Introduction to Management Information

Systems

Chapter 5 Data Communications

and Internet Technology

HTM 304

Fall 07

2

Content

1. 5-layer Architecture for Communication

2. Internet

3. Enterprise Network

4. Wireless

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Last Time: The 5-Layer Model

Hardware Layer: Set the devicesready for communication.

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Layer 3: Internet Layer

Runs the IP protocol

Data received from the above layers are divided into packets.

Key design issue – to determine how packets are routed from source to destination.

Routing: selecting paths – shorter route, avoiding heavy traffic, etc.

Router: special-purpose computing devices that process IP protocol – examine the destination IP addresses and decide where to send them.

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IP Address (IPv4)

Layer 3 handles IP address.

The Logical Addresses

Assigned when you get online, not permanently tied with the MAC address

Why? Don’t have to update every time a NIC is changed

An IP address is four bytes, totally 32 bits.

How many in total?

You can either specify your IP address (as most of the company’s server), or let the ISP assign one dynamically.

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IPv6

Windows Vista has adopted IPv6.

Totally 128 bits (=16 bytes) instead of 32 bits (=4 bytes)

How many total IPv6 addresses? 2128 3.4 * 1038 addresses

Approximately 5 * 1028 addresses * 6.5 billion people alive today.

Example of address: (8 Hexadecimal digits)

2001:0db8:85a3:08d3:1319:8a2e:0370:7334

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Exercise: Find your IP address

How to find your IP address?

“start” “run”: type “cmd” and click ok, the command prompt

window will pop up

Type command “ipconfig” to observe the report

Use “ping” command to check the connectivity between two

computers

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Router – 3rd Layer Equipment

Application Layer

Transport Layer

Internet Layer

Data Link Layer

Physical Layer

Computer A

Application Layer

Transport Layer

Internet Layer

Data Link Layer

Physical Layer

Internet Layer

Data Link Layer

Physical Layer

Computer B

Router A (can actually many)

Packets:Original IP – source IP + Data

Frames:Original MAC – Next MAC + Packets

Data Link Data Link

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Explain: Why Router? – handle address

Can be substituted by a computer with routingPrograms installed. Multiple NICs needed.

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Layer 4 Transport Layer

Handles transport protocol: TCP or UDP – software protocols

Application Layer

Transport Layer

Internet Layer

Data Link Layer

Physical Layer

Computer A

Application Layer

Transport Layer

Internet Layer

Data Link Layer

Physical Layer

Internet Layer

Data Link Layer

Physical Layer

Computer BRouter A (can actually many)

Data Link Data Link

Once paths from computer A to B is found, an end-to-end connection is established on the 4th layer. Meaning data can be transferred.

Point-to-point

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Layer 4 Protocols

TCP: Transmission Control Protocol

Receive data and transmission request from Layer 5 (application layer)

Send communication request to layer 3, layer 3 will then find one or more

route to the destination computer.

Destination computer send acknowledge back, indicating there is end-to-

end connection.

Break data from layer 5 into segments, and send each segments with

confirmation. (destination computer send acknowledge upon receiving

every segment)

UDP: User Datagram Protocol

Designed for short messages

Does almost everything the same as the TCP, except not requesting

confirmation.

Faster, more efficient for short messages and time-sensitive application

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Layer 5 The Application Layer

Layer 5 protocols for applications such as browsers, email, file

transfer, etc.

A standard email protocol

Simple Mail Transfer (SMTP)

Web page processing

Hypertext Transfer Protocol (HTTP)

File Transfer Protocol (FTP)

It governs how applications work with each other. (e.g. Firefox

v.s. IE 7)

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Review of the 5 layers

See your handout

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Review the Data Process

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Exercise

W

hich of the following is referred to as the

network cable?

Coaxial Cable

Fiber Optic Cable

Unshielded Twisted Pair

Twisted Pair Copper

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More exercise?

What is the name of data unit

transferred on the 2nd layer?

Packet

Bytes

Package

Frame

Segment

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Explain IEEE 802?

Which of the following standard in IEEE 802 is referred to

as Ethernet?

IEEE 802.11

IEEE 802.15

IEEE 802.3

IEEE 802.5

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Describe the three topologies mainly used to connect a LAN. Describe the pros and cons.

Which one can be extended to a large geographic area

Which topology corresponds to the Ethernet?

Describe the difference between an “end-to-end” connection and a “point-to-point” connection?

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Multiple Choices

__________ contains the destination computer’s IP

address in its header.

A frame

A segment

A packet

An email message