A computer network connects two or more devices together to share information and services, including:
•Documents
•Websites
•Databases
•Music
•Printers and faxes
•Telephony and videoconferencing
•Email and messaging
•Documents
•Websites
•Databases
•Music
•Printers and faxes
•Telephony and videoconferencing
•Email and messaging
Protocols are rules that govern how devices communicate and share information across a network. Examples of protocols include:
• IP – Internet Protocol
• HTTP - Hyper Text Transfer Protocol
• SMTP – Simple Mail Transfer Protocol
Multiple protocols often work together to facilitate end-to-end network communication, forming protocol suites or stacks.
• IP – Internet Protocol
• HTTP - Hyper Text Transfer Protocol
• SMTP – Simple Mail Transfer Protocol
Multiple protocols often work together to facilitate end-to-end network communication, forming protocol suites or stacks.
Network reference models were developed to allow products from different
manufacturers to interoperate on a network.
The Open Systems Interconnect (OSI) and Department of Defense (DoD)
models are the most widely recognized reference models.
manufacturers to interoperate on a network.
The Open Systems Interconnect (OSI) and Department of Defense (DoD)
models are the most widely recognized reference models.
Network types by size:
A LAN is generally a high-speed network that covers a small geographic
area, usually contained within a single building or campus. A LAN is
usually under the administrative control of a single organization. Ethernet is
the most common LAN technology.
A WAN can be defined one of two ways. The book definition of a WAN is a
network that spans large geographical locations, usually to connect multiple
LANs. This is a general definition, and not always accurate.
A more practical definition of a WAN is a network that traverses a public or
commercial carrier, using one of several WAN technologies. A WAN is often
under the administrative control of several organizations (or providers), and
does not necessarily need to span large geographical distances.
A MAN (Metropolitan Area Network) is another category of network,
though the term is not prevalently used. A MAN is defined as a network that
connects LAN’s across a city-wide geographic area.
An internetwork is a general term describing multiple networks connected
together. The Internet is the largest and most well-known internetwork.
A LAN is generally a high-speed network that covers a small geographic
area, usually contained within a single building or campus. A LAN is
usually under the administrative control of a single organization. Ethernet is
the most common LAN technology.
A WAN can be defined one of two ways. The book definition of a WAN is a
network that spans large geographical locations, usually to connect multiple
LANs. This is a general definition, and not always accurate.
A more practical definition of a WAN is a network that traverses a public or
commercial carrier, using one of several WAN technologies. A WAN is often
under the administrative control of several organizations (or providers), and
does not necessarily need to span large geographical distances.
A MAN (Metropolitan Area Network) is another category of network,
though the term is not prevalently used. A MAN is defined as a network that
connects LAN’s across a city-wide geographic area.
An internetwork is a general term describing multiple networks connected
together. The Internet is the largest and most well-known internetwork.
Some networks are categorized by their function, as opposed to their size.
A SAN (Storage Area Network) provides systems with high-speed, lossless access to high-capacity storage devices.
A VPN (Virtual Private Network) allows for information to be securely sent across a public or unsecure network, such as the Internet.
Common uses of a VPN are to connect branch offices or remote users to a main office.
A SAN (Storage Area Network) provides systems with high-speed, lossless access to high-capacity storage devices.
A VPN (Virtual Private Network) allows for information to be securely sent across a public or unsecure network, such as the Internet.
Common uses of a VPN are to connect branch offices or remote users to a main office.
Network Architectures:
A host refers to any device that is connected to a network.
A host can also
be defined as any device assigned a network address.
A host can serve one or more functions:
• A host can request data, often referred to as a client.
• A host can provide data, often referred to as a server.
• A host can both request and provide data, often referred to as a peer.
Because of these varying functions, multiple network architectures have
been developed, including:
• Peer-to-Peer
• Client/Server
• Mainframe/Terminal
A host refers to any device that is connected to a network.
A host can also
be defined as any device assigned a network address.
A host can serve one or more functions:
• A host can request data, often referred to as a client.
