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Chapter 6
 

Chapter 6

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    Chapter 6 Chapter 6 Presentation Transcript

    • A Small PC Network Chapter 6 Copyright 2001 Prentice Hall Revision 2: July 2001
    • Small Peer-Peer PC Network
      • No dedicated (full-time) server
      • User PCs supply services to each other
      • So user PCs act both as clients and as servers
    • Small Peer-Peer PC Network
      • File Sharing
        • Each PC can make certain disk drives or directories available to to other user PCs
        • Can allow others read-only or full access to files there
        • Can require password for access
    • Small Peer-Peer PC Network
      • Printer Sharing
        • Each PC can make one or more printers attached to it available to others
    • Small Peer-Peer PC Network
      • Advantage
        • No dedicated server to purchase and maintain
    • Small Peer-Peer PC Network
      • Disadvantages
        • If someone turns off their PC or crashes it, people using its files or printer are cut out
    • Small Peer-Peer PC Network
      • Disadvantages
        • Users often set up security poorly giving access to unauthorized people
        • Special problem if home network is connected to the Internet
      New
    • Small Peer-Peer PC Network
      • Overall
        • Beyond about 2-5 users, problems become too pronounced
        • Beyond about 10 users, very bad idea
      New
    • Elements of a Simple PC Network with a Dedicated Server Hub or Switch Server Client PC Client PC Server Wiring
    • Elements of a Small PC Network
      • LAN Standards
        • We will focus on LANs that follow the Ethernet standard (80% do)
      • Small Ethernet PC networks use only inexpensive UTP wiring
      • Speeds for NICs and Hubs or Switches
        • 10Base-T (10 Mbps, baseband, UTP)
        • 100Base-TX (100 Mbps, baseband, UTP)
        • 1000Base-T (Gigabit Ethernet) (1 Gbps)
    • Elements of a Small PC Network
      • Need a hub or switch to connect the PCs
        • Connector box with multiple plug-in jacks
        • Hubs and switches are described later
      • Each PC needs a network interface card (NIC)
        • Implements physical and data link layer connection to the LAN
      • Wire
        • Business-grade UTP telephone wiring
    • Elements of a Simple PC Network
      • Ethernet UTP Wiring
        • 4-pair bundle (8 wires)
        • Each pair is twisted
        • Terminates in RJ-45 connector
      • Quality Level
        • Category 5 or Category 5e (enhanced)
        • Older categories (3 and 4) exist but are now fairly rare
        • New Category 6 is coming but will not be necessary for Ethernet
      New
    • Elements of a Simple PC Network
      • Ethernet UTP Wiring
        • Come pre-cut in many useful lengths (1 m, 2 m, 25 m, etc.) with connectors already added to both ends
        • Can also cut wire to precise lengths needed and then attach connectors
          • Must test the wire after cutting it and attaching connectors!
    • Elements of a Simple PC Network
      • Plenum Wiring
        • For wiring run through airways; covering does not give off toxic fumes if it burns
          • Required if wires are run through air conditioning ducts
          • Needed in false ceilings and false floors
        • More expensive but required by law and concern for employee safety
    • Elements of a Small PC Network
      • Ethernet Hub Operation
        • One station transmits a single bit to a hub (physical layer operation)
        • Hub broadcasts bit to all attached stations
        • All but the destination PC should ignore the message
      Hub Hub Bit Bit
    • Elements of a Small PC Network
      • Ethernet Hubs
        • Broadcasting is simple, so
        • Hubs are inexpensive
    • Elements of a Small PC Network
      • Ethernet Hubs Can Create Latency
        • Only one station may transmit at a time or the signals will collide and be unreadable
        • Other stations must wait (latency)
      Must Wait
    • Elements of a Small PC Network
      • Ethernet Hubs Can Create Latency
        • Becomes a problem with 100+ PCs and 10 Mbps hub
        • 200 PCs is upper limit for tolerable service with a 10 Mbps hub
      Must Wait
    • Elements of a Small PC Network
      • Ethernet Switches
        • One station transmits a frame to a switch (data link layer operation)
        • Switch only transmits frame out port of destination PC
        • No broadcasting out all ports
      Switch Switch Frame Frame
    • Elements of a Small PC Network
      • Ethernet Switches
        • Multiple conversations can take place simultaneously because there is no broadcasting, which ties up all ports
        • No wait to transmit; no Latency
      Switch
    • Elements of a Simple PC Network
      • Client PCs
        • End user’s desktop or notebook PC
        • Add network interface card (NIC)
        • With Win95, Win98, Win ME, Win NT, or Win 2000 Professional, Win XP, and Macintosh, no extra software is needed
        • Networks have many client PCs
    • Elements of a Simple PC Network
      • Servers
        • Provide services to client PCs
        • Usually PCs themselves
        • Most PC nets have multiple servers
        • Require a NIC
        • Require a server operating system (SOS)
        • Require application software
    • Elements of a Simple PC Network
      • Server Operating System (SOS)
        • Servers need operating systems more reliable than client PC operating systems
        • Windows NT/2000 Server, Novell NetWare, UNIX, LINUX
      • Application Software
        • Provides the services offered by the servers
        • E-mail, word processing, file sharing, etc.
