Multiple Access Control Layers in computer network.pptx

Multiple Access Control Layers refer to the implementation of several security mechanisms at different levels (e.g., network, application, data) to ensure comprehensive protection. This layered approach mitigates risks by adding redundancy and minimizing the impact of a single security failure.

1. Multiple Access Control Layers Prof. Trupti Sisode.

2. Wireless Local Area Network A Wireless Local Area Network (WLAN) is a type of local area network (LAN) that uses wireless communication to connect devices within a limited area, such as a home, office, or campus. Key Characteristics of WLAN Wireless Communication Radio Waves : WLANs use radio waves to transmit data between devices without the need for physical cables. This allows for greater mobility and flexibility. Frequency Bands : WLANs typically operate in the 2.4 GHz and 5 GHz frequency bands, with newer standards also using the 6 GHz band.

3. Limited Area Coverage Range : WLANs cover a relatively small geographical area, usually within a few hundred meters. The range can be extended using additional access points. Environment : The range and performance of a WLAN can be affected by physical obstacles, interference, and the quality of the equipment used. Components of a WLAN Access Points (APs) eg. Router : Devices that act as hubs for wireless devices to connect to the network. They connect to the wired network and manage wireless communication. Wireless Clients : Devices that connect to the WLAN, such as laptops, smartphones, tablets, printers, and IoT devices. Network Interface Cards (NICs) : Hardware components in wireless clients that enable them to connect to the WLAN.

4. How WLAN Works Signal Transmission Access Point Broadcasts : The access point sends out a signal, called a beacon, that announces the availability of the wireless network. This signal includes the network name (SSID) and other information. Client Devices Scan : Wireless clients in the area scan for available networks by looking for these beacons. Connecting to the Network Selecting a Network : The user selects the desired network on their device. For example, they might choose their home Wi-Fi network from a list. Association Request : The client device sends a request to the access point to join the network. Authentication : If the network is secured, the client must provide the correct password or passphrase. This ensures that only authorized devices can connect.

5. Data Transmission Sending Data : Once connected, the client device can send and receive data wirelessly through the access point. Access Point Role : The access point receives data from the client device, converts it into a format suitable for the wired network (if needed), and forwards it to the intended destination (like a website server). Receiving Data Data from the Internet : When data is sent back to the client device (such as a webpage being loaded), the access point receives this data from the wired network and transmits it wirelessly to the client. Maintaining Connection Roaming : If a client moves around within the coverage area, it may switch from one access point to another (if multiple APs are available) while maintaining its connection to the network.

6. Applications of WLAN Applications of WLAN Home Networking : Connecting multiple devices like smartphones, laptops, tablets, and smart home devices. Office Networking : Enabling employees to connect laptops, tablets, and mobile devices to the corporate network. Public Wi-Fi : Providing internet access in public places like cafes, airports, hotels, and libraries. Educational Institutions : Allowing students and faculty to access the network and internet across the campus.

7. What is IEEE? IEEE stands for the Institute of Electrical and Electronics Engineers. It is a global professional organization dedicated to advancing technology for the benefit of humanity. IEEE brings together engineers, scientists, and allied professionals from various disciplines related to electrical engineering, electronics, computer science, and related fields . The organization plays a crucial role in developing standards, fostering innovation, and providing educational resources and networking opportunities to its members worldwide.

8. Wired LANs: Ethernet IEEE STANDARDS In 1985, the Computer Society of the IEEE started a project, called Project 802, to set standards to enable intercommunication among equipment from a variety of manufacturers. Project 802 is a way of specifying functions of the physical layer and the data link layer of major LAN protocols. Topics discussed in this section: Data Link Layer Physical Layer

9. IEEE Standard Layers The IEEE standard breaks down network communication into specific protocols and physical characteristics for different types of networks. The LLC sublayer is common and provides essential functions for data link control. The MAC sublayer varies depending on the network type and manages access to the network medium. The physical layer defines the actual hardware specifications for transmitting data. This structure allows different network technologies to operate efficiently and communicate effectively

