TJ

Networking Project Part 1: Research and Planning

Topics covered:

Medium Access Control Sublayer

Circuit and Packet Switching

TCP/IP

OSI model

Medium Access Control Sublayer

Logical Link Control (LLC)

The data link layer has electronic; the LLC function (LLC) works within the LLC layer and the role of the LLC mechanism is to serve as an interface between the upper layers of the OSI model and the lower layers of the OSI model. First of all, it is the main purpose of providing data transfer between network devices that is reliable even if the units of hardware and the medium of a physical carrier are complicated. The LLC layer is responsible mainly for the header framing, ensuring flow control, performing error detection and correction, handling the addresses, and multiplexing onto a single physical data transmission (Crow et al., 1997). Enclosed with data packets into frames and having its sealing and resending backed up, LLC provides smooth communication between network layer protocols and applications. It communicates with higher layers of design it messages in such a way that would be properly packaged and transmitted and understood for further processing.

Media Access Control (MAC)

The MAC sublayer deals with regulating the use of the media for transmission in media networks with the device level being contention oriented. Similarly, In LANs, where broadcast communication is prevalent, MAC control protocol intensely restricts conflict of devices competing for the resource which is shared. MAC decides which device can send data at any particular moment, following the same processes of access control via the contention-based protocols or time scheduling. It does not just communicate upward but actually performs two-way transmission, orchestrating the process and ensuring a proper use of the physical medium (Han et al., 2012). MAC eases the access to media, but sending packets of data is not part of its remit which is something belonging from another layer of the protocol string.

Importance in LANs

MAC sublayer's role especially gains relevance in the situation of LAN applications, where nodes are situated near each other, and this communication is carried out with the help of broadcast channels. This condition facilitates the co-existence of the devices in the confined and common medium, which eventually triggers the congestion problems. MAC protocols define the way devices are allowed to use/communicate information being shared among them thus releasing network resources to prevent congestion.

Delivery Guarantee

In contrast with the transport or network layers that are located higher of the OSI architecture, the MAC sublayer doesn't provide guaranteed delivery of the data packets. Unlike the traditional model, where it is the main regulator of the transmission medium, the new model concerns itself with three issues: regulating access to the transmission medium, coordinating the transmission process, and determining what the 'best' transmitters are. MAC protocols are the ones that ensure an efficient data-sharing process, while the main task of high level protocols is to transfer the data packets correctly. Hence, LAN is associated with a low level of abstraction, unlike the higher one (MAC mode is concerned with access to the physical medium while End-to-End delivery guarantees data proceeding).

Dynamic Channel Allocation

Underlying Assumptions

Dynamic channel allocation (CCA) methods work under several underlying assumptions, but they are designed to govern the proper management of communication channels in changing network environments. The station model assumption describes the method of traffic individually operating through station stations by having data frames generated and deposited regularly. After a picture has been generated, one stabilizes the station until the picture is loaded up and then proceeds transmission orderly data transfer. The single-channel hypothesis reflects a situation where all communication procedures take place only on one channel, which all stations may use for the transmission and reception of data. That does the job of channel allocation and coordination, but there is a need for a contention management mechanism, too.

Collision assumption is a fair typification of the possibility of the collisions occurring when particular stations try to pass their data on a shared channel simultaneously. The humming of the channels and their resolution processes are essential the fairness regarding the access to the facilities and processing integrity in data. Besides numbered channel allocation, assumptions of continuous and slotted time are also considered (Cao & Lee, 2020). The continuous nature of time in cyclic timeslot allows the network to adjust the traffic change dynamically based upon different conditions on the network, while the slotted time of TDMA provides the capacity for transmission scheduling and coordination at a discrete time interval.

Channelization Protocols

Frequency Division Multiple Access (FDMA)

Frequency Division Multiple Access (FDMA) assigns each user a different frequency band out of the total frequency band and allows them to have individual conversations. Users conveying data in parallel over their assigned channel frequencies transfer their data, while every channel facilitates its path. FDMA is simple to employ and suitable for cases/situations where there is space to accommodate a moderate number of users. On the other hand, it may have very limited efficiency in the case of a large crowd, as the spectrum already being occupied becomes heavily crowded.

