LAN, WAN and Internet (1.3)
Most people never consider how the Internet works. In this section, you will begin to explore the elements that combine to enable network communications.
Components of a network (1.3.1)
In this section, you will begin to learn about devices and equipment that work together in networks.
Components of the network (1.3.1.1)
The path a message takes from the source to the destination can be as simple as a simple cable connecting one computer to another or as complex as a network literally covering the entire world. This network infrastructure is the platform that supports the network. It provides the stable and reliable channel on which our communications can take place.
The network infrastructure contains three categories of network components:
End devices
Intermediate devices
Network Media
Peripherals and media are the physical or hardware components of the network. Hardware includes network platform components that are typically visible, such as a laptop, computer, switch, router, wireless access point, or cabling used to connect devices. Sometimes, some network components may not be visible. In the case of wireless media, for example, messages are transmitted in the air using invisible radio or infrared waves.
Network components are used to provide services and processes. These services and processes are the communication programs, called software, run on networked devices. A network service provides information in response to a request. The services include many common network applications used daily by users, such as email hosting services and web hosting services. Processes provide the functionality that directs and moves messages across the network. The processes are less obvious to us, but they are essential to the functioning of networks.
Final devices (1.3.1.2)
The network devices that people know best are called end devices or hosts. These devices constitute the interface between the users and the underlying communication network.
Some examples of terminals are
Computers (workstations, laptops, file servers, web servers)
Network Printers
VoIP Phones
Telepresence terminals
Security cameras
Mobile handheld devices (such as smartphones, tablets, personal assistants, debit / credit card readers, and wireless barcode scanners)
A host device is either the source or the destination of a message transmitted over the network. In order to distinguish one host from another, each host in a network is identified by an address. When a host initiates a call, it uses the address of the destination host to specify where the message should be sent.
In modern networks, a host can act as a client, server, or both. The software installed on the host determines the role it plays on the network. Servers are hosts on which installed software enables them to provide information and services, such as e-mail or web pages, to other hosts on the network. Clients are hosts with installed software that allows them to request and view information obtained from the server.
Intermediate devices (1.3.1.3)
Intermediate devices interconnect the end devices. These devices provide connectivity and work behind the scenes to ensure that data travels over the network. Intermediate devices connect individual hosts to the network and can connect multiple individual networks to form an internetwork.
Activity 1.3.1.3: Inter-networks
Access the online course and watch the animation.
Examples of intermediate network devices are
Network Access Devices (Switches and Wireless Access Points)
Network interconnection devices (routers)
Security features (firewall)
The management of data passing through the network is also a role of the intermediate devices. These devices use the destination host address, along with network interconnect information, to determine the path that messages must take on the network.
Processes running on the intermediate network devices perform the following functions:
Regenerate and retransmit data signals
Retain information about existing paths on the network and internetwork
Notify other devices of errors and communication problems
Direct data on alternate paths in case of link failure
Classify and direct messages based on QoS priorities
Allow or deny the data flow, depending on the security settings
Network Media (1.3.1.4)
The communication on a network is carried out on a support. The medium provides the channel on which the message passes from the source to the destination.
Modern networks primarily use the following three types of media to interconnect devices and provide the path through which data can be transmitted:
Wire in the cables
Glass or plastic fibers (fiber optic cable)
Wireless transmission
Most people never consider how the Internet works. In this section, you will begin to explore the elements that combine to enable network communications.
Components of a network (1.3.1)
In this section, you will begin to learn about devices and equipment that work together in networks.
Components of the network (1.3.1.1)
The path a message takes from the source to the destination can be as simple as a simple cable connecting one computer to another or as complex as a network literally covering the entire world. This network infrastructure is the platform that supports the network. It provides the stable and reliable channel on which our communications can take place.
The network infrastructure contains three categories of network components:
End devices
Intermediate devices
Network Media
Peripherals and media are the physical or hardware components of the network. Hardware includes network platform components that are typically visible, such as a laptop, computer, switch, router, wireless access point, or cabling used to connect devices. Sometimes, some network components may not be visible. In the case of wireless media, for example, messages are transmitted in the air using invisible radio or infrared waves.
Network components are used to provide services and processes. These services and processes are the communication programs, called software, run on networked devices. A network service provides information in response to a request. The services include many common network applications used daily by users, such as email hosting services and web hosting services. Processes provide the functionality that directs and moves messages across the network. The processes are less obvious to us, but they are essential to the functioning of networks.
Final devices (1.3.1.2)
The network devices that people know best are called end devices or hosts. These devices constitute the interface between the users and the underlying communication network.
Some examples of terminals are
Computers (workstations, laptops, file servers, web servers)
Network Printers
VoIP Phones
Telepresence terminals
Security cameras
Mobile handheld devices (such as smartphones, tablets, personal assistants, debit / credit card readers, and wireless barcode scanners)
A host device is either the source or the destination of a message transmitted over the network. In order to distinguish one host from another, each host in a network is identified by an address. When a host initiates a call, it uses the address of the destination host to specify where the message should be sent.
In modern networks, a host can act as a client, server, or both. The software installed on the host determines the role it plays on the network. Servers are hosts on which installed software enables them to provide information and services, such as e-mail or web pages, to other hosts on the network. Clients are hosts with installed software that allows them to request and view information obtained from the server.
Intermediate devices (1.3.1.3)
Intermediate devices interconnect the end devices. These devices provide connectivity and work behind the scenes to ensure that data travels over the network. Intermediate devices connect individual hosts to the network and can connect multiple individual networks to form an internetwork.
Activity 1.3.1.3: Inter-networks
Access the online course and watch the animation.
Examples of intermediate network devices are
Network Access Devices (Switches and Wireless Access Points)
Network interconnection devices (routers)
Security features (firewall)
The management of data passing through the network is also a role of the intermediate devices. These devices use the destination host address, along with network interconnect information, to determine the path that messages must take on the network.
Processes running on the intermediate network devices perform the following functions:
Regenerate and retransmit data signals
Retain information about existing paths on the network and internetwork
Notify other devices of errors and communication problems
Direct data on alternate paths in case of link failure
Classify and direct messages based on QoS priorities
Allow or deny the data flow, depending on the security settings
Network Media (1.3.1.4)
The communication on a network is carried out on a support. The medium provides the channel on which the message passes from the source to the destination.
Modern networks primarily use the following three types of media to interconnect devices and provide the path through which data can be transmitted:
Wire in the cables
Glass or plastic fibers (fiber optic cable)
Wireless transmission
