csc0056: data communication lecture 02: layered network ... · network layer •virtual...
TRANSCRIPT
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CSC0056: Data Communication
Lecture 02:Layered Network Architecture
Instructor: Chao Wang 王超
Department of Computer Science and Information Engineering
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Course information
• Instructor: Chao Wang 王超 (https://wangc86.github.io/ )• Email: [email protected]
• Office: Room 511, Applied Science Building, Gongguan Campus
• Office hours: Wednesdays and Fridays, 10am-noon, or by appointment
• Course website: https://wangc86.github.io/csc0056/• Homework submission: via NTNU Moodle (https://moodle.ntnu.edu.tw/ )
• Course meetings: Mondays 9:10-12:10 in C007, Gongguan Campus
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Acknowledgement: Some slides’ materials in this course are borrowed with permission fromthe 2014 edition of the course taught by Prof. Yao-Hua Ho 賀耀華Figures are obtained from the textbook available at http://web.mit.edu/dimitrib/www/datanets.html
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Layered system architecture
• Module: a device/process that perform a function
• Black-box view of modules
• Communication between modules• Protocol
• Interface
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Layered system architecture (cont.)
• Advantage • Simplicity of design
• Easy to understand
• Standard, interchangeable modules
• Disadvantage
(if too many layers)• Duplicated functionality
• Additional latency
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Modern example:AUTOSAR (Automotive Open System Architecture)
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https://autosar.org/fileadmin/user_upload/standards/classic/4-3/AUTOSAR_EXP_LayeredSoftwareArchitecture.pdf
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Modern example: Industrial IoT Systems
• Cloud + edges of a cloud
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Chao Wang, Christopher Gill, Chenyang Lu. FRAME: Fault Tolerant and Real-Time Messaging for Edge Computing.IEEE International Conference on Distributed Computing Systems (ICDCS), accepted, 2019.
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Data communication
• The OSI model• Seven layers
• In this course, we focus on layers beneath Session
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Transport layer
• Virtual end-to-end message service to the higher layers
• Functions• Break messages into packets (at the transmitting end)
• Reassemble packets into messages (at the receiving end)
• Re-sequence packets at destination
• Recover from residual errors and failures
• Provide end-to-end flow control
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Network layer
• Virtual host-to-host packet service to the higher layers
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• Each host (node) contains one network layer module
• Provide routing and flow control for the network
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Data link control layer
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• Virtual reliable point-to-point link for sending and receiving packet
• Functions• Framing – determine the start and end of packets
• Error detection – identify corrupted packets
• Error correction – correct or retransmit packets
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The MAC sublayer
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• MAC (Medium access control)
• Function• Allocate the multi-access channel
so that each node can successfully transmit its frames without undue interference from the other nodes
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Physical layer
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• Transmit and receive bits over a link
• Functions• Encoding – transform bits into signals• Filtering – reduce signal noises• Modulation – reduce noise, increase
transmission range, etc.
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Encapsulation of data
• What happen if there are too many layers?
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Take a break
• Wireless technology?
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Into the physical layer
• Linear time-invariant (LTI) systems:
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A physical channel(i.e., an LTI system)
Input signal s(t) Output signal r(t)
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Communication channel with filtering
• Signal distortion
• Intersymbol interference
(read the note of lecture02 at
https://wangc86.github.io/csc0056/lec2note.pdf )
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Summary of lecture 02
• Layered network architecture
• The physical layer: channels and modems• See the note at https://wangc86.github.io/csc0056/lec2note.pdf
• Next lecture: Error detection at the data link layer
• Course logistics• Remember to visit and view the course website (e.g., via this QR code)
• Submit your homework assignments and view scores via NTNU Moodle
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