Time Division Multiple Access (TDMA)

The Time Division Multiple Access (TDMA) partitions the transmission time into distinct time slots, with each user allotted a specific time slot for data transmission, assigned to a specific time slot. The participants take turns to communicate data, albeit in their intervals, thus the highest level of utilization of the available bandwidth is verified. TDMA features the highly desirable property for traffic with these characteristics, to actively reconfigure its transmission resources on demand. However, users will likely find the time allocation rather overwhelming sometimes, especially in the case of dynamically changing networks.

Code Division Multiple Access (CDMA)

CDMA access code (CDMA) code which is unique for each user ensures that data transmission goes on simultaneously for all users at same frequency band. Every user's data broadcasted using a spreading code facilitates the decoding process as it determines the receivers whether the single transmission belong to them or some other person. CDMA provides higher spectral efficiency and narrow-band Interference resistance, thus CDMA was widely applied for mobile communication scenarios with very high user densities and bad radio propagation conditions. Although CDMA may provide ease of deployment and higher system capacity, it needs complex signal processing methods with careful coverage code management to have reliable communication functions.

The Medium Access Control (MAC) sublayer is a component of the Data Link Layer (Layer 2) in the OSI (Open Systems Interconnection) model. It coordinates access to the physical transmission medium, such as a network cable or wireless channel, in a shared communication environment. The MAC sublayer ensures that multiple devices connected to the same network can transmit data without causing collisions or interference.

Addressing: The MAC sublayer assigns unique hardware addresses, known as MAC addresses, to network interface cards (NICs) in devices connected to the LAN. MAC addresses are used to identify devices on the network.

Components of MAC sublayer

Access Control: The MAC sublayer manages how devices access the network medium to transmit data packets. It may use methods like Carrier Sense Multiple Access with Collision Detection (CSMA/CD) for Ethernet networks to avoid collisions when multiple devices attempt to transmit data simultaneously.

Frame Formatting: The MAC sublayer adds a header to data packets, including the source and destination MAC addresses, before transmitting them onto the network. This header is used by devices to determine where data packets should be sent and who sent them.

Error Detection: The MAC sublayer may include error detection mechanisms, such as a frame check sequence (FCS), to ensure the integrity of transmitted data and detect any errors or corruption that may occur during transmission.

Here is a quick analogy: Imagine a group therapy session where five people are connected through a Zoom meeting, and everyone can hear and talk to each other. When one person stops talking, it's common for two or more people to start talking at the same time, confusing. In a face-to-face setting, this confusion could be prevented using raising their hands or other ways but it is different during a Zoom meeting or even a multiway phone call. This is where the MAC sublayer comes into place.

Advantages and Disadvantages of the MAC sublayer:

Advantages

· Efficient Access: MAC efficiently shares the network, preventing conflicts.

· Fairness: It ensures everyone gets a fair turn on the network.

· Error Detection: It spots and fixes transmission errors.

· Flexibility: It works with different types of networks and setups.

· Scalability: It can handle many devices on a network.

Disadvantages:

· Bandwidth Limits: In busy networks, it can slow things down.

· Collisions: Devices talking at once can cause issues.

· Complexity: It can be hard to set up and manage.

· Security Risks: It might have vulnerabilities to attacks.

· Overhead: It adds extra data that can eat into bandwidth.

Citations

Tanenbaum, Andrew S., 1944- Computer networks / Andrew S. Tanenbaum, David J. Wetherall. -- 5th ed. https://www.imperva.com/learn/application-security/osi-model/https://visagurukul.com/blog/mac-full-formhttps://www.geeksforgeeks.org/difference-between-circuit-switching-and-packet-switching/https://www.geeksforgeeks.org/tcp-ip-model/

Crow, B. P., Widjaja, I., Kim, J. G., & Sakai, P. (1997, April). Investigation of the IEEE 802.11 medium access control (MAC) sublayer functions. In  Proceedings of INFOCOM'97 (Vol. 1, pp. 126-133). IEEE. https://doi.org/10.1109/INFCOM.1997.635122

Han, C., Dianati, M., Tafazolli, R., Kernchen, R., & Shen, X. (2012). Analytical study of the IEEE 802.11 p MAC sublayer in vehicular networks.  IEEE Transactions on Intelligent Transportation Systems,  13(2), 873-886. https://doi.org/10.1109/TITS.2012.2183366

Cao, S., & Lee, V. C. (2020). An accurate and complete performance modeling of the IEEE 802.11 p MAC sublayer for VANET.  Computer Communications,  149, 107-120. https://doi.org/10.1016/j.comcom.2019.08.026

