Firstly, we will begin with communication models...
Open System Interconnection - OSI
Open System Interconnection or OSI is an ISO standard for worldwide communication that defines a networking framework, this implements protocols onto seven layers; Application, Presentation, Session, Transport, Network, Data Link and Physical. Control is passed between one layer to the next, starting at the Application layer and ending at the Physical layer.
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| Figure 1. OSI Model - Layers (Datacombasic.blogspot.co.uk, 2011) |
In this image (see Figure 1.), it shows the seven layers which make up the OSI model, it also shows the layer description and the data type. This diagram is quite detailed, informative and generally helps explain this model.
Functions of OSI Layers
In this next section I will be explaining the functions of the OSI model, going through each layer...
Layer 1 - Physical
Layer 1 - Physical transmits data in sequences of bits, which include; electrical impulse, light or radio signal. It also provides the hardware capability of sending and receiving data on a carrier; including set cables, cards and physical aspects. Fast Ethernet and ATM are protocols with Physical layer properties.
Layer 2 - Data Link
Layer 2 - Data Link covers the encoding and decoding processes of data packets. It then looks at transmission protocols and also management, while going back to Layer 1, in order to resolve errors, flow control and frame synchronisation. This layer is split up into two smaller layers; MAC, which stands for Media Access Control and LLC, which stands for Logical Link Control.
The job of the MAC layer is to control how a computer on the network accesses data and gains the permission to transmit it, while the job of the LLC layer is to control frame synchronisation, flow control and error checking.
Layer 2 - Data Link covers the encoding and decoding processes of data packets. It then looks at transmission protocols and also management, while going back to Layer 1, in order to resolve errors, flow control and frame synchronisation. This layer is split up into two smaller layers; MAC, which stands for Media Access Control and LLC, which stands for Logical Link Control.
The job of the MAC layer is to control how a computer on the network accesses data and gains the permission to transmit it, while the job of the LLC layer is to control frame synchronisation, flow control and error checking.
Layer 3 - Network
Layer 3 - Network provides the network with the technologies for switching and routing. It can create paths known as virtual circuits which are used for transmitting data between nodes. Other functions related to this layer are routing and forwarding, addressing, inter-networking, error-handling, congestion-control and packet sequencing.
Layer 3 - Network provides the network with the technologies for switching and routing. It can create paths known as virtual circuits which are used for transmitting data between nodes. Other functions related to this layer are routing and forwarding, addressing, inter-networking, error-handling, congestion-control and packet sequencing.
Examples of Network are AppleTalk and IP (Internet Protocol).
Layer 4 - Transport
Layer 4 - Transport provides clear transfer of data between systems and devices and also has the job of delivering error-free messages in order without any data loss.
Layer 4 - Transport provides clear transfer of data between systems and devices and also has the job of delivering error-free messages in order without any data loss.
The Functions of the Transport layer are:
- The layer will accept a message from the next layer (Session), while splitting the message into smaller units and then passing them onto the Network layer. The next step would be for the layer to reassemble the message.
- When there aren't any message buffers available, the data transmitting station will stop sending messages.
Layer 5 - Session
Layer 5 - Session allows session establishment between processes running on different stations. It provides applications on different machines to establish, use and end a connection, which is called a session. Session support performs the functions that allow these processes to communicate over the network, performing security, name recognition, logging and so on.
Layer 5 - Session allows session establishment between processes running on different stations. It provides applications on different machines to establish, use and end a connection, which is called a session. Session support performs the functions that allow these processes to communicate over the network, performing security, name recognition, logging and so on.
Layer 6 - Presentation
Layer 6 - Presentation sets the data to be presented to the application layer. It can be viewed as the translator for the network. This layer may translate data from a format used by the application layer into a common format at the sending station, then translate the common format to a format known to the application layer at the receiving station.
This layer provides the following functions:
- Character code translation
- Data conversion: bit order
- Data compression: reduces the number of bits that need to be transmitted over the network.
- Data encryption: encrypt data for security purposes, for example; ASCII, TIFF, GIF, JPEG, MPEG
Layer 7 - Application
Layer 7 - Application serves as the window for users and application processes to access network services. This layer contains a variety of commonly needed functions:
- Resource sharing and device redirection
- Remote file access
- Remote Printer access
- Inter-process communication
- Network management
- Directory services
- Electronic messaging; e-mail and SMS
- Network Virtual Terminals
Transmission Control Protocol/Internet Protocol or TCP/IP is a communication protocol that connects hosts to the Internet and it is used for transmitting data across a network. The TCP/IP model has four layers; Application, Transport, Internet and Network Interface.
