Introduction to Networking

1
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Overview
Lesson 2
Lesson 3
Lesson 4

• To better understand the client/server network,
  it is important to take a look back at how
  networks worked before client/servers existed.
• The mainframe/terminal network was the
  predominant network architecture prior to the
  client/server.

Lesson 5
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2
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Overview
Lesson 2
Lesson 3
Lesson 4

• Many aspects of the mainframe/terminal
  environment can be found in the client/server
  including
• Centralized access to large amounts of
  information
• Centralized system management
• Efficiency of cost with smaller systems for large
  user groups

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3
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Overview
Lesson 2
Lesson 3
Lesson 4

• As computing power increased for small-scale
  computers, most user groups could be served by a
  personal computer (PC)-size machine and received
  comparable services provided by mainframes at a
  fraction of the cost.
• The client or desktop PC costperformance ratio
  allowed the client machine to do a considerable
  amount of its own processing and storage.
• Progression in computer technology has led to the
  majority of local area network (LAN)-based
  networks.

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4
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Lessons
Lesson 2
Lesson 3
Lesson 4

• 1) Example of LAN Technology Ethernet
• 2) Peer-to-Peer Networking
• 3) Network Operating Systems
• 4) Client/Server Networks
• 5) Information Flow Between Clientand Server

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5
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Example of LAN Technology
Ethernet
Lesson 2
Lesson 3
Lesson 4

• It is estimated that over 75 percent of all local
  networks contain Ethernet technology.
• Ethernet is a Data Link and Physical Layer
  specification.

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6
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Example of LAN Technology
Ethernet
Lesson 2
Lesson 3
Lesson 4

• At the end of this lesson you should be able to
  demonstrate
• An understanding of Ethernet media access and
  operation
• An understanding of common Ethernet configurations

Objectives
Lesson 5
Summary
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Terms
Key Point

• Ethernet frames are broad-cast to all nodes on
  a bus.

7
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Example of LAN Technology
Ethernet
Lesson 2
Lesson 3
Lesson 4

• Ethernet technology is now the primary technology
  used in LANs.
• Ethernet has 10 megabits per second (Mbps), 100
  Mbps, and 1 gigabit per second (Gbps) throughput,
  and uses the CSMA/CD method to access the
  physical media.
• Standard Ethernet equipment is very inexpensive.
• The majority of LANs use twisted pair cabling for
  connectivity between the computer, NIC, and
  connectivity device.

Ethernet Operation
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8
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Example of LAN Technology
Ethernet
Lesson 2
Lesson 3
Lesson 4

• The inventors of Ethernet chose CSMA/CD as their
  technique for controlling access to the medium
  (the bus).
• An Ethernet node must have the ability to listen
  to the bus and transmit at the same time. To
  transmit a frame, the following logic is
  followed.
• 1) Listen to the bus to determine whether any
  other node is transmitting.
• 2) When no signal is detected, start transmitting
  the frame.

Ethernet Media Access
Lesson 5
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9
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Example of LAN Technology
Ethernet
Lesson 2
Lesson 3
Lesson 4

• 3) While transmitting, also listen to the bus.
  Compare the received frame to what was
  transmitted. As long as they are the same,
  continue transmitting.
• 4) If what is received is not what was
  transmitted, assume a collision. Stop
  transmitting.
• 5) Warn all other stations that a collision has
  been detected by sending a special electrical
  sequence.
• 6) Wait a random time and then start over with
  step 1.

Ethernet Media Access (cont.)
Lesson 5
Summary
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10
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Example of LAN Technology
Ethernet
Lesson 2
Lesson 3
Lesson 4

• An important aspect of the CSMA/CD algorithm is
  the random-length interval (a few milliseconds)
  that a node waits before trying to retransmit
  when a collision occurs.
• On a heavily used network, collisions will occur,
  and some time will be lost each time this
  happens.
• A node stops transmitting as soon as a collision
  is detected this is the significance of the CD
  in CSMA/CD.

Ethernet Media Access (cont.)
Lesson 5
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11
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Example of LAN Technology
Ethernet
Lesson 2
Lesson 3
Lesson 4

• The most straightforward Ethernet configuration
  consists of several Ethernet workstations
  daisy-chained together onto a single Ethernet
  segment.