Travis James

Networking Project Part 1: Research and Planning

Topics covered:

Medium Access Control Sublayer

Circuit and Packet Switching

TCP/IP

OSI model

Medium Access Control Sublayer

Logical Link Control (LLC)

The data link layer has electronic; the LLC function (LLC) works within the LLC layer and the role of the LLC mechanism is to serve as an interface between the upper layers of the OSI model and the lower layers of the OSI model. First of all, it is the main purpose of providing data transfer between network devices that is reliable even if the units of hardware and the medium of a physical carrier are complicated. The LLC layer is responsible mainly for the header framing, ensuring flow control, performing error detection and correction, handling the addresses, and multiplexing onto a single physical data transmission (Crow et al., 1997). Enclosed with data packets into frames and having its sealing and resending backed up, LLC provides smooth communication between network layer protocols and applications. It communicates with higher layers of design it messages in such a way that would be properly packaged and transmitted and understood for further processing.

Media Access Control (MAC)

The MAC sublayer deals with regulating the use of the media for transmission in media networks with the device level being contention oriented. Similarly, In LANs, where broadcast communication is prevalent, MAC control protocol intensely restricts conflict of devices competing for the resource which is shared. MAC decides which device can send data at any particular moment, following the same processes of access control via the contention-based protocols or time scheduling. It does not just communicate upward but actually performs two-way transmission, orchestrating the process and ensuring a proper use of the physical medium (Han et al., 2012). MAC eases the access to media, but sending packets of data is not part of its remit which is something belonging from another layer of the protocol string.

Importance in LANs

MAC sublayer's role especially gains relevance in the situation of LAN applications, where nodes are situated near each other, and this communication is carried out with the help of broadcast channels. This condition facilitates the co-existence of the devices in the confined and common medium, which eventually triggers the congestion problems. MAC protocols define the way devices are allowed to use/communicate information being shared among them thus releasing network resources to prevent congestion.

Delivery Guarantee

In contrast with the transport or network layers that are located higher of the OSI architecture, the MAC sublayer doesn't provide guaranteed delivery of the data packets. Unlike the traditional model, where it is the main regulator of the transmission medium, the new model concerns itself with three issues: regulating access to the transmission medium, coordinating the transmission process, and determining what the 'best' transmitters are. MAC protocols are the ones that ensure an efficient data-sharing process, while the main task of high level protocols is to transfer the data packets correctly. Hence, LAN is associated with a low level of abstraction, unlike the higher one (MAC mode is concerned with access to the physical medium while End-to-End delivery guarantees data proceeding).

Dynamic Channel Allocation

Underlying Assumptions

Dynamic channel allocation (CCA) methods work under several underlying assumptions, but they are designed to govern the proper management of communication channels in changing network environments. The station model assumption describes the method of traffic individually operating through station stations by having data frames generated and deposited regularly. After a picture has been generated, one stabilizes the station until the picture is loaded up and then proceeds transmission orderly data transfer. The single-channel hypothesis reflects a situation where all communication procedures take place only on one channel, which all stations may use for the transmission and reception of data. That does the job of channel allocation and coordination, but there is a need for a contention management mechanism, too.

Collision assumption is a fair typification of the possibility of the collisions occurring when particular stations try to pass their data on a shared channel simultaneously. The humming of the channels and their resolution processes are essential the fairness regarding the access to the facilities and processing integrity in data. Besides numbered channel allocation, assumptions of continuous and slotted time are also considered (Cao & Lee, 2020). The continuous nature of time in cyclic timeslot allows the network to adjust the traffic change dynamically based upon different conditions on the network, while the slotted time of TDMA provides the capacity for transmission scheduling and coordination at a discrete time interval.

Channelization Protocols

Frequency Division Multiple Access (FDMA)

Frequency Division Multiple Access (FDMA) assigns each user a different frequency band out of the total frequency band and allows them to have individual conversations. Users conveying data in parallel over their assigned channel frequencies transfer their data, while every channel facilitates its path. FDMA is simple to employ and suitable for cases/situations where there is space to accommodate a moderate number of users. On the other hand, it may have very limited efficiency in the case of a large crowd, as the spectrum already being occupied becomes heavily crowded.