In the image to the left (see Figure 2.), it shows the TCP/IP model with its four layers; Application, Transport, Internet and Network Interface.
The Internet is also based on this model and includes lots of protocols which have various different uses.
The protocols that this model works with are; HTTP, HTTPS, FTP, POP3, SMTP, DNS, TCP and IP. Other protocols also exist.
Layer 1 - Network Interface
Layer 1 - Network Interface revolves around user interaction and presentation of data. It is also responsible for implementing packets on the network and also receiving them. TCP/IP was developed to be independent on the network and because of this it is used to connect to different network types. The network types are mostly LAN networks, such as; Ethernet, WAN and Token passing.
Layer 2 - Internet
Layer 2 - Internet, organises moving data on a network and it is also responsible for various different functions, the main protocol of this layer is IP (Internet Protocol), and on its own, allows the user to address a package and place into the system, however, there isn't a direct link between the user and the recipient. However, when the IP protocol is part of TCP/IP is allows a connection between the two people meaning they can send data back and forth for a period of time.
Layer 3 - Transport
Layer 3 - Transport is responsible for providing the Application layer with session and datagram communication services. The main protocols of this layer are TCP and UDP (User Datagram Protocol).
Layer 4 - Application
Layer 4 - Application provides applications the ability to access services from other layers and then defines the protocols that the applications use to exchange data. Although there are already many Application layer protocols, more are always being developed.
Protocols
In this next section I will be talking about protocols, which are a series of rules used between multiple computer systems when communicating amongst each other or transferring data across the network. The protocols I will be talking about will be wireless, including; WI-FI, 3G, 4G and other wireless security protocols.
Protocols are important because they allow a set of boundaries or guidelines to be set for a series of computer systems and other devices on a network. Without protocols, there would be no rules which ultimately means that nothing would function according to how it is supposed to. For example without protocols, there would be no error detection or correction, data would not be split up into smaller sections known as packets and datagrams.
Each individual protocol is important and necessary in its own specific way because they all function for multiple mediums and uses and they also all incorporate different security measures and various particular ways of completing the same or similar job.
Wi-Fi
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| Figure 2. TCP/IP Four Layer Model (SHawes, 2015) |
In the image to the left (see Figure 2.), it shows the TCP/IP model with its four layers; Application, Transport, Internet and Network Interface.
The Internet is also based on this model and includes lots of protocols which have various different uses.
The protocols that this model works with are; HTTP, HTTPS, FTP, POP3, SMTP, DNS, TCP and IP. Other protocols also exist.
Layer 1 - Network Interface
Layer 1 - Network Interface revolves around user interaction and presentation of data. It is also responsible for implementing packets on the network and also receiving them. TCP/IP was developed to be independent on the network and because of this it is used to connect to different network types. The network types are mostly LAN networks, such as; Ethernet, WAN and Token passing.
Layer 2 - Internet
Layer 2 - Internet, organises moving data on a network and it is also responsible for various different functions, the main protocol of this layer is IP (Internet Protocol), and on its own, allows the user to address a package and place into the system, however, there isn't a direct link between the user and the recipient. However, when the IP protocol is part of TCP/IP is allows a connection between the two people meaning they can send data back and forth for a period of time.
Layer 3 - Transport
Layer 3 - Transport is responsible for providing the Application layer with session and datagram communication services. The main protocols of this layer are TCP and UDP (User Datagram Protocol).
Layer 4 - Application
Layer 4 - Application provides applications the ability to access services from other layers and then defines the protocols that the applications use to exchange data. Although there are already many Application layer protocols, more are always being developed.
Protocols
In this next section I will be talking about protocols, which are a series of rules used between multiple computer systems when communicating amongst each other or transferring data across the network. The protocols I will be talking about will be wireless, including; WI-FI, 3G, 4G and other wireless security protocols.
Protocols are important because they allow a set of boundaries or guidelines to be set for a series of computer systems and other devices on a network. Without protocols, there would be no rules which ultimately means that nothing would function according to how it is supposed to. For example without protocols, there would be no error detection or correction, data would not be split up into smaller sections known as packets and datagrams.
Each individual protocol is important and necessary in its own specific way because they all function for multiple mediums and uses and they also all incorporate different security measures and various particular ways of completing the same or similar job.
Wi-Fi
WI-FI is a wireless networking technology that incorporates the use of radio waves in order to transmit data across the network. This protocol covers a family of wireless standards known as 802.11 which group all wireless technologies together.
