Communication Models & Protocols

Communication Models & Protocols:

Introduction:

In this blog post, I will be explaining about the uses of communication models as well as what they are in general - such as the OSI model (Open System Interconnect) and the TCP/IP (Transmission Control Protocol/Internet Protocol. In addition, I will provide diagrams.

Afterwards, I will provide an explanations for the main protocols used in networks. Some protocol standards that the IEEE (Institute of Electrical and Electronic Engineering) looks after are:

• Wi-Fi (802.11g, 802.11n)
• Bluetooth
• 3G and 4G
• Wireless Security Protocols (WEP, WPA)

In general, communication protocols are essentially communication methods which can be interpreted as a rule or instructions to how data and information are transferred from one device to another. Communication protocols are very important because they are required in order for successful interactions between devices and models to be carried out, or otherwise it will not work as overall its purpose is to provide compatibility. Moreover, they each serve a role/function such as to aid a particular area, or help minimise risks etc – these “protocol standard has to be agreed” (Anderson et al, 2011) which means that in order for successful data transmission; the protocols set in place must go through its procedure accordingly. Examples of protocols shown below include the TCP (transmission control protocol) and IP (internet protocol) model. Hence the name, these protocols were invented to help the internet.

OSI Communication Model:

The OSI communication model (also referred to ‘Open System Interconnect’) is a seven layered model which is created as a method of explaining to people about the network’s structure and to ensure communication is reliable between network devices for all platforms for compatibility purposes. See figure 1 for a brief description of each layer.

• Layer 1, Physical: This is where all the hardware is located such as the cables for the transfer of binary data to the second layer. An example would be Ethernet.
• Layer 2, Data Link: This layer contains the addresses that give a unique identity to the device; this controls the access of data as well as permission to send data. An example of a physical address is a MAC address.
• Layer 3, Network: In this layer, the routing takes place by creating connection lines that link one node to another node – allowing data to be transferred.
• Layer 4, Transport: This layer has the responsibility to transport data from one place to the other without harmful data (viruses) to be imported with the aid of firewalls and protocols to detect data corruptions (acting as a traffic control too).
• Layer 5, Session: With this layer, the user will have the ability to open “multiple browser, chat and email windows open simultaneously without any conflicts in the data transmitted” (Anderson et al, 2011) as it manages the connections between applications (programs).
• Layer 6, Presentation: Hence the name of the layer, this layer presents by converting the data from the application to formats we can use and view, e.g. images in the file format of .JPEG.
• Layer 7, Application: This is the closest layer the user can interact with as this can control, monitor, and access the network services (explained in ‘Network Software’ blog). Moreover, this also allows application to send emails, use web browsers and have file transferred with the user’s command. Common examples would include HTTP, HTTPS and FTP.

Figure 1: OSI Model

TCP/IP Communication Model:

TCP/IP (also referred to ‘Transmission Control Protocol/Internet Protocol’) is a model which is identical to the OSI model but mainly represents how the internet works instead, differing it. Additionally, TCP/IP was created with the help of various other protocols (TCP and IP) whilst following the generic structure of the OSI model, resulting in four layers to also distinguish tasks for simplicity, (see figure 2).

Figure 2: OSI vs TCP/IP Comparison

Wi-Fi:

Wi-Fi is a wireless signal and is an important protocol because it allows data to be transferred and received between the router and the DTE (data terminal equipment) device, such as laptops, tablets and phones to connect to the internet. The IEEE (Institute of Electrical and Electronic Engineers) has many manages/controls which allow one system to communicate to another, one of which is 802.11g, and 802.11n: Wireless LAN (Wi-Fi). There are also other types such as a, b, g and n that defines connection speed of each. Additionally, a couple more examples of the 802 standards includes:

• 802.3 (Ethernet): Ethernet are found in cables and this could be considered as most reliable (speed wise) due to it being able to transmit data across multiple networks quickly.
• 802.5 (Token Ring): Operates within topologies such as a ring. Token ring performs token passing by sharing the ‘ring’ in turns and this avoids the impacts of data collision as each node will have its own access at some point.
• 802.15.1 (Bluetooth): Bluetooth is a standard method of transmitting data from one device to the other without the need for cables. This heavily relies on the line of sight and requires the devices to be within a certain radius and thus is slower than the others.

Bluetooth:

Bluetooth is another IEEE standard (802.15.1) for devices to communicate to each other. However, this only functions within a short radius of networking devices (e.g. if two mobile phones are nearby). This allows easy share of data to communicate between devices and also requires low power, making it convenient and a useful protocol.

3G and 4G:

3G and 4G are both similar protocols that allow devices such as smartphone to communicate and send data. As technology advances, improved generations (G) are produced to increase efficiency and speed. Usually GSM (Global System for Mobile Communications) gives the access to connect to their network for the ability to communicate via voice and data, 3G is the example of this as it allows both data and voice communication at the same time whereas 4G is the improved version of 3G with a promising speed from “10Mbps to 300Mbps”, (Anderson et al, 2011). 

Wireless Security Protocols (WEP, WPA):

To connect to a wireless network, the user must connect with no security and this will ensure connectivity according to the standards. As a result of this, other people have the chance to steal bandwidth/information from many homes and commercial wireless networks, resulting in slower connection.

Due to the lack of security, a wireless security protocols such as WEP (wired equivalent privacy) was invented to tackle this issue for LAN. WEP does this by encrypting every packets of the file as it is transmitted from the device to its destination, end to end. However, it was discovered that this is not the case as WEP only works in the first two layers of the OSI model – not promising full security. This led to WPA (Wi-Fi protected access) which is essentially an improved protocol of WEP by improving the encryption process as well as having additional new features.

Harvard Referencing: (In order of reference)
- Anderson, K. Atkinson-Beaumont, D.Kaye, A. Lawson, J. McGill, R. Phillips, J and Richardson, D. 2011. Information Technology Level 3 Book 1 BTEC National. Harlow: Pearson Education Limited.
- Figure 1: compnetworking.about, n.d. Basics_OSIModel. [Online] Available at: <http://compnetworking.about.com/library/graphics/basics_osimodel.jpg> [Accessed 21 January 2015].
- Figure 2: dret, n.d. OSI vs Internet. [Online] Available at: <http://dret.net/lectures/services-fall06/img/osi-vs-internet.gif> [Accessed 21 January 2015].

Bibliography: (In alphabetical order)
- webopedia, 2015. OSI Layers. [Online] Available at: <http://www.webopedia.com/quick_ref/OSI_Layers.asp> [Accessed 21 January 2015].
- support.microsoft, 2015. The OSI Model’s Seven Layers Defined and Functions Explained. [Online] Available at: <http://support.microsoft.com/kb/103884> [Accessed 21 January 2015].
- webopedia, 2015. TCP/IP – Transmission Control Protocol/Internet Protocol. [Online] Available at: <http://www.webopedia.com/TERM/T/TCP_IP.html> [Accessed 21 January 2015].
- webopedia, 2015. WEP – Wireless Equivalent Privacy. [Online] Available at: <http://www.webopedia.com/TERM/W/WEP.html> [Accessed 21 January 2015].
- webopedia, 2015. WPA – Wi-Fi Protected Access. [Online] Available at: <http://www.webopedia.com/TERM/W/WPA.html> [Accessed 21 January 2015].