10. IEEE standard for LANs

11. IEEE Standard Layers 1. Upper Layers These are layers above the data link layer, just like in the OSI model. They include the network layer, transport layer, session layer, presentation layer, and application layer, which handle tasks such as routing, data transfer, session management, and user applications. 2. Data Link Layer This layer is split into two sublayers: Logical Link Control (LLC) and Media Access Control (MAC) . Logical Link Control (LLC): The LLC sublayer is the same across different types of networks. It acts as an interface between the upper layers and the MAC sublayer. Its main functions are to provide flow control, error control, and frame synchronization. It identifies the network layer protocol and encapsulates it, ensuring the data is formatted correctly for transmission.

12. Media Access Control (MAC): The MAC sublayer is different for various types of networks. It controls how devices on the network gain access to the medium and permission to transmit data. Different types of MAC sublayers include: Ethernet MAC: Used in Ethernet networks, which are the most common type of local area network (LAN). Ethernet uses protocols such as CSMA/CD (Carrier Sense Multiple Access with Collision Detection) to manage data transmission. Token Ring MAC: Used in Token Ring networks, where devices take turns to send data using a token-passing protocol. This helps avoid collisions and ensures orderly communication. Token Bus MAC: Used in Token Bus networks, similar to Token Ring but using a bus topology where devices share a common transmission medium and pass a token along the bus to control access. Other MAC types: This placeholder indicates that there can be other types of MAC sublayers for different network technologies.

13. 3. Physical Layer The physical layer in the IEEE standard is also specific to the type of network and defines the physical and electrical specifications for devices. Examples of Physical Layers: Ethernet Physical Layers: Different types of Ethernet have different physical layer specifications, such as 10BASE-T (10 Mbps over twisted pair cables), 100BASE-TX (100 Mbps over twisted pair cables), 1000BASE-T (1 Gbps over twisted pair cables), etc. Token Ring Physical Layer: Specifies the physical medium and electrical characteristics for Token Ring networks, which typically use twisted pair or fiber optic cables. Token Bus Physical Layer: Defines the physical medium for Token Bus networks, which might use coaxial cable or other types of transmission media. Other Physical Layers: This placeholder indicates that other physical layer specifications exist for other network technologies. Transmission Medium This represents the actual physical medium through which data is transmitted. It could be various types of cables (twisted pair, coaxial, fiber optic) or wireless media.

14. STANDARD ETHERNET The original Ethernet was created in 1976 at Xerox’s Palo Alto Research Center (PARC). Since then, it has gone through four generations. We briefly discuss the Standard (or traditional) Ethernet in this section. Topics discussed in this section: MAC Sublayer Physical Layer

15. 802.3 MAC frame -1983

16. Preamble (7 bytes) Purpose : The preamble is crucial for the synchronization of the communication between the sending and receiving devices. It ensures that both devices are ready to start interpreting the data that follows. Contents : The preamble consists of 7 bytes, each byte containing the pattern 10101010 in binary . Why Alternating 1s and 0s? : The alternating pattern of 1s and 0s creates a regular, predictable signal that the receiving device can detect easily. This helps the receiving device to lock onto the signal timing and synchronize its clock with the sender’s clock. Example ; Imagine you are at a concert and you know that the band will start playing at a specific time. To make sure you are ready, you start listening for a signal, like a countdown or a sound check. Similarly, in Ethernet communication: Synchronization : When the sending device starts transmitting, it sends the preamble first. The receiving device, upon detecting the preamble, starts synchronizing its timing to match the sender’s timing. The regular pattern of the preamble helps the receiving device align its internal clock with the signal from the sending device. Reliable Communication : Without the preamble, the receiver might miss the beginning of the frame, leading to errors in interpreting the data. The preamble ensures that the receiver is ready and synchronized by the time the actual data starts arriving. Preamble: 10101010 10101010 10101010 10101010 10101010 10101010 10101010 (7 bytes of alternating 1s and 0s)