        • More expensive than the SOS
    • Elements of a Simple PC Network
      • Novell NetWare SOS
        • Once dominant, but market share has shrunk
        • Excellent file and print service
        • Excellent directory service (later)
        • Until recently, was not sufficiently robust and scalable for servers other than file servers
    • Elements of a Small PC Network
      • Microsoft Windows Server Operating System
        • More robust than desktop Windows (Win 95, Win 98, Win 2000 Professional, etc.)
        • All 32-bit code
        • Microsoft Windows NT Server before 2000
        • Newer Microsoft Windows 2000 Server
          • Versions in order of increasing functionality: Windows 2000 Server, Advanced Server, DataCenter Server
      New
    • Elements of a Small PC Network
      • Microsoft Windows Server Operating System
        • Easy to install, learn, and use because resembles desktop Windows
        • Becoming dominant for small business and small department servers
        • Windows NT Server has had serious reliability and scalability problems
        • Windows 2000 Server versions promise to improve reliability and scalability
    • Elements of a Small PC Network
      • UNIX
        • Powerful workstation servers run UNIX
        • Extremely reliable
        • Workstation servers running UNIX dominate the enterprise server market
    • Elements of a Small PC Network
      • UNIX
        • Expensive to buy
        • Must retrain staff or hire UNIX staff
        • Many versions of UNIX exist
          • Most run the same application software
          • However, have different management utilities, etc., requiring training for each version used
        • Not for Small PC Networks
    • Elements of a Small PC Network
      • LINUX
        • Version of UNIX
        • Runs on Intel PCs ( and compatibles); low cost
        • Available free
          • But usually pay around $50 to $150 for packaged version
        • Reliable like other UNIX versions
        • Open Source : Many people are developing tools to add to the LINUX core
    • Elements of a Small PC Network
      • LINUX
        • Available in Distributions
          • A distribution has the LINUX kernel plus other programs
          • Available on CD-ROM or by downloading
          • Distributions from different LINUX vendors differ in the specific programs included
          • Differences make selection, implementation difficult
      New
    • Elements of a Small PC Network
      • LINUX
        • Requires Extensive Labor to Set Up, Maintain
        • Device driver software often is lacking for printers, disk drives, and other devices
        • Requires more training because it is UNIX
        • Better distributions and support coming?
      New
    • Servers
      • Options
        • Put all services on one server, or
        • One server per service, or
        • In-Between solutions
    • Servers
      • Option: Put All Services on One Server
        • Cheapest for small organizations
    • Servers
      • Option: One Service Application per Server
        • Can optimize hardware for application
        • More reliable, because a crashing service does not crash others
        • Security: users cannot log into one service, switch to another easily
    • Servers
      • Option: Hybrid with Some Servers Offering One Service, Others Offering Several
        • Distribute services in ways that make sense for the services, organization size, etc.
    • Servers
      • Cost (Which is Cheapest?)
        • Difficult to know
        • For small organization, most or all services on one usually is cheapest
        • For larger organizations, optimization through multiple servers often minimizes costs
    • Server Application Software
      • File Service Allows File Sharing
        • File server stores program and data files
        • Shared file be accessed by any user with access rights
        • Built into most SOSs
      File Server Access Rights No Access Rights
    • Server Application Software
      • File Service
        • For sharing application program files also
        • No need to install applications on each PC
          • Greatly reduces installation labor
      File Server
    • Server Application Software
      • File Server Program Access
        • Program is STORED on the file server
      File Server
    • Server Application Software
      • File Server Program Access
        • But program is EXECUTED on the client PC
        • Limited by power of client PCs, which do not get very large
      File Server
    • Server Application Software
      • Print Service
        • Also built into SOSs
        • Print jobs go to shared printers
        • But they first go to the file server
        • Not directly to the print server!
