220 likes | 469 Views
Rivier College CS575: Advanced LANs Chapter 6: Logical Link Control. IEEE 802 Protocol Layers Compared to OSI Model. Logical Link Control Services. Unacknowledged connectionless service Connection-mode service Acknowledged connectionless service. Logical Link Control (LLC) Primitives.
E N D
Rivier CollegeCS575: Advanced LANsChapter 6: Logical Link Control Logical Link Control
IEEE 802 Protocol Layers Compared to OSI Model Logical Link Control
Logical Link Control Services • Unacknowledged connectionless service • Connection-mode service • Acknowledged connectionless service Logical Link Control
Logical Link Control (LLC) Primitives Logical Link Control
Logical Link Control (LLC) Primitives Logical Link Control
Three LLC Protocols(referred to as types of operation) • Type 1 operation supports unacknowledged connectionless service • Type 2 operation supports connection-mode service • Type 3 operation supports acknowledged connectionless service Logical Link Control
LLC Classes available for a single station Logical Link Control
LLC Protocol Data Unit Formats Logical Link Control
LLC Protocol Data Units Logical Link Control
Examples of High-Level Data Link Control(HDLC) Operation Logical Link Control
Examples of High-Level Data Link Control(HDLC) Operation Logical Link Control
Service Primitive Types Logical Link Control
Time Sequence Diagrams for Service Primitives Logical Link Control
Flow Control: Model of Frame Transmission Logical Link Control
Stop-and-Wait Flow Control: Link Utilization Logical Link Control
Sliding-Window Flow Control Process Logical Link Control
Example of a Sliding-Window Protocol * Error-detection technique requires an Error-Detecting Code (e.g., CRC) Logical Link Control
Error Control Mechanisms * Error-detection technique requires an Error-Detecting Code (e.g., CRC) • Two Types of Possible Errors: • Lost PDU • Damaged PDU (some of the bits have been altered during transmission) • Methods of Error Control: • Error detection (the receiver detects errors and discards PDUs) • Positive acknowledgement is sent confirming error-free PDUs received • Retransmission after timeout • Negative acknowledgement and retransmission • Automatic Repeat Request (ARQ) turns an unreliable data link into a reliable one. Logical Link Control
Stop-and-Wait Automatic Repeat Request (ARQ) Logical Link Control
Go-Back-N Automatic Repeat Request (ARQ) Logical Link Control