• A host can provide data, often referred to as a server.
• A host can both request and provide data, often referred to as a peer.
Because of these varying functions, multiple network architectures have
been developed, including:
• Peer-to-Peer
• Client/Server
• Mainframe/Terminal
Peer-to-Peer Architecture:
all hosts on the network can both request and provide data and services.
For example, two Windows XP workstations configured to share files would be considered a peer-to-peer network.
Peer-to-peer networks are very simple to configure, yet this architecture presents several challenges.
Data is difficult to manage and back-up, as it is spread across multiple devices.
Security is equally problematic, as user accounts and permissions must be configured individually on each host.
all hosts on the network can both request and provide data and services.
For example, two Windows XP workstations configured to share files would be considered a peer-to-peer network.
Peer-to-peer networks are very simple to configure, yet this architecture presents several challenges.
Data is difficult to manage and back-up, as it is spread across multiple devices.
Security is equally problematic, as user accounts and permissions must be configured individually on each host.
Client/Server Architecture:
Clients request data and services stored on servers. An example of a client/server network would be Windows 10 workstations accessing files off of a Windows 2016 server.
There are several advantages to the client/server architecture.
Data and services are now centrally located on one or more servers, consolidating the management and security of that data. As a result, client/server networks can scale far larger than peer-to-peer networks.
One key disadvantage of the client/server architecture is that the server can present a single point of failure. This can be mitigated by adding redundancy at the server layer.
Clients request data and services stored on servers. An example of a client/server network would be Windows 10 workstations accessing files off of a Windows 2016 server.
There are several advantages to the client/server architecture.
Data and services are now centrally located on one or more servers, consolidating the management and security of that data. As a result, client/server networks can scale far larger than peer-to-peer networks.
One key disadvantage of the client/server architecture is that the server can present a single point of failure. This can be mitigated by adding redundancy at the server layer.
Mainframe/Terminal Architecture:
A single device (the mainframe) stores all data and services for the network.
This provides the same advantages as a client/server architecture – centralized management and security of data.
Additionally, the mainframe performs all processing functions for the dumb terminals that connect to the mainframe.
The dumb terminals perform no processing whatsoever, but serve only as input and output devices into the mainframe.
A dumb terminal typically consists of only a keyboard/mouse, a display, and an interface card into the network.
A single device (the mainframe) stores all data and services for the network.
This provides the same advantages as a client/server architecture – centralized management and security of data.
Additionally, the mainframe performs all processing functions for the dumb terminals that connect to the mainframe.
The dumb terminals perform no processing whatsoever, but serve only as input and output devices into the mainframe.
A dumb terminal typically consists of only a keyboard/mouse, a display, and an interface card into the network.
Network Reference Models:
Internetworking present challenges - interoperating between products from different manufacturers requires consistent standards.
Network reference models were developed to address these challenges.
A network reference model serves as a blueprint, detailing how communication between network devices should occur.
The two most recognized network reference models are:
1.The Open Systems Interconnection (OSI) model
2.The Department of Defense (DoD) model
Internetworking present challenges - interoperating between products from different manufacturers requires consistent standards.
Network reference models were developed to address these challenges.
A network reference model serves as a blueprint, detailing how communication between network devices should occur.
The two most recognized network reference models are:
1.The Open Systems Interconnection (OSI) model
2.The Department of Defense (DoD) model
OSI Reference Model:
The Open Systems Interconnection (OSI) model was developed by the International Organization for Standardization (ISO), and formalized in 1984.
It provided the first framework governing how information should be sent across a network.
The OSI model consists of seven layers, each corresponding to a specific
network function:
7. Application
6. Presentation
5. Session
4. Transport
3. Network
2. Data-link
1. Physical
The Open Systems Interconnection (OSI) model was developed by the International Organization for Standardization (ISO), and formalized in 1984.
It provided the first framework governing how information should be sent across a network.
The OSI model consists of seven layers, each corresponding to a specific
network function:
7. Application
6. Presentation
5. Session
4. Transport
3. Network
2. Data-link
1. Physical