are again to provide you with all the stuffs required for gaining theoretical and practical knowledge about networking. This is going to be more like a series of post to cover all the topics necessary for you to clear the Cisco based certification in networking – CCNA.
Introduction – Topics Overview
- What is Computer Networks ?
- Why Networking ?
- Computer Network Elements
- Network Typologies
- Modes of Communication
- Medium of Communication
- CSMA/CD Protocol
What is a Network !
A Computer network consist of devices which are connected to each other either by wired or wireless medium for the purpose of sharing resources between the devices. A network can be as simple as two computer connected to each other through the LAN cable and as huge as the INTERNET you are using to read this article online.
Why Networking ?
The devices are networked together for any of the following reasons,
- For the purpose of resource and data sharing.
- Distributing the work to reduce the complexity
- To access World Wide Web
- To access data and devices remotely
- Other reasons
Computer Network Elements
—> End Devices :
Any standalone device,It may be a PC, a Laptop,a Printer, or a Server that has resource for sharing with other devices and has the processing capability to process the data and produce an output comes under this category. In networking they are generally called us as Node. Major companies manufacturing these devices are Apple, Samsung, HP, Dell, Lenovo, etc..
—> Networking Devices :
Devices like a hub, a switch or a router used in a network to connect between two or many end devices comes under this category. Major companies manufacturing these Networking Devices are Cisco, D-Link, Nokia Networks, etc..
—> Bus Network Topology :
Bus topology otherwise called as Line topology has a bus(copper cable/optic fiber cable) as a backbone which is used for connecting end devices and networking devices in a linear fashion. Mostly this topology is used for smaller network. Terminators will be connected on both the ends of the bus to terminate the connection after that point and if some extra device is added to the network it will reduce the average speed of communication between the network. Troubleshooting is a big problem in this topology as it is hectic to identify that single node which faces the issue. This has both advantages and disadvantages and it varies with the scenario.
—> Ring Network Topology :
In this circular topology the end devices are connected to two other neighbouring devices side by side like a point in the circle. This topology is rarely used now ad days. The traveling of data in this topology can be either in one direction (Clockwise/anticlockwise) or Bi-directional.The whole network fails if a single point of the circle breaks and it is the major disadvantage of this network. adding an extra node will not affect the performance of the network. The lag in speed occurs since data must go through in between nodes from source to the destination.
—> Star Topology :
Here all nodes are connected to a central point. the central point may be a hub or switch which has the capability to route and manage the whole underlying network. The primary benefit of using the star topology is that even if a node goes down it wont have any kinda effect on the network. Commonly Bus topology and star topology are used together and it is called as tree topology.
—> Mesh Topology :
The greatest of all ! Mesh topology. Here each node is connected to each other node in the network. Thus if “n” no of nodes are present each node is connect with other nodes using (n-1) links.Here single point of failure is impossible. Efficient routing of data happens as nodes are connected directly, dynamically and non-hierarchical.
Modes of Communication
—> Simplex :
Its simple ! It involves two devices of which one acts as the receiver and the other one is the sender.
—> Half Duplex :
At certain time the device can either send or receive data. The data from point 1 travels to point 2 and it can also happen the other way but not at the same time.
—> Full Duplex :
Every device can send and receive data at the same time.
Medium of Communication\
This protocol prevents collision between data sent from different devices in Half-duplex mode of communication by sensing whether any electrical signal is present at the channel or not and if nothing is present it starts sending data from source to destination.