Time Division Multiple Access (TDMA)

The Time Division Multiple Access (TDMA) partitions the transmission time into distinct time slots, with each user allotted a specific time slot for data transmission, assigned to a specific time slot. The participants take turns to communicate data, albeit in their intervals, thus the highest level of utilization of the available bandwidth is verified. TDMA features the highly desirable property for traffic with these characteristics, to actively reconfigure its transmission resources on demand. However, users will likely find the time allocation rather overwhelming sometimes, especially in the case of dynamically changing networks.

Code Division Multiple Access (CDMA)

CDMA access code (CDMA) code which is unique for each user ensures that data transmission goes on simultaneously for all users at same frequency band. Every user's data broadcasted using a spreading code facilitates the decoding process as it determines the receivers whether the single transmission belong to them or some other person. CDMA provides higher spectral efficiency and narrow-band Interference resistance, thus CDMA was widely applied for mobile communication scenarios with very high user densities and bad radio propagation conditions. Although CDMA may provide ease of deployment and higher system capacity, it needs complex signal processing methods with careful coverage code management to have reliable communication functions.

The Medium Access Control (MAC) sublayer is a component of the Data Link Layer (Layer 2) in the OSI (Open Systems Interconnection) model. It coordinates access to the physical transmission medium, such as a network cable or wireless channel, in a shared communication environment. The MAC sublayer ensures that multiple devices connected to the same network can transmit data without causing collisions or interference.

Addressing: The MAC sublayer assigns unique hardware addresses, known as MAC addresses, to network interface cards (NICs) in devices connected to the LAN. MAC addresses are used to identify devices on the network.

Components of MAC sublayer

Access Control: The MAC sublayer manages how devices access the network medium to transmit data packets. It may use methods like Carrier Sense Multiple Access with Collision Detection (CSMA/CD) for Ethernet networks to avoid collisions when multiple devices attempt to transmit data simultaneously.

Frame Formatting: The MAC sublayer adds a header to data packets, including the source and destination MAC addresses, before transmitting them onto the network. This header is used by devices to determine where data packets should be sent and who sent them.

Error Detection: The MAC sublayer may include error detection mechanisms, such as a frame check sequence (FCS), to ensure the integrity of transmitted data and detect any errors or corruption that may occur during transmission.

Here is a quick analogy: Imagine a group therapy session where five people are connected through a Zoom meeting, and everyone can hear and talk to each other. When one person stops talking, it's common for two or more people to start talking at the same time, confusing. In a face-to-face setting, this confusion could be prevented using raising their hands or other ways but it is different during a Zoom meeting or even a multiway phone call. This is where the MAC sublayer comes into place.

Advantages and Disadvantages of the MAC sublayer:

Advantages

1. Efficient Access: MAC efficiently shares the network, preventing conflicts.

2. Fairness: It ensures everyone gets a fair turn on the network.

3. Error Detection: It spots and fixes transmission errors.

4. Flexibility: It works with different types of networks and setups.

5. Scalability: It can handle many devices on a network.

Disadvantages:

1. Bandwidth Limits: In busy networks, it can slow things down.

2. Collisions: Devices talking at once can cause issues.

3. Complexity: It can be hard to set up and manage.

4. Security Risks: It might have vulnerabilities to attacks.

5. Overhead: It adds extra data that can eat into bandwidth.

Citations

Tanenbaum, Andrew S., 1944- Computer networks / Andrew S. Tanenbaum, David J. Wetherall. -- 5th ed. https://www.imperva.com/learn/application-security/osi-model/ https://visagurukul.com/blog/mac-full-form https://www.geeksforgeeks.org/difference-between-circuit-switching-and-packet-switching/ https://www.geeksforgeeks.org/tcp-ip-model/

Crow, B. P., Widjaja, I., Kim, J. G., & Sakai, P. (1997, April). Investigation of the IEEE 802.11 medium access control (MAC) sublayer functions. In  Proceedings of INFOCOM'97 (Vol. 1, pp. 126-133). IEEE. https://doi.org/10.1109/INFCOM.1997.635122

Han, C., Dianati, M., Tafazolli, R., Kernchen, R., & Shen, X. (2012). Analytical study of the IEEE 802.11 p MAC sublayer in vehicular networks.  IEEE Transactions on Intelligent Transportation Systems,  13(2), 873-886. https://doi.org/10.1109/TITS.2012.2183366

Cao, S., & Lee, V. C. (2020). An accurate and complete performance modeling of the IEEE 802.11 p MAC sublayer for VANET.  Computer Communications,  149, 107-120. https://doi.org/10.1016/j.comcom.2019.08.026