Ethernet Configurations
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Terms
Simple EthernetConfiguration
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Example of LAN Technology
Ethernet
Lesson 2
Lesson 3
Lesson 4

• This is a star configuration and is found in
  Ethernet networks using 10BaseT technology. All
  nodes attached to the hub share the same 10 Mbps
  bandwidth.

Ethernet Configurations (cont.)
Lesson 5
Summary
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Ethernet HubConfiguration
13
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Example of LAN Technology
Ethernet
Lesson 2
Lesson 3
Lesson 4

• The next Ethernet configuration consists of two
  individual Ethernet segments connected by a
  bridge.

Ethernet Configurations (cont.)
Lesson 5
Summary
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Terms
Ethernet Hubsand Bridges
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Example of LAN Technology
Ethernet
Lesson 2
Lesson 3
Lesson 4

• Ethernet switches are high performance devices
  that allow multiple Ethernet segments and/or
  individual ports to connect, each at full
  Ethernet rates.
• Ethernet switches are also called switching hubs,
  and they provide network segmentation in a single
  box.

Ethernet Configurations (cont.)
Lesson 5
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15
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Example of LAN Technology
Ethernet
Lesson 2
Lesson 3
Lesson 4
Ethernet Configurations (cont.)
Lesson 5
Summary
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Terms
Ethernet Switch
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Example of LAN Technology
Ethernet
Lesson 2
Lesson 3
Lesson 4

• 1) Collisions are normal on CSMA/CD LANs and not
  usually the result of errors.True or False
• 2) The majority of 10-Mbps Ethernet LANs use
  fiber optic technology. True or False
• 3) Briefly describe the CSMA/CD Ethernet access
  method.

Activities
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Example of LAN Technology
Ethernet
Lesson 2
Lesson 3
Lesson 4

• 4) Draw an Ethernet network consisting of a
  single 12-port hub, 10 clients, and 2 servers.
• 5) An additional four clients must be added to
  the network. Draw another diagram showing how to
  add another 12-port hub to the network, and how
  the additional clients will be added.

Activities (cont.)
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18
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Example of LAN Technology
Ethernet
Lesson 2
Lesson 3
Lesson 4

• 1) Go to Charles Spurgeons Ethernet page at
  http//wwwhost.ots.utexas.edu/ethernet/. This is
  a good resource for general Ethernet information.
  
• 2) When was the original Ethernet design
  foreseen?
• 3 What is IEEE 802.3u?
• 4) What is IEEE 802.3z? Does this speed make
  sense to the desktop computer? Discuss.

Extended Activities
Lesson 5
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19
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Peer-to-Peer Networking
Lesson 2
Lesson 3
A peer-to-peer network is a network where nodes
attached to the network share the same
communication capabilities and are not controlled
by a specific device.
Lesson 4
Lesson 5
Summary
Quiz
Terms
Objectives

• At the end of this lesson you should be able to
  demonstrate an understanding of
• Typical traffic patternsin a peer-to-peer
  network
• How peer-to-peernetworks areconstructed

Key Point

• Communication can beinitiated by any node in a
  peer-to-peer network.

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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Peer-to-Peer Networking
Lesson 2
Lesson 3
Lesson 4
Network Traffic

• Network traffic refers to the combination of
  individual traffic patterns, or flows, in a
  network. These traffic patterns are based on two
  common methods of communication that take place
  between endpoints, namely
• Peer-to-peer
• Client/server

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21
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Peer-to-Peer Networking
Lesson 2
Lesson 3
Lesson 4

• Individual nodes attachedto a network
  communicatein one or multiple modes,depending
  on networkresources, nodes, andapplication
  capabilities.

Network Traffic (cont.)
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Peer-to-Peer Networking
Lesson 2
Lesson 3
Lesson 4

• Peer-to-Peer Traffic
• Peer-to-peer traffic is traffic typically seen
  between similar nodes (clients).
• The communicating nodes have similar application
  and communication capabilities.
• Each node in the network can communicate with any
  other node in the network. There is no obvious
  source or destination traffic pattern.

