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Chapter 1

  • Network – H/W & S/W

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  • Ex. Communicate 2 friend by postal mail

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Straight cable (568B 🡨 🡪568B)

Cross Cable (568A 🡨 🡪568B)

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Chapter 1

  • Network – H/W & S/W
  • Layered task
  • Ex. Communicate 2 friend by postal mail
  • 1 Higher Layer
  • 2 Middle Layer
  • 3 Lower Layer

Carrier for transmission

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Chapter 1� Network Model

  • The OSI model

standard for data communication.

  • The TCP/IP Model

protocol suite – commercial Architecture

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Figure 3-1

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OSI Model

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Figure 3-2

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OSI Layers

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Figure 3-3

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An Exchange Using the OSI Model

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Figure 3-4

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Layer 1. Physical Layer

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Layer 1. Physical Layer

  • Carry a bit stream over physical channel
  • Physical- devices e.g. NIC

transmission media- cable.

  • Bit pattern - (0001101)

must be transmitted- electrical/ optical signal

  • Clock synchronization.
  • Line configuration
  • Physical Topology
  • Transmission mode

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Figure 3-5

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Layer 2. Data Link Layer

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Figure 3-6

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Data Link Layer Example

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Layer 2. Data link Layer

  • Framing- stream , group of bits.
  • Physical Addressing
  • Flow control
  • Error control
  • Access control
  • node to node delivery.

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Figure 3-7

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Layer 3. Network Layer

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Figure 3-8

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Network Layer Example

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Figure 3-8-continued

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Network Layer Example

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Layer 3. Network layer

(End to End packet delivery)

  • The Network Layer Performs

network routing functions

responsible for S to D delivery of packets

fragmentation and reassembly

  • Routing- define route

- independent n/w connection create large n/w

  • Logical Addressing

Sender’s Address – Receiver’s Address

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Figure 3-9

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Layer 4. Transport Layer

Process to process delivery of message

-Message arrive in order

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Figure 3-10

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Transport Layer Example

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Figure 3-10-continued

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Transport Layer Example

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Layer 4. Transport Layer

  • The Transport Layer provides transparent transfer of data between end users, providing reliable data transfer services to the upper layers.
  • The Transport Layer controls the reliability of a given link through flow control, segmentation/desegmentation, and error control.

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Layer 4. Transport Layer

  • Service Point Addressing (PORT)
  • Several programs at same time

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process Process

A ------------- B

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  • Segmentation & reassembly

-Transmittable segments, Seq no.

  • Connection Control services.

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Figure 3-11

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Layer 5. Session Layer

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Layer 5: Session Layer

  • The Session Layer controls the dialogues (connections) between computers.
  • It establishes, manages and terminates the connections between the local and remote application.
  • It provides for full-duplex, half-duplex, or simplex operation, and establishes checkpointing

(e.g. file of 2000 pages & chk point of 100 pages.),

  • termination, and restart procedures. 

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Figure 3-12

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Layer 6. Presentation Layer

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Layer 6: Presentation Layer

  • Different Syntax & semantic information
  • Translation

-encoding

sender dependent format

common format

receiver dependent format

-encryption. –carry sensitive info.

-compression.- reduce the nr. of bits.

(e.g. multimedia, text, audio, video)

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Figure 3-13

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Layer 7. Application Layer

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Layer 7: Application Layer

  • Provide Services

- E-mail

- Remote file access / Transfer

- Shared database management

  • Application

-X.400 message handling service.

-X.500 directory service.

-FTAM

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Figure 3-14

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Summary of Layer Functions