      File Server Print Server Shared Printer Client PC
    • Server Application Software
      • Print Service
        • File server stores print job in a print queue until print server is ready to print it
        • File server sends the print job to the print server
      File Server Print Server Shared Printer
    • Server Application Software
      • Print Server
        • Print server feeds the print job to the printer
        • Print servers are simple and inexpensive because the file server does most of the work
        • Low print server cost allows shared printers can be scattered throughout the office
      File Server Print Server
    • Server Application Software
      • Print Server
        • Connects to printer via parallel port on the print server; no special printer needed
        • Has NIC to connect to the hub or switch
        • Requires an RJ-45 port on the hub or switch
      Print Server Parallel Cable UTP RJ-45 Port
    • Server Application Software
      • Print Server Location
        • Parallel cable distance limitation requires print server to be within 1-2 meters of the printer
        • UTP allows print server to be up to 100 meters from the hub or switch
      Print Server Parallel Cable (1-2 m only) UTP (up to 100 m) RJ-45 Port New
    • Server Application Software
      • Typical Application Software
        • Word processing, e-mail, etc.
        • Must buy multiuser versions, not just a single copy from a retail store
        • License will limit the number of users
        • Will cost more than the SOS
      New New
    • Server Application Software
      • Remote Access Service (RAS)
        • User dials into a remote access server
        • Server authenticates the user (user must prove identity)
        • If authenticated, user may use internal servers
        • Client PC needs RAS software
      LAN Internal Server RAS Dial-In Client Dial-Up Telephone Line RAS Client Software
    • Server Application Software
      • Internet Access for a Simple PC LAN
        • Serial Router
        • Simple, inexpensive router
        • One RJ-45 port for LAN, one suitable port for ISP Connection
      Serial Router Access Line
    • Server Application Software
      • Serial Routers
        • May provide security to stop outside hackers
          • Network address translation (NAT) hides addresses of internal machines
          • Only serial router’s IP address appears in outgoing packets
      Serial Router Access Line IP Packet with Serial Router’s IP Address
    • Server Application Software
      • Serial Routers
        • Provide security to stop outside hackers
          • May provide a firewall (discussed in Chapter 10) to prevent unauthorized access from Internet hackers
      Serial Router Access Line
    • Server Application Software
      • Directory Servers
        • Problem: Most networks have many servers
        • To use a resource, must know the server
          • To send e-mail, address is user@server
          • Files must be accessed on particular servers
    • Server Application Software
      • Directory Servers
        • Directory server knows all resources on all servers
        • Can send mail to user (without @server)
        • Can search for a specific file across servers
      Directory Server
    • Server Application Software
      • Directory Servers
        • Know user access rights on all servers
        • Single login to directory server
        • After that, get access to all other servers where user has access rights
      Directory Server Single Login
    • File Server Systems Administration
      • Set Access Rights for Each Directory, File
        • The ability to even see a directory or file (otherwise, it will be invisible)
        • The ability to get a read-only copy of a file in a directory (a copy that cannot be edited and then saved under the same name)
        • The ability to create, edit, and delete files and subdirectories
        • The ability to assign access rights in a directory to other users
    • File Server Systems Administration
      • Set Up Access Rights for Each Directory, File
        • Must be done for each individual in each directory!