17. Start Frame Delimiter (SFD) (1 byte) Purpose : The SFD marks the end of the preamble and indicates the start of the actual Ethernet frame. It signals to the receiving device that the data following this byte is the actual frame data. Contents : The SFD consists of one byte with the binary pattern 10101011 . Explanation Imagine you're listening to a countdown before a race. The countdown might go "3, 2, 1, GO!" The "GO!" tells you the race has started. Similarly, the SFD tells the receiving device that the preamble has ended and the real data is about to begin. Preamble: 10101010 10101010 10101010 10101010 10101010 10101010 10101010 (7 bytes of alternating 1s and 0s) SFD: 10101011 (1 byte marking the start of the frame) In Simple Terms : The preamble is like a series of beeps getting the receiver ready. The SFD is like a final, slightly different beep that says, "Here comes the real message!" Once the receiver detects the SFD ( 10101011 ), it knows that the actual Ethernet frame data is about to start, ensuring accurate data transmission and reception.

18. Destination MAC Address (6 bytes) Purpose : The Destination MAC Address tells the network which specific device should receive the Ethernet frame. Contents : It is a 6-byte (48-bit) address that is unique to each device’s network interface card (NIC). Explanation Imagine sending a letter by mail. You need to write the recipient's address on the envelope so the postal service knows where to deliver it. The Destination MAC Address works the same way for Ethernet frames. Here’s how it works: Unique Address : Each device on a network has a unique MAC address, just like each house has a unique postal address. The MAC address is assigned to the device’s NIC by the manufacturer. Format : A MAC address is 48 bits long, typically written as 12 hexadecimal digits. For example, 00:1A:2B:3C:4D:5E . Role in Data Transmission : When an Ethernet frame is sent over a network, it includes the Destination MAC Address. Network devices (like switches) use this address to determine where to forward the frame, ensuring it reaches the correct device. In Simple Terms : Think of the Destination MAC Address as the “to” address on an envelope. It tells the network exactly which device should receive the message. This unique address ensures that the data sent through the network arrives at the correct device, much like a postal address ensures that a letter reaches the right house.

19. What is a NIC? Network Interface Card (NIC) : A NIC is a physical piece of hardware installed in a device (like a computer, server, or printer) that enables it to communicate over a network. It can be an internal component, like a card inserted into a computer's motherboard, or an external device connected via USB or other interfaces. Primary Functions of a NIC Connecting to a Network : Wired Networks : An Ethernet NIC connects a device to a wired network using an Ethernet cable. Wireless Networks : A Wi-Fi NIC connects a device to a wireless network. Data Transmission : The NIC sends and receives data packets over the network. It converts data from the device into signals that can be transmitted over the network medium (Ethernet or Wi-Fi) and vice versa. MAC Address : Each NIC has a unique Media Access Control (MAC) address, which is used to identify the device on the network. Network Protocols : NICs support various network protocols (e.g., TCP/IP), ensuring proper communication and data exchange between devices. Types of NICs : Ethernet NIC : Used for wired network connections. It has an Ethernet port to connect with an Ethernet cable. Wireless NIC : Used for wireless network connections. It connects to Wi-Fi networks. Combo NIC : Some NICs can support both wired and wireless connections.

20. Source MAC Address (6 bytes) : Specifies the address of the NIC that is sending the frame. Also a 48-bit address unique to each device. Ether Type/Length (2 bytes) : Purpose : Specifies the type of protocol that is being carried in the frame’s payload. Example Values : 0x0800 for IPv4 Ether Type: 0800 (indicates IPv4 protocol) 0x86DD for IPv6 0x0806 for ARP (Address Resolution Protocol) How It Works : When using Ethernet II frames, this field tells the receiving device which protocol is being used so it knows how to process the data. Payload/Data (46 to 1500 bytes) ( Data and Padding): Description: Contains the payload data. Padding is added if the data is less than 46 bytes to meet the minimum Ethernet frame size requirement. Purpose: The actual data being transmitted, such as an IP packet.