Network Traffic (cont.)
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Peer-to-Peer Networking
Lesson 2
Lesson 3
Lesson 4

• Peer-to-Peer Traffic

Network Traffic (cont.)
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Peer-to-Peer Networking
Lesson 2
Lesson 3
Lesson 4

• Construction of a Peer-to-peer Network (cont.)
• To understand how to construct and use a
  peer-to-peer network, let us look at a popular
  method used for building peer-to-peer networks. A
  peer-to-peer network can be built with the
  following three components
• NICs
• Cables and connectors
• Peer networking compatible operating system

Network Traffic (cont.)
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Peer-to-Peer Networking
Lesson 2
Lesson 3
Lesson 4

• Construction of a Peer-to-peer Network (cont.)
• The NIC and compatible driver are used to
  transmit information out of the computer and onto
  the network.
• Then connect the NICs with the cabling. The most
  widely used method is with Ethernet NICs and
  unshielded twisted pair (UTP) cabling.
• The NICs, and therefore devices, are attached
  using an Ethernet hub and UTP cabling.

Network Traffic (cont.)
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Peer-to-Peer Networking
Lesson 2
Lesson 3
Lesson 4

• Construction of a Peer-to-peer Network (cont.)
• Software is also required to generate the
  protocol headers for transferring information
  across the network.
• Most operating systems today contain the
  necessary software for building a peer-to-peer
  network.

Network Traffic (cont.)
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Peer-to-Peer Networking
Lesson 2
Lesson 3
Lesson 4
Activities

• Contrast the two patterns of network traffic
  peer-to-peer and client/server.

Lesson 5
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Peer-to-Peer Networking
Lesson 2
Lesson 3
Lesson 4
Extended Activities
Lesson 5
Summary

• 1) Discuss the practical aspects of the number of
  nodes a peer-to-peer network will support on a
  10Mbps Ethernet that shares files, printers, and
  Internet access.
• 2) Can a peer-to-peer network be constructed if
  two groups of peers are geographically separated?
  Explain.

Quiz
Terms
29
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Network Operating Systems
Lesson 2
Lesson 3
NOSs are specialized software packages used
tobuild client/server networks. Combined, a NOS
and computer hardware create the server
capability in a client/server network.
Lesson 4
Lesson 5
Summary
Quiz
Terms

• At the end of this lesson you shouldbe able to
• Understand the basic components of a NOS
• Name common NOSs used in todays networks

Objectives
Key Point

• NOSs provide client accessto shared resources.

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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Network Operating Systems
Lesson 2
Lesson 3
Lesson 4
Operating System Components

• LAN operating systems, or NOSs, can be divided
  into four components
• Server platform
• Network services software
• Network redirection software
• Communication software

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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Network Operating Systems
Lesson 2
Lesson 3
Lesson 4
Operating System Components (cont.)

• These components work together to support the
  distribution of network services to users.

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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Network Operating Systems
Lesson 2
Lesson 3
Lesson 4

• The server platform supports basic network
  operations, such as the network file system,
  memory management, and scheduling of tasks. The
  server platform should provide
• Preemptive multitasking
• Shared memory
• Protected memory

Operating System Components (cont.)
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Network Operating Systems
Lesson 2
Lesson 3
Lesson 4

• Network services software running on the server
  platform provides the user with services that
  range from basic to very complex.
• The network redirection software coexists with
  the operating system in the users workstation or
  PC.
• The communication software provides the protocols
  needed to transmit requests for services over the
  network.

Operating System Components (cont.)
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Network Operating Systems
Lesson 2
Lesson 3
Lesson 4

• The server should be capable of restricting
  access to applications and data using login IDs,
  or some other form of control.
• The functionality, reliability, and performance
  of NOSs can vary significantly because of
  architecture differences.

Operating System Components (cont.)
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35
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Network Operating Systems
Lesson 2
Lesson 3
Lesson 4

• Examples of common NOSs found in computer
  networks are
• 1) Novell NetWare
• 2) Microsoft NT
• 3) AppleTalk
• Novell NetWare and Microsoft NT are the most
  commonly used NOSs. AppleTalk is also common, but
  it primarily supports Macintosh computers and is
  not widely used in PC-based networks.

