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02: A brief overview of Switch, Hub, Router, Bridge, Protocol, Network


Before delving into a deep explanation  of the chief topics in CCNA program, it is crucially significant to know at least some essential networking devices and terms to remove ambiguity. The following terms are of prime importance in the course: Switch, Router, Bridge, Hub, Protocol, Network.

A router is a networking device that connects two or more networks together, and forwards data packets between computer networks. Routers are considered as vital devices that are virtually indispensable. you will learn more about routers in the 'Routing' section. This is the sign given to routers on paper:
A switch is a networking device that connects two or more devices together on a computer network. Switches are usually found in most computer networks by virtue of their prominent roles they play in packet switching which you will learn in the section of 'Switching'. Switches are assigned the following sign:

A hub is also a networking device that connects networking devices together. It is similar to switch with some differences. Hubs is less advanced and secure than  switches. Certainly, those differences are explained in detail in the forthcoming lessons. This is the sign that is specified to hubs on paper: 

A bridge is networking device that connects two (LANs) local area networks (that uses the same protocol such as Ethernet or Token ring) togther. It is also expound in the next lessons. This device is given the following sign on paper: 

Note !! Networking devices can take on many different forms depending on the manufacturer, and the above devices' pictures are only the prevalent forms.


Protocol in networks can be defined as a set of predetermined rules that end points in computer networking or telecommunication connection use when they communicate. To make it plain, let's assume that two friends meet suddenly in the street and the following conversation takes place (human being protocol):

Hi Adam
                                                                    Hi James how are you ?
I'm crazy, I'm mad


As you notice, the conversation seems a little bit strange because one party responds with 'I'm cazy, I'm mad'  which makes the conversation unsuccessful. The reason behind the failure of the conversation is because the two parties do not follow a (or the same) protocol. When Adam says 'Hi James how are you', he is expecting James to say, for example, fine and you, or great and you, or perfect and you, or good and you, etc and if so happened, the conversation would succeed and they would be said to follow a protocol .

Let's consider the same example with some changes in conversation.

Hi Adam
                                                                    Hi James how are you ?
I'm fine and you
                                                                              good thanks

 As you see, here the conversation can be said to be successful because the two parties follow a (or the same) protocol. When James says 'I'm fine and you', he is already expecting Adam to say something like that (good thanks) which actually accured.  So, protocol is about respecting some predetermined rules by each party for a successful communication. The same thing applies to computer networks.  when one computer connects or exchanges information  with another remote computer, the two computer must follow a certain protocol to manage exchanging data or information. Each network protocol has a group of rules that each end point (computer, server...) must adhere to; otherwise, numerous errors will occur giving rise to stop or data transmission failure. This drawing shows a very simple example of protocol in computer networks.

                                                          Can I connect to you
                                  yes, you have my permission
                        <-----------------------------------------------                                               get the file  
                                                  Here is the file you requested

The above drawing (simplified example) is a protocol. both devices are following the same protocol, which leads to a successful communication.(note !! this is not a real scenario of data transmission; it is just a simplified example to show you how protocols work).
   The protocol used here is https.
                                               protocol       server name                 file  
To sum up, protocol is a group of predetermined rules that each device connected to the network must abide by in order to guarantee a successful communication.


 Network is a group of two or more devices connected together. Computer networks can take many different forms, and there are many different types of networks such as LAN, MAN, WAN, CAN, HAN, PAN. So, the word network means the connection of many devices togother or, in other words, many devices are linked together and each way of linking those devices has a special name in computer networks. All those ways are covered in this course (CCNA 200-120 R&S training course).

02: A brief overview of Switch, Hub, Router, Bridge, Protocol, Network Reviewed by BOUFTIRA on 8:33:00 PM Rating: 5

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