21. Frame Check Sequence (FCS) (4 bytes) Purpose : The FCS is used to detect errors in the Ethernet frame. It helps ensure that the data was not corrupted during transmission. How It Works : Error Detection : When a frame is sent, the sender calculates a special value called the CRC (Cyclic Redundancy Check) based on the contents of the frame. This CRC value is added to the end of the frame as the FCS. Verification : When the receiver gets the frame, it performs the same CRC calculation on the received data (excluding the FCS). It then compares this calculated CRC with the FCS value in the frame. If the calculated CRC matches the FCS, the frame is considered to be error-free. If they don't match, it means there was an error during transmission. Physical Layer Header: The preamble and SFD together form the physical layer header. These are used to prepare the physical medium for data transmission and ensure synchronization.

22. Minimum and maximum lengths

23. Example of an Ethernet address in hexadecimal notation

24. Ethernet evolution through four generations

25. Standard Ethernet (10 Mbps) Introduction Year: Early 1980s Standard: IEEE 802.3 Cabling: Originally used coaxial cable (10BASE5 and 10BASE2) and later twisted pair (10BASE-T). Usage: It was the first widely adopted networking standard, used primarily in local area networks (LANs). Transmission Method: Uses Carrier Sense Multiple Access with Collision Detection (CSMA/CD) to manage data packets on the network.

26. Fast Ethernet (100 Mbps) Introduction Year: 1995 Standard: IEEE 802.3u Cabling: Uses twisted pair cables (100BASE-TX) and Fiber optics (100BASE-FX). Usage: Provided a tenfold increase in speed over Standard Ethernet, allowing for faster data transfer in growing networks. Transmission Method: Also uses CSMA/CD but is designed to be backward compatible with 10 Mbps Ethernet, enabling easier upgrades.

27. Types of Fast Ethernet

28. Gigabit Ethernet (1 Gbps) Introduction Year: 1999 Standard: IEEE 802.3z (fiber) and IEEE 802.3ab (twisted pair) Cabling: Uses fiber optic cables (1000BASE-SX, 1000BASE-LX) and twisted pair cables (1000BASE-T). Usage: Suitable for high-speed backbone connections, server connections, and demanding applications like video conferencing. Transmission Method: Supports both full-duplex and half-duplex operations but is typically used in full-duplex mode to eliminate collisions.

29. Gigabit Ethernet implementations

30. Ten-Gigabit Ethernet (10 Gbps) Introduction Year: 2002 Standard: IEEE 802.3ae (Fiber), IEEE 802.3an (twisted pair) Cabling: Uses various types of Fiber optic cables (10GBASE-SR, 10GBASE-LR, 10GBASE-ER) and twisted pair cables (10GBASE-T). Usage: Designed for data centers , high-performance computing networks, and enterprise backbones, where extremely high-speed data transfer is critical. Transmission Method: Primarily used in full-duplex mode, supporting advanced applications and heavy data loads.

31. Categories of Standard Ethernet Star Fiber

32. Encoding in a Standard Ethernet implementation Manchester encoding is a method of encoding digital data for transmission over a medium. It combines the data and clock signals into a single bitstream, which helps in synchronization and error detection.

33. 10Base5 implementation

34. 10Base2 implementation

35. 10Base-T implementation

36. 10Base-F implementation

37. Summary of Standard Ethernet implementations 13. 38

38. CHANGES IN THE STANDARD Bridged Ethernet Definition: A network setup where multiple Ethernet segments are connected using network bridges. Function: Bridges filter traffic by examining the MAC addresses of incoming frames and forwarding them only to the appropriate segment. This reduces unnecessary traffic. Advantages: Reduces collision domains by segmenting the network. Enhances network performance and efficiency.

39. Sharing bandwidth Gaps between frames are important to avoid collisions and ensure proper processing and synchronization in network communication. They also help in managing flow control and maintaining network efficiency.

40. A network with and without a bridge

41. Collision domains in an unbridged network and a bridged network

42. Switched Ethernet Definition: A network setup that uses Ethernet switches instead of hubs or bridges to connect devices. Function: Switches operate at the data link layer and use MAC addresses to forward frames only to the specific port that leads to the destination device.