        • Usually, however, assign individual to groups
        • Give access rights to groups
        • Members of groups then get those rights
        • Using groups greatly simplifies the assignment of access rights
    • File Server Systems Administration
      • Automatic Inheritance of Access Rights
        • Assign rights to individual or group in a directory
        • Rights automatically inherited in lower directories
        • Simplifies rights assignment
      Application Word Processing Database Oracle QuickDB Assigned Browse And Read Rights Inherits Browse And Read Rights Inherits Browse And Read Rights
    • File Server Systems Administration
      • Blocking of Inheritance
        • If assign rights explicitly in subdirectory, inheritance is blocked
        • Only assigned rights are effective
      Application Word Processing Database Oracle ( Browse and Execute Only ) QuickDB Assigned Browse And Read Rights Inherit Browse And Read Rights Assigned Browse And Execute Rights
    • File Server Systems Administration
      • The Assignment of Rights: Recap
        • Rights can be assigned to individuals or group
          • Group members receive all rights assigned to the group
        • Rights are automatically inherited in lower-level directories, unless
        • Rights are explicitly assigned in a directory, in which case automatic inheritance is blocked and only explicitly assigned rights are in effect in that directory
    • File Server Systems Administration
      • Omnibus Rights
        • Administrator normally has omnibus rights
        • Can read, delete, etc. any file in any directory
        • Serious security concern
    • Setting Up a Client PC for Windows
      • Physically install a NIC
      • Set Up Microsoft Windows for Networking
        • Adapter (installed with NIC)
        • Protocol
        • Client
    • Client PC Setup for Windows
      • Install NIC
        • Physically open systems unit
        • Main printed circuit board is the mother board
        • Has slots for expansion boards
        • Press NIC expansion board into slot, use screw to hold in place
      Slot Mother Board NIC
    • Client PC Setup for Windows
      • Install NIC
        • Types of Slots
        • ISA for up lower speeds
        • PCI for higher speeds (longer slot)
        • NIC must be compatible with slot
      Slot Mother Board NIC
    • Client PC Setup for Windows
      • Install the NIC
        • Boot system after installation
        • Windows should recognize the new NIC
        • Setup will be fairly automatic, although you may be asked to provide a disk that came with the NIC
        • Some NICs have their own setup disks and should bypass automatic Windows setup. Check the NIC documentation
    • Client PC Setup for Windows
      • Set Up Microsoft Networking
      • In Windows 95 and Windows 98,
        • Go to the Start Button
        • Choose Settings
        • Choose Control Panel
        • Double click the Network icon
        • This opens the Network Dialog Box
    • Client PC Setup for Windows
      • Be sure the Configuration tab is selected in the Network Dialog Box
        • You will see adapters, protocols, clients, and services that have already been added
      • Operations
        • Add : To add an adapter, protocol, client, or service
        • Remove : To remove one
        • Properties : To see or change the properties of the selected adapter, protocol, client, or service
    • Client PC Setup for Microsoft Windows
      • Adding a Protocol
        • In the Network Dialog Box, clicking the “Add” button takes you to the Select Network Component Type dialog box
        • Choose Protocol , then hit Add
        • You then go to the Select Network Protocol dialog box
        • Choose the Manufacturer and Protocol your server requires
    • Client PC Setup for Microsoft Windows
      • Configuring a Protocol
        • In the Network Dialog Box, click on the protocol you installed
        • Click the Properties button takes you to the properties dialog box for that protocol
        • Set up the properties
        • Bind the protocol to your client and adapter
    • Client PC Setup for Microsoft Windows
      • Client
        • In the Network Dialog Box, clicking the “Add” button takes you to the Select Network Component Type dialog box
        • Choose Client , then hit Add
        • You then go to the Select Network Client dialog box
        • Choose the manufacturer and client your server requires
    • Setting Up a Peer-to-Peer Network
      • For Each PC
        • Install the Client for Microsoft Networks
        • This supports peer-peer networking
      • Implement Sharing
        • In the Network Dialog Box,
        • Click the File and Print Sharing button
        • Enable file and print sharing by clicking on the appropriate boxes
      New
    • Setting Up a Peer-Peer Network
      • To Share a Specific Printer
        • Choose Start , Settings , Printers
        • Right click on icon for printer to be shared
        • Choose Sharing in the pop-up menu
        • Select Shared As in the Properties Dialog Box and give the printer any name
        • Give a password if desired
        • Anyone can now use it if they have the password or if you set no password
      New
    • Setting Up a Peer-Peer Network
      • To share a disk or directory’s files
        • In Explorer or My Computer , right click on disk or directory to be shared
        • Select Sharing in the pop-up menu
      • In (name of item selected) Sharing Dialog Box
        • Click Shared As radio button
          • Give shared name (how others will refer to it)
          • Add a comment if desired
      New
    • Setting Up a Peer-Peer Network
      • In (name of items selected) Sharing Dialog Box
        • Select an Access Type Radio Button
          • Read-Only
            • Anyone can read but cannot change
            • Can give password
          • Full (can do anything)
            • Can do anything
            • Can give password
          • Depends on Password
            • Can give different passwords for read-only, full
      New
    • Using a Shared Resource
      • Using a Shared printer
        • In application, choose Print
        • Select printer as usual
        • May need to give password
      • Using a Shared File or Directory
        • Choose Network Neighborhood
        • Select the desired file or directory
        • May need to give password
      New