802.11g
802.11g is a form of WI-FI that was made official in 2003 as an IEEE standard. 802.11g supports Wireless Local Area Network (WLAN) communications among various systems, such as; computers, routers and other compatible devices.
This also replaces the previous, older version, which was 802.11b, which was introduced in 1999 and has now been rendered discontinued/obsolete.
The performance for 802.11g WI-FI in comparison with 802.11b is exceptional, because it supports the maximum network bandwidth, which is 54MB/s compared to the lower 11MB/s which was dedicated to 802.11b. In order to maintain backward compatibility with older WI-FI devices, the 802.11g uses the same range frequency as the 802.11g, which is 2.4GHz.
802.11n
Carrying on from 802.11g, 802.11n was released by adding multiple inputs and outputs. Due to the addition of a transmitter and an antenna this allows for increased data throughout. The speed is 100MB/s which is double the speed of 802.11g. 802.11n also has better coverage than other current networks.
WiGig
WiGig is a new technology that is based upon the IEEE 802.11ad specification, this technology can support data that has transfer speeds of upto 7GB/s, which is the fastest 802.11 technology yet. Unlike other earlier specifications such as 802.11n that operated at 2.4GHz, WiGig operates at an exceptional 60GHz. Due to the higher frequency, WiGig's wavelengths are much shorter compared to other specifications, which unfortunately limits its range to about 30ft.
Bluetooth
Bluetooth or 802.15.1 is type of radio communication and wireless network protocol technology, the idea of Bluetooth is that one device is able to transfer data at a moderate speed to another device, bearing in mind that both devices are Bluetooth compatible.
The image above (see Figure 3.) is the logo of Bluetooth.
The original intention for Bluetooth technology was to make it possible for mobile phones to technologically communicate with a computer without the use of cables, a benefit of Bluetooth was being able to sit a short distance away from the other device, around 10 metres, even if there was a single wall in-between the two devices.
Many technologies have built-in Bluetooth, such as; gaming consoles, computers, mobile phones, controllers/remotes, wireless headsets and also some new cars; in cars Bluetooth is used to connect the driver's or passenger's phone to the sound-system (in-car music player).
Global System for Mobile Communications (GSM) - 3G and 4G
Global System for Mobile Communications or GSM is an open, digital mobile technology, which is used for making phone calls and using data services, such as; 3G, 4G and mobile Internet.
When talking about 2G, 3G or even the latest 4G, the G simply means generation, so when someone refers to one of the technologies, for example 3G, they are actually referring to a third-generation network technology.
When using a mobile device which has 3G capability, the technology allows for faster data and the ability for voice and data communication, and the new, latest 4G just increases the overall speed.
Wireless Security Protocols
The standards of a wireless network say there must be no security, which basically allows for the threat of viruses and malware. Wireless Security Protocols, such as; WEP, WPA, WPA2, were introduced to combat this threat and therefore provide protective coverage over all wireless networks. The job of a Wireless Security Protocol is to encrypt data which is on the wireless network, while it is being transmitted 'wirelessly'.
Wireless Encryption Protocol (WEP)
Wireless Encryption Protocol or WEP is part of the 802.11 wireless networking standard and it was developed to provide a similar level of security as of a WLAN (Wireless Local Area Network). Wireless networks were originally extremely difficult to protect and maintain an order of privacy, due to the data being transmitted among radio-waves which were and still are, susceptible to unauthorised, anonymous and invisible listeners.
However, it was found that WEP was actually insecure, meaning that a new form of security needed to be developed.
WI-FI Protected Access (WPA)
WI-FI Protected Access or WPA was developed to replace the insecure WEP WI-FI standard, the technology was developed to work with previously enabled WEP devices, meaning that new devices and systems were not needed. WPA was just a security replacement standard, that was an improvement upon WEP enabled devices, rather than a new technology altogether.
One of the main new features that had been implemented into WPA were integrity checks that determined if an unauthorised attack had captured or made unauthorised changes to packets which were passed between the access point and the user.
WI-FI Protected Access v2 (WPA2)
WI-FI Protected Access v2 or WPA2 was a replacement for its predecessor WPA and is also compatible with WPA devices. The new security standard included stronger data protection and network access control. It also provides the users with a high-level of assurance that only those who are authorised to be connected can access the wireless network.
There are two versions of WPA2, these are WPA2-Personal and WPA2-Enterprise. WPA2-Personal protects the network from unauthorised access by using a password which only the network's owner knows and those who he may tell the password to. WPA2-Enterprise verifies the users through a server before granting them access, Enterprise is usually used on-board public transport, such as buses and trains.