43. Switched Ethernet

44. Full-duplex switched Ethernet

45. Importance of IEEE 802.11 A WLAN is a network that uses wireless communication to connect devices within a limited area, providing flexibility, mobility, and ease of installation. It relies on standards like IEEE 802.11 to ensure compatibility and security across different devices and networks. WLAN uses these established IEEE 802.11 standards to function correctly. The IEEE 802.11 standards provide the rules and specifications that guide how wireless networks operate, ensuring that devices can communicate effectively and securely over wireless connections.

46. Wireless LAN: IEEE 802.11 IEEE 802.11, commonly known as Wi-Fi, is a set of standards for wireless networking. Wi-Fi allows devices like computers, smartphones, and tablets to connect to the Internet and to each other without the need for physical cables. How Wi-Fi Works: Access Points and Routers : Wi-Fi networks are typically set up using devices called routers or access points. These devices connect to the Internet through a wired connection and then broadcast a wireless signal. Wireless Signal : The wireless signal is a form of radio waves. Devices within range, like your phone or laptop, can detect this signal and connect to the network. Connection Process : When a device wants to connect to a Wi-Fi network, it searches for available networks. Once it finds a network, it can connect using a password if the network is secured. Data Transmission : After connecting, data can be sent back and forth between the device and the Internet through the router. This data includes everything from web pages and emails to streaming videos.

47. Basic service sets (BSSs)

48. . Ad Hoc Network (BSS without an AP) Definition : An ad hoc network, also known as an Independent Basic Service Set (IBSS), is a type of wireless network where stations (devices) communicate directly with each other without the need for an access point (AP). Characteristics : No Access Point : There is no central device managing the network. Peer-to-Peer Communication : Each station can communicate directly with any other station within its range. Flexibility : Suitable for temporary or small-scale networks where setting up an AP is unnecessary or impractical. Decentralized : No single point of failure; if one station fails, others can still communicate.

49. Infrastructure Network (BSS with an AP) Definition : An infrastructure network, or Infrastructure Basic Service Set (BSS), involves stations connecting to each other through an access point (AP). Characteristics : Access Point (AP) : Central device that manages the communication and connectivity of all stations within the BSS. Centralized Control : The AP facilitates communication between stations, even if they are out of each other's direct communication range. Extended Range and Connectivity : The AP can connect to a distribution system (e.g., Ethernet), allowing stations to communicate with other networks or BSSs. Security and Management : Easier to implement security measures and manage the network through the AP.

50. Extended service sets (ESSs)

51. Basic Service Set (BSS) : A BSS is the fundamental building block of an IEEE 802.11 wireless network. It consists of a group of stations (e.g., laptops, smartphones) that communicate with each other. Each BSS can operate in either ad hoc mode (without an access point, not shown here) or infrastructure mode (with an access point, as shown in the image). Access Point (AP) : The AP acts as a central hub in a BSS operating in infrastructure mode. It manages communication between stations and connects them to the distribution system (DS). Each BSS in the image has its own AP. Distribution System (DS) : The DS is a network that connects multiple APs, allowing them to form an ESS. It typically uses wired network technologies such as Ethernet. The DS facilitates communication between stations in different BSSs and provides connectivity to external networks, including the Internet. Extended Service Set (ESS) : An ESS is a set of interconnected BSSs, allowing for larger network coverage and seamless roaming between different APs. The ESS includes multiple BSSs connected via the DS. Each BSS has its own AP, and the APs are connected to the DS. Server or Gateway : The server or gateway connects the DS to external networks, such as the Internet. It provides additional services such as authentication, DHCP, and network management.

52. MAC layers in IEEE 802.11 standard

53. Architecture of the IEEE 802.11 standard, Layers: Physical Layer : The part of Wi-Fi that actually sends data through the air. Data Link Layer : The part that makes sure data gets to where it needs to go without errors. LLC Sublayer : Keeps the communication organized and error-free. MAC Sublayer : Decides when each device gets to send data. DCF : Devices take turns sending data, waiting if someone else is sending. PCF : A central device (like a Wi-Fi router) decides who sends data and when.

