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Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
Network Fundamentals: Ch7 - Data Link Layer
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Network Fundamentals: Ch7 - Data Link Layer

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Data Link Layer Terms and Services such as frame, node, medium. …

Data Link Layer Terms and Services such as frame, node, medium.
Creating a frame.
Data Link Layer sublayers: Logical Link Control and Media Access Control.
Media Access control methods for both of shared and non-sahred media.
Physical Topology: is an arrangement of the nodes and the physical connections between them.
Logical Topology: is the way a network transfers frames from one node to the next.
Data link layer addressing requirements.
Ethernet Protocol for LANs, Point-to-Point Protocol for WANs and Wireless Protocol for LANs.

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  • 1. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Network Fundamentals Abdelkhalik Elsaid Mosa abdu.elsaid@yahoo.com http://abdelkhalik.staff.scuegypt.edu.eg/
  • 2. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Introduction • The Application layer provides the interface to the user. • The Transport layer is responsible for dividing and managing communications between the processes running in the two end systems. • The Network layer protocols organize our communication data so that it can travel across internetworks from source to destination  Packets do not have a way to directly access different media. • OSI Data Link layer prepares Network layer packets for transmission and controls access to the physical media. • The Data Link layer provides a means for exchanging data over a common local media, hop to hop delivery.
  • 3. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Data Link Layer terms and services • Frame: The Data Link layer PDU. • Node: The Layer 2 notation for a device on a network. • Media/medium (physical): The physical means for the transfer of information between two nodes. • Network (physical): Two or more nodes connected to a common medium, also called “Network segment”. • The Data Link layer performs two basic services: 1. Allows the upper layers to access the media using techniques such as Framing. 2. Controls how data is placed onto and received from the media using techniques such as Media Access Control and error detection.
  • 4. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Upper Layer Access to media
  • 5. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Creating a frame
  • 6. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Connecting upper layer services to media
  • 7. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Data Link Layer sublayers • Separating the Data Link layer into sublayers allows for one type of frame defined by the upper layer to access different types of media defined by the lower layer. IEEE 802.2 IEEE 802.3
  • 8. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Placing data on the media • Media Access Control “equivalent to traffic rules”: Regulating the placement of data frames onto the media. MAC techniques define if and how the nodes share the media. • The method of media access control used depends on 1. Media sharing: If and how the nodes share the media. 2. Topology: How the connection between the nodes appears to the Data Link layer.
  • 9. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Media Access control for shared media • Media access control methods for shared media: 1.Controlled “scheduled access or deterministic”: Each node has its own time to use the medium.
  • 10. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Media Access control for shared media • Media access control methods for shared media: 2. Contention-based ” non-deterministic”: All nodes compete for the use of the medium.
  • 11. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Media Access control for non-shared media • Media access control protocols for non-shared media require little or no control before placing frames onto the media.
  • 12. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Logical topology vs. physical topology • Physical Topology: is an arrangement of the nodes and the physical connections between them. • Logical Topology: is the way a network transfers frames from one node to the next.  The Data Link layer "sees" the logical topology of a network when controlling data access to the media.  The logical topology influences the type of network framing and media access control used. • Logical and physical topologies typically used in networks are 1. Point-to-Point 2. Multi-Access 3. Ring
  • 13. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Point to Point Topology • Point-to-Point topology: connects two nodes directly/ Indirectly together. • The media access control protocol can be very simple. • The end nodes communicating in a point-to-point network can be physically connected via a number of intermediate devices.
  • 14. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Multi-Access Topology • A logical multi-access topology enables a number of nodes to communicate by using the same shared media. • Data from only one node can be placed on the medium at any one time. • CSMA/CD or CSMA/CA Access Control methods can be used. • Token passing methods can also be used.
  • 15. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Ring Topology • In a logical ring topology, each node in turn receives a frame. If the frame is not addressed to the node, the node passes the frame to the next node. • Uses a controlled media access control called token passing.
  • 16. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Data Link Layer Protocols – The frame • There are many different Data Link layer protocols that describe Data Link layer frames.
  • 17. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Addressing Requirements • Data Link layer addressing depends on the logical topology.
  • 18. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Data Link Layer Protocols – The frame • The L2 protocol used depends on the logical topology of the network and the implementation of the Physical layer. • Ex: Ethernet , PPP, HDLC, Frame Relay, ATM. • The Layer 2 protocol used for a particular network topology is determined by the technology used to implement that topology. These technologies are 1. LAN Technology 2. WAN Technology • These technologies are determined by the size of the network, the number of hosts and the geographic scope, and the services to be provided over the network.
  • 19. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Ethernet Protocol for LANs • A family of networking technologies , IEEE 802.2 and 802.3. • Define both the Layer 2 protocols and the Layer 1 technologies. • Provides unacknowledged connectionless service over a shared media using CSMA/CD as the media access methods.
  • 20. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Point-to-Point Protocol for WANs • PPP is a protocol used to deliver frames between two nodes. • PPP standard is defined by RFCs.
  • 21. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Wireless Protocol for LANs • 802.11, Wi-Fi, is an extension of the IEEE 802 standards. It uses the same 802.2 LLC and 48-bit addressing scheme. • Contention-based system using CSMA/CA media access process. • uses Data Link acknowledgements to confirm that a frame is received successfully.
  • 22. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
  • 23. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Follow data through an Internetwork 1 2
  • 24. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Follow data through an Internetwork 3 4
  • 25. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Follow data through an Internetwork 5 6
  • 26. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Follow data through an Internetwork Data Link Layer of Router B gets data of the media7 8
  • 27. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Follow data through an Internetwork Data Link Layer of Router A gets data off the media Data Link Layer of Router B puts data on the media9 10
  • 28. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Follow data through an Internetwork Data Link Layer of Router A puts data on the media 11 12
  • 29. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Follow data through an Internetwork Physical Layer transports data across the media13 14
  • 30. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Follow data through an Internetwork 15 16
  • 31. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy Follow data through an Internetwork 17

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