Example NOSs Used in Networks
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36
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Network Operating Systems
Lesson 2
Lesson 3
Lesson 4
1) A NOS on a server handles client requests.
List some functions that a server might perform
on behalf of clients. 2) Redirection software on
the client determines whether requests are being
made for local or remote system resources. True
or False 3) To be accessible, a server must be on
the same LAN as the client. True or False
Activities
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37
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Network Operating Systems
Lesson 2
Lesson 3
Lesson 4
4) If a client has been enabled to communicate
with a server, the client cannot participate in
peer-to-peer exchanges. True or False 5) If a
server is running a TCP/IP stack and a client is
running NetBEUI, can they communicate?
Explain. 6) A server uses logon IDs to control
client access. True or False 7) UNIX is also a
NOS. True or False
Activities
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38
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Network Operating Systems
Lesson 2
Lesson 3
Lesson 4
Extended Activities
1) Go to Web sites www.microsoft.com,
www.novell.com, and www.apple.com, and find
information on the functionality of their latest
NOS offerings. Discuss. 2) Using a Web search
engine resource, try to find out what the
installed customer base is for Windows NT and
Novell NetWare NOSs. 3) Can LINUX be used as a
NOS? Explain.
Lesson 5
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39
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Network Operating Systems
Lesson 2
Lesson 3
Lesson 4
Extended Activities
4) Where is the Banyan VINES NOS commonly
found? 5) If you were going to implement a NOS in
a 10-employee company, which NOS would you use
and why? What topology and wiring structure would
you use? Explain.
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40
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Client/Server Networks
Lesson 2
Lesson 3
The client/server model is the most widely used
networking architecture that exists today.
Lesson 4
Lesson 5
Summary
Quiz

• At the end of this lesson you should be able to
• Understand the role of the client in a
  client/server network
• Understand the role of the server in a
  client/server network

Objectives
Terms
Key Point

• Resource sharing is themost common reason to
  using a client/server network.

41
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Client/Server Networks
Lesson 2
Lesson 3
Lesson 4

• The client/server model divides a task into two
  parts, and executes each part on a different
  system on the network.

Client/Server
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Client/Server Networks
Lesson 2
Lesson 3
Lesson 4

• The client and server processes interact with
  each other by transmitting request/reply pairs.
• The client process initiates an interaction by
  issuing a request to the server.
• The server process responds with a reply
  satisfying the request.

Client/Server (cont.)
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Client/Server Networks
Lesson 2
Lesson 3
Lesson 4

• A client/server architecture has two primary
  advantages
• Distributed applicationApplications can be
  distributed on the network based on their
  requirements for resources.
• Resource sharingA server process typically can
  serve many clients, thus client/server
  architecture is a good way to implement resource
  sharing.

Client/Server (cont.)
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44
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Client/Server Networks
Lesson 2
Lesson 3
Lesson 4

• Examples of resources commonly shared through
  client/server arrangements are computing cycles,
  graphics capabilities, and databases.
• The client process is often found on an end-user
  node, such as a workstation or PC.
• The server process often runs on more powerful
  systems, such as a network file server.

Client/Server (cont.)
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45
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Client/Server Networks
Lesson 2
Lesson 3
Lesson 4
Activities

• Using the diagram, describe all the steps
  necessary to produce a printed report for one of
  the clients. Number the steps in their proper
  sequence.
• These are the parameters
• a. The client does not have the application on
  its hard drive. It is on an application server.
• b. The file server is also functioning as an
  application server.
• c. There are three files required to generate
  the report, two are on the server and one is on
  the client.
• d. Other clients are also printing reports.

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46
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Client/Server Networks
Lesson 2
Lesson 3
Lesson 4

• Discuss the following questions in focus groups
• 1) Why does it sometimes make sense to put
  servers in with departmental workstations
  (workgroups), instead of on a corporate backbone?
  
• 2) When would it make sense to use a peer-to-peer
  NOS instead of a full-blown client/server NOS?
  When does it make more sense to use a full-blown
  client/server NOS instead of a peer-to-peer NOS?

Extended Activities
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47
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3
Lesson 4

• The purpose of this lesson is to show how
  protocols are used for transferring a file
  between a client and server.
• There are many different protocol stacks that
  have been implemented for performing basic
  operations using a network.

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48
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3
Lesson 4

• At the end of this lesson you should be able to
• Understand the basics of information flow between
  client and server
• Understand the format of information as itflows
  between client and server

Objectives
Lesson 5
Summary
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Key Point

• Processes generateprotocol headers used tomove
  informationbetween applications.