54. Practical Uses of Wi-Fi Home Networks : Most homes use Wi-Fi to connect multiple devices to the Internet, such as smartphones, tablets, laptops, smart TVs, and gaming consoles. Public Hotspots : Many cafes, restaurants, airports, and other public places offer Wi-Fi for customers to stay connected. Business Networks : Businesses use Wi-Fi to provide employees and visitors with Internet access and to connect devices like printers and computers within the office. Benefits of Wi-Fi Convenience : No need for physical cables, allowing for flexible device placement and mobility. Multiple Devices : Can connect multiple devices simultaneously without the need for additional hardware. Easy Setup : Setting up a Wi-Fi network is generally straightforward and doesn’t require advanced technical knowledge.

55. Bluetooth Bluetooth is a wireless technology that allows devices to communicate with each other over short distances. It’s commonly used for connecting gadgets like headphones, speakers, keyboards, mice, and even transferring files between phones. How Bluetooth Works Short-Range Communication : Bluetooth operates in the 2.4 GHz frequency band and typically works within a range of about 10 meters (33 feet), although some devices can have a range up to 100 meters. Pairing Devices : Before devices can communicate, they need to be paired. Pairing involves making one device discoverable and then connecting to it from another device. This process usually requires a confirmation on both devices to ensure security. Data Transmission : Once paired, devices can exchange data, such as audio for wireless headphones, files between phones, or commands between a smartphone and a smart home device.

56. Piconet

57. A piconet is a type of wireless ad hoc network that consists of one primary device (often referred to as the master) and up to seven active secondary devices (slaves). Key Characteristics: Topology : A piconet uses a star topology, with the primary device at the center and secondary devices connected to it. Devices within a piconet can also form links with other piconets, creating a larger network known as a scatternet. Communication : The master device manages the communication between devices in the piconet, allocating time slots for data transmission. Only the master can communicate directly with all other devices; slaves can only communicate directly with the master, not with each other. Device Roles : Master : The central device that controls the communication within the piconet. Slave : Devices that are connected to the master and follow its communication schedule. Practical Example: In a typical Bluetooth piconet setup, a smartphone (master) may be connected to a Bluetooth headset, a smartwatch, and a car’s infotainment system (slaves), all of which communicate with the smartphone but not directly with each other.

58. Scatternet

59. Scatternet Multiple piconets connected together. Devices can be part of more than one piconet. These devices act as bridges, allowing communication between piconets. Example: Your smartphone connects to a Bluetooth headset (piconet 1) and also connects to a laptop (piconet 2). The smartphone bridges the two piconets, forming a scatternet. In your home, imagine this setup: Your smartphone connects to a smartwatch and a Bluetooth speaker. This is one small network called a piconet . Your smartphone also connects to a laptop. The laptop is connected to a printer and a mouse, forming another piconet. Your smartphone links these two piconets together, creating a bigger network called a scatternet .

60. Bluetooth layers

61. Bluetooth layers Radio Layer : The "wireless" part that sends and receives data as radio waves. Baseband Layer : The "middleman" that manages connections and data exchange. L2CAP Layer : The "postal service" that packages and sends data properly. Profiles : The "instructions" for specific Bluetooth tasks, like audio streaming or file transfers. Applications : The "apps" that perform tasks, such as playing music or transferring files. Audio : The "sound system" that handles Bluetooth audio. Control : The "remote control" that manages commands and settings for Bluetooth devices. Data : The "file transfer" part that handles general data transfers.

62. Practical Uses of Bluetooth Audio Devices : Connecting wireless headphones, earbuds, and speakers to phones, tablets, or computers. Peripheral Devices : Connecting keyboards, mice, and game controllers to computers and gaming consoles. File Transfer : Sending photos, videos, and documents between smartphones or from a phone to a computer. Smart Home Devices : Controlling smart lights, locks, and other home automation devices from a smartphone. Fitness and Health Devices : Syncing data from fitness trackers and smartwatches to health apps on a smartphone.