CPETECET 355

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CPET/ECET 355

• 2. Network Models
• Data Communications and Networking
• Fall 2004
• Professor Paul I-Hai Lin
• Electrical and Computer Engineering Technology
• Indiana University-Purdue University Fort Wayne
• www.ecet.ipfw.edu/lin

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2.1 Layered Tasks

• Sender, Receiver, and Carrier
• Hierarchy
• Preparation
• Sending
• Delivering
• Services
• Higher layer uses lower layer service

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2.2 Internet Model

• 5 Layer Model
• Layer 5 Application
• Layer 4 Transport
• Layer 3 Network
• Layer 2 Data Link
• Layer 1 Physical

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Peer-to-Peer Processes
From Figure 2.3 of Data Communications and
Networking by Forouzan, 3rd
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Interfaces between Layers

• Passing data and network info (down/up)
• Provide modularity to a network
• Isolate requiring changes to the surrounding
  layers

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Organization of the Layers

• Network Support Layers
• (physical aspects)
• Electrical specifications
• Physical connections
• Physical addressing
• Transport timing
• Reliability
• Layers
• Layer 1 Physical Layer
• Layer 2 Data Link Layer
• Layer 3 Network layer

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Organization of the Layers (cont.)

• Transport Layer (65536 ports)
• Layer 4
• TCP Transmission Control
• User Datagram Protocol
• User Support Layer
• Layer 5 Applications
• File Transport Protocol
• HTTP

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An Exchange Using Internet Model
From Figure 2.4 of Data Communications and
Networking by Forouzan, 3rd
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Physical Layer

• Data in the Bit Stream
• Data Rate
• Synchronization of Bits
• Interface Transmission Media
• Electrical Specification
• Mechanical Specification
• Functions and Procedures for data transmission

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Physical Layer
From Figure 2.5 of Data Communications and
Networking by Forouzan, 3rd
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Data Link Layer

• A Reliable Link
• Error free to the upper layer (network layer)
• Major Tasks
• Framing
• Physical addressing
• Flow control
• Error control
• Access control

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Data Link Layer (cont.)
From Figure 2.6 of Data Communications and
Networking by Forouzan, 3rd
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Data Link Layer Node-to-Node Delivery
From Figure 2.7 of Data Communications and
Networking by Forouzan, 3rd
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Example 2-1 Data frame

• Physical addresses
• Sender node physical address 10
• Receiver node Physical address 87
• Data
• Trailer extra bits for error detection

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Example 2-1 Data Frame (cont.)
From Figure 2.8 of Data Communications and
Networking by Forouzan, 3rd
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Network Layer

• Source to destination delivery of a data packet
  across multiple networks
• Upper layer - Transport layer
• Lower layer Data link layer
• Logical addressing (IP)
• Routing

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Network Layer
From Figure 2.9 of Data Communications and
Networking by Forouzan, 3rd
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Network Layer Source-to-Destination Delivery
From Figure 2.10 of Data Communications and
Networking by Forouzan, 3rd
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Example 2-2

• Sender (on one LAN)
• Network address A
• Physical address 10
• Receiver (on another LAN)
• Network address P
• Physical address 95
• Router

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Example 2-2
T2 Data A P 10 20
T2 Data A P 99 33
T2 Data A P 66 95
From Figure 2.11 of Data Communications and
Networking by Forouzan, 3rd
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Transport Layer

• Responsible for process-to-process delivery of
  the entire message
• Ensure reliable and orderly of data transporting
• Oversee error control and flow control

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Transport Layer (cont.)
From Figure 2.12 of Data Communications and
Networking by Forouzan, 3rd
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Transport Layer Major Tasks

• Port addressing (16-bit, 65536 ports)
• Message segmentation and reassembly
• Connection control
• Connection-oriented (TCP)
• Connection-less (User Datagram Protocol)
• Flow control
• Error Control

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Reliable Process-to-Process Delivery
From Figure 2.13 of Data Communications and
Networking by Forouzan, 3rd
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Example 2-3 Transport Layer Communication

• One message
• Chopped into two data packets
• The address of sending process is j
• The address of receiving process is k
• 2 data packets travel on different paths and may
  be out of order
• Reconstruct the message for layer 5

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Example 2-3 Transport Layer Communication (cont.)
From Figure 2.14 of Data Communications and
Networking by Forouzan, 3rd
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Application Layer

• Enable software of user to access the network
• Provide user interface and support of services
• Examples of services
• Email
• Remote log-in
• Remote file transfer and access
• WWW access, and more

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Application Layer (cont.)
From Figure 2.15 of Data Communications and
Networking by Forouzan, 3rd
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Summary of Duties
From Figure 2.16 of Data Communications and
Networking by Forouzan, 3rd
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2.3 OSI Model
From Figure 2.17 of Data Communications and
Networking by Forouzan, 3rd
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Summary
Questions?