49
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3
Lesson 4
Information Flow and Format

• Six diagrams are presented that illustrate the
  programs, processes, and protocols required for
  sending information from a client to a server
  attached to the same physical network. The
  following protocols are used
• Server Message Block (SMB)
• NetBIOS
• TCP
• IP
• Ethernet

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50
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3
Lesson 4

• The File Open Request from Client Diagram
  demonstrates the SMB/NetBIOS/TCP/IP/Ethernet
  protocol stack located inside the client and
  server computers.

Information Flow and Format (cont.)
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3
Lesson 4

• The application program interfaces to the network
  through a series of processes, beginning with
  SMB.
• SMB on the client side initiates requests to the
  server SMB process for file operations.
• On the server side, the SMB process is
  responsible for opening, reading, and closing a
  file.

Information Flow and Format (cont.)
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3
Lesson 4

• The protocols underneath the SMB protocol are
  used for transmitting the SMB requests and
  responses back and forth across the network.
• The Ethernet header is responsible for
  transmitting the frame and frame contents to the
  correct NIC, which is located inside the server.

Information Flow and Format (cont.)
Lesson 5
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Key Point

• Request/Reply pairs areused in a
  client/servernetwork.

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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3
Lesson 4

• The application headers are built on the sending
  computer station and decapsulated by the
  corresponding process on the receiver.
• By the time the SMB request gets processed by the
  SMB software on the server, the other headers
  have been stripped off by the appropriate
  processes on the receiving node.

Information Flow and Format (cont.)
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3
Lesson 4

• The Open Reply from Server Diagram illustrates
  the response from the NT file server. The reply
  indicates that the file is on the server and has
  been opened by the server application.

Information Flow and Format (cont.)
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3
Lesson 4

• The frame is carrying the SMB response from the
  server. There will also be a difference in the
  destination addresses of the frame, packet, and
  message.
• The destination addresses will now indicate the
  NIC, IP process, and TCP process on the client
  because the response is going back to the client.
• This an Ethernet bus topology.

Information Flow and Format (cont.)
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3
Lesson 4

• With a bus, there are most likely many nodes
  attached to the bus. When several nodes share the
  same bus, each node will receive the frame
  transmitted between client and server, and vice
  versa.
• Only the node that has a NIC address that matches
  the address in the Ethernet frame header will
  process the information inside the frame.

Information Flow and Format (cont.)
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3
Lesson 4

• The IP process in the main CPU of the client
  machine will process the IP packet.
• If there is a match, the IP process will pass the
  contents of the packet (message), to the TCP
  process.
• Information will continue to move up the protocol
  stack until it arrives at the SMB process.
• The reply destination is SMB, which generated the
  initial file open request.

Information Flow and Format (cont.)
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3
Lesson 4

• The Client Read Request Diagram illustrates
  another step in the client/server information
  flow for this type of transaction.

Information Flow and Format (cont.)
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3
Lesson 4

• The same processes generate protocol headers for
  the read request.
• Each header is added as the request is moved down
  the protocol stack until the frame exits the
  Windows 95 client via the NIC.

Information Flow and Format (cont.)
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Introduction to Networking
Introduction
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Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3
Lesson 4

• The Server Read Reply Diagram illustrates the
  response from the server.

Information Flow and Format (cont.)
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Introduction to Networking
Introduction
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Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3
Lesson 4

• If a large file is sent back from the server to
  the client, it could take many packets and frames
  to move the information across the Ethernet
  network.
• The packets would have to be reassembled on the
  client by the Transport Layer before passing the
  file to the SMB process.
• Once the file has been sent to the client and
  stored on the client machine, the file must be
  closed.

Information Flow and Format (cont.)
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Introduction to Networking
Introduction
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Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3
Lesson 4

• This is done with a close request, sent from the
  client to the server. and is shown on the Client
  Close Request Diagram.

Information Flow and Format (cont.)
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Introduction to Networking
Introduction
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Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3
Lesson 4

• In a shared (networked) environment, a file must
  be closed so that other users can have access to
  the file.
• The final frame is from the server back to the
  client.

Information Flow and Format (cont.)
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3
Lesson 4

• The Server Close Reply Diagram illustrates that
  the file is closed and the transaction is
  complete.

Information Flow and Format (cont.)
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3
Lesson 4

• This completes the transaction between client and
  server.
• In a shared environment using many clients and a
  server, the server is responsible for tracking
  client progress and making sure each client task
  is processed in order of priority.

Information Flow and Format (cont.)
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66
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3

• Consider the following network
• 1) Briefly describe the following services shown
  in the above protocol stack

Lesson 4
Activities
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3

• 2) Using short lines with directional arrows,
  describe the information flow between the client
  and server for a complete file read operation
  (including open and close). The sequence is
  started for you.
• Client/server
• Client desires to read a file gt
• lt Server reads reply
• SMB open file request from server gt
• lt Client closes request
• Client read request gt
• lt Server close reply

Lesson 4
Activities (cont.)
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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Information Flow Between
Client and Server
Lesson 2
Lesson 3
Lesson 4
Extended Activities

• Break into six focus groups, one for each of the
  client/server file operation diagrams (adjust
  focus groups according to class size).
• 1) Each group will discuss and present among
  themselves what functions the various layers are
  performing on the client side and server side.
• 2) If the client and server are located on the
  same physical network, is TCP/IP required?
  Explain.

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69
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Summary
Lesson 2
Lesson 3
Lesson 4

• Ethernet comes in several speeds, the most
  predominant is 10 Mbps.
• Ethernet is also implemented at 100 Mbps and
  1,000 Mbps (1 Gbps).
• Ethernet networks are configured in a variety of
  ways, the most common is a star network using UTP
  cabling.

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70
Introduction to Networking
Introduction
Lesson 1
Local Area Networks Summary
Lesson 2
Lesson 3
Lesson 4

• Peer-to-peer communication is when the nodes
  attached to the network are basically equal, and
  any node can initiate communication with any
  other node on the network.
• With client/server networking, a server is
  present in the network for processing client
  requests.
• Information is typically generated by the client
  in the form of a request to the server.

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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Summary
Lesson 2
Lesson 3
Lesson 4

• The server responds with a reply to each specific
  request of the client.
• Protocol headers are generated by a client
  computer as information is moved from an
  application, through communication processes and
  across the bus to the NIC.
• Once at the NIC, a frame is generated that
  encapsulates the packet, message, and request
  which is sent across the communication channel.

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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Summary
Lesson 2
Lesson 3
Lesson 4

• At the receiving end, the protocol headers are
  used to transmit the request up through the
  protocol stacks to the receiving application.
• Headers are processed and removed (decapsulated)
  by the clients peer process on the receiving
  side.

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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Quiz
Lesson 2
Lesson 3
Lesson 4

• 1) Which of the following is not a LAN
  communication process?
• a. Peer to peer
• b. Client to server
• c. Client to peer
• 2) List the four components of NOS architecture.
• a. Server platform
• b. Network services software
• c. Network redirection software
• d. Communications software

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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Quiz
Lesson 2
Lesson 3
Lesson 4

• 3) Which of the following are primary functions
  of the server platform?
• a. Preemptive multitasking
• b. Shared memory
• c. Protected memory
• d. All of the above
• 4) Name at least three NOSs.
• a. Netware
• b. NT
• c. AppleShare
• 5) Name at least two differences between a
  peer-to-peer network and client/server network.

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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Terms
Lesson 2
Lesson 3
Lesson 4

• AppleTalk Filing Protocol (AFP)AFP is the
  protocol used in Apple Networks for retrieving
  and storing files across a network.
• Carrier Sense Multiple Access with Collision
  Detections (CSMA/CD)The inventors of Ethernet
  chose the CSMA/CD technique for controlling
  access to the medium.
• Network Operating System (NOS)NOS is the
  software that manages server operations and
  provides services to clients. The NOS manages the
  interface between the networks underlying
  transport capabilities and applications residing
  on the server.

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Introduction to Networking
Introduction
Lesson 1
Local Area Networks Terms
Lesson 2
Lesson 3
Lesson 4

• RedirectorA redirector is a client software
  component in a client/server configuration. It is
  normally used in reference to the Novell NetWare
  NOS. The redirector is responsible for deciding
  if a request for a computer service (i.e., read a
  file) is for the local computer or network
  server.
• TrafficTraffic refers to the combination of
  information flow going to and from devices
  attached to a network.

Lesson 5
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Terms