SkyNet-SH
Thank you once again for reviewing today's post regarding communication models protocols. Stay updated for the next edition of SkyNet's blog posts, next time I will be talking about 'data elements'.
References:
OSI Layer Descriptions - Webopedia.com, 2015. OSI Layers [online] Available at: http://www.webopedia.com/quick_ref/OSI_Layers.asp [Accessed 01/2015]
WiGig
WiGig is a new technology that is based upon the IEEE 802.11ad specification, this technology can support data that has transfer speeds of upto 7GB/s, which is the fastest 802.11 technology yet. Unlike other earlier specifications such as 802.11n that operated at 2.4GHz, WiGig operates at an exceptional 60GHz. Due to the higher frequency, WiGig's wavelengths are much shorter compared to other specifications, which unfortunately limits its range to about 30ft.
Bluetooth
Bluetooth or 802.15.1 is type of radio communication and wireless network protocol technology, the idea of Bluetooth is that one device is able to transfer data at a moderate speed to another device, bearing in mind that both devices are Bluetooth compatible.
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| Figure 3. Bluetooth Logo (Wikipedia.com, 2011) |
The image above (see Figure 3.) is the logo of Bluetooth.
The original intention for Bluetooth technology was to make it possible for mobile phones to technologically communicate with a computer without the use of cables, a benefit of Bluetooth was being able to sit a short distance away from the other device, around 10 metres, even if there was a single wall in-between the two devices.
Many technologies have built-in Bluetooth, such as; gaming consoles, computers, mobile phones, controllers/remotes, wireless headsets and also some new cars; in cars Bluetooth is used to connect the driver's or passenger's phone to the sound-system (in-car music player).
Global System for Mobile Communications (GSM) - 3G and 4G
Global System for Mobile Communications or GSM is an open, digital mobile technology, which is used for making phone calls and using data services, such as; 3G, 4G and mobile Internet.
When talking about 2G, 3G or even the latest 4G, the G simply means generation, so when someone refers to one of the technologies, for example 3G, they are actually referring to a third-generation network technology.
When using a mobile device which has 3G capability, the technology allows for faster data and the ability for voice and data communication, and the new, latest 4G just increases the overall speed.
Wireless Security Protocols
The standards of a wireless network say there must be no security, which basically allows for the threat of viruses and malware. Wireless Security Protocols, such as; WEP, WPA, WPA2, were introduced to combat this threat and therefore provide protective coverage over all wireless networks. The job of a Wireless Security Protocol is to encrypt data which is on the wireless network, while it is being transmitted 'wirelessly'.
Wireless Encryption Protocol (WEP)
Wireless Encryption Protocol or WEP is part of the 802.11 wireless networking standard and it was developed to provide a similar level of security as of a WLAN (Wireless Local Area Network). Wireless networks were originally extremely difficult to protect and maintain an order of privacy, due to the data being transmitted among radio-waves which were and still are, susceptible to unauthorised, anonymous and invisible listeners.
However, it was found that WEP was actually insecure, meaning that a new form of security needed to be developed.
WI-FI Protected Access (WPA)
WI-FI Protected Access or WPA was developed to replace the insecure WEP WI-FI standard, the technology was developed to work with previously enabled WEP devices, meaning that new devices and systems were not needed. WPA was just a security replacement standard, that was an improvement upon WEP enabled devices, rather than a new technology altogether.
One of the main new features that had been implemented into WPA were integrity checks that determined if an unauthorised attack had captured or made unauthorised changes to packets which were passed between the access point and the user.
WI-FI Protected Access v2 (WPA2)
WI-FI Protected Access v2 or WPA2 was a replacement for its predecessor WPA and is also compatible with WPA devices. The new security standard included stronger data protection and network access control. It also provides the users with a high-level of assurance that only those who are authorised to be connected can access the wireless network.
There are two versions of WPA2, these are WPA2-Personal and WPA2-Enterprise. WPA2-Personal protects the network from unauthorised access by using a password which only the network's owner knows and those who he may tell the password to. WPA2-Enterprise verifies the users through a server before granting them access, Enterprise is usually used on-board public transport, such as buses and trains.
SkyNet-SH
Thank you once again for reviewing today's post regarding communication models protocols. Stay updated for the next edition of SkyNet's blog posts, next time I will be talking about 'data elements'.
References:
OSI Layer Descriptions - Webopedia.com, 2015. OSI Layers [online] Available at: http://www.webopedia.com/quick_ref/OSI_Layers.asp [Accessed 01/2015]
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