1. A Small PC Network Chapter 6 Copyright 2001 Prentice Hall Revision 2: July 2001

2. 2 Small Peer-Peer PC Network n No dedicated (full-time) server – User PCs supply services – User PCs act as clients & servers n File Sharing – Each PC can make drives or directories available to other PCs – Can allow read-only or full access – Can require password for access n Printer Sharing – PC can make printers attached to it available to others

3. 3 Small Peer-Peer PC Network n Advantage – No dedicated server to purchase and maintain n Disadvantages – PC crashes or turned off, people using its files or printer are disconnected – Security often gives access to unauthorized people n Special problem if home network is connected to the Internet

4. 4 Elements of a Simple PC Network with a Dedicated Server Hub or Switch Server Client PC Server Wiring

5. 5 Elements of a Small PC Network n LAN Standards – We will focus on LANs that follow the Ethernet standard (80% do) n Small Ethernet PC networks use only UTP wiring n 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)

6. 6 Elements of a Small PC Network n Need a hub or switch to connect the PCs – Connector box with multiple plug-in jacks n Each PC needs a network interface card (NIC) – Implements physical & data link layer connection to the LAN n Wire – Business-grade UTP telephone wiring

7. 7 Elements of a Simple PC Network n Ethernet UTP Wiring – 4-pair bundle (8 wires) & RJ-45 connector – Pre-cut lengths (1 m, 2 m, 25 m, etc.) & connectors on both ends – Cut wire to lengths needed and attach connectors n Quality Level – Category 5 or Category 5e (enhanced) – Older categories (3 and 4) exist but are now fairly rare – New Category 6 is coming (not necessary for Ethernet) n Plenum Wiring – For Air conditioning ducts (no toxic fumes if burns)

8. 8 Elements of a Small PC Network n Ethernet Hub Operation (Broadcasting) – 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 – Operation is simple, hubs inexpensive Hub Bit

9. 9 Elements of a Small PC Network n 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) – Becomes a problem with 100+ PCs and 10 Mbps hub – Problem is intolerable with 200+ PCs with a 10 Mbps hub Must Wait

10. 10 Elements of a Small PC Network n Ethernet Switches – Station transmits frame to switch (data link layer operation) – Switch only transmits frame out port of destination PC – Multiple conversations can take place simultaneously because there is no broadcasting, which ties up all ports – No wait to transmit; no Latency; No shared speeds – More costly than hubs Switch Frame

11. 11 Elements of a Simple PC Network n 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

12. 12 Elements of a Simple PC Network n Servers – Provide services to client PCs – In peer-to-peer, PCs are clients & servers dedicated servers needed for more than 5 PCs – Most PC nets have multiple servers (1:10-50) – Require a NIC – Require a server operating system (SOS) – Require application software

13. 13 Elements of a Simple PC Network n Server Operating System (SOS) – Servers need operating systems more reliable than client PC operating systems – Often bundled with some application software – Windows NT/2000 Server, Novell NetWare, UNIX, LINUX n Application Software – Provides the services offered by the servers – E-mail, word processing, file sharing, etc. – Largest expense for PC Networks

14. 14 Elements of a Simple PC Network n Novell NetWare SOS – Once dominant, but market share has shrunk – Excellent file, print & directory service n UNIX ( Not for Small PC Networks) – Powerful workstation servers run UNIX – Extremely reliable & highly functional – Expensive & difficult to learn n Many versions of UNIX exist – Must retrain staff or hire UNIX staff

15. 15 Elements of a Small PC Network n LINUX ( Version of UNIX) – Runs on Intel PCs ( and compatibles) – Cost free or 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 – Requires Extensive Labor to Set Up, Maintain – Device driver software often is lacking – Requires more training because it is UNIX

16. 16 Elements of a Small PC Network n Microsoft Windows 2000 Server Operating System – Formerly Microsoft Windows NT Server – More robust than desktop Windows (Win 95, 98, 2000) – All 32-bit code – Easy to install, learn, and use (resembles desktop Windows) – Becoming dominant for small business and small department servers – Windows 2000 Server promise improved reliability & scalability

17. 17 Servers n Option: Put All Services on One Server – Cheapest for small organizations – SOS is multitasking; multiple applications is no problem n Option: One Application per Server – Can optimize hardware for application – More reliable, crashing service does not crash others – Security: users must log into appropriate server n Option: Hybrid – Some Servers Offering One Service, Others Offering Several – Distribute services in ways that make sense for the services, organization size, disk storage, processing speed.

18. 18 Servers n Cost (Difficult assessment) – Small organization: all services on single server – Larger organizations: optimization through multiple servers often minimizