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    NETWORK DEVICES        DATA COMMUNICATION SYSTEM

     There are various devices used in a network. These include:   Data communication is the process of exchanging data between two devices.
       Network Interface Card (NIC): A device attached to a computer
     that enables communication over a network. The NIC contains a
     ROM chip  that  has a  unique  number  called  the  Media Access   Sender  Message                     Receiver
     Control (MAC) address, identifies the computer on the network.
                                                              Transmission Medium
                                  Rule 1, Rule 2, ... Rule n                              Rule 1, Rule 2, ... Rule n
       Modem: A device that allows computers and other devices to connect to   Protocol         Protocol
     the internet. It converts digital data into analog signals for transmission over
     telephone lines and vice versa.  There are five main components in a data communication system:
                         Message: This refers to data or a piece of information that is to be communicated.
         Hub: A device that joins multiple computers to form a single network     Sender: This is a source  in a data  communication  system.  It is a device  that  sends a
     segment. It forwards data to all connected computers.
                        data message.

                         Receiver: This is the destination of the final message sent by the source. It is a device that
        Switch: A device that connects multiple computers within a Local
     Area Network (LAN). It manages data traffic to ensure that data   receives messages.
     reaches  only  the  intended  destination.  Unlike  a  hub,  a  switch     Transmission medium: This is the channel or bridge through which the message travels from
     forwards data only to the target device.  the sender to the receiver.
                         Protocol: This refers to a set of rules or guidelines that defines how data is transmitted and
       Router: A device  that connects  different networks and directs  data   received over a network.
     packets between them based on their IP addresses.

        Network repeater: A device that boosts incoming electrical, wireless or optical   NETWORK PROTOCOLS
     signals. It amplifies signals to prevent them from becoming too weak or corrupted
     during transmission.  A network  protocol  is  a set  of rules that  are applicable  for a network  to  define  how data  is
                     transmitted and received between the devices connected to the network. Some commonly used

        Gateway: A device that connects dissimilar networks those using different   network protocols include:
     protocols. A gateway takes data from one system, interprets it and     Transmission  Control Protocol/Internet  Protocol  (TCP/IP): The protocol  that  is used  to
     transfers it to another system.  connect devices on the Internet. It sends data in the form of packets and reassembles them at
                        the destination.

        Bridge: A device that connects similar networks, usually LANs using     Hypertext Transfer Protocol (HTTP): The protocol that ensures smooth transfer of web pages
     the same hardware  and protocols.  It reduces  the traffic on other   between a server and browser.
     network segments as it filters the data based on the MAC addresses     Hypertext Transfer  Protocol  Secure (HTTPS): A secure  version of HTTP  that  encrypts  the
     of the source and destination before forwarding it.
                        communication between browser and server.

                         File Transfer Protocol (FTP): A standard network protocol that is used to transfer files from
     Imagine  computer  networks as highways in the sky. What kinds of vehicles would     one computer (host) to another.
     travel on these highways and what destinations would they reach?
                         Simple Mail Transfer Protocol (SMTP): An Internet standard used for sending emails.

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                                                                                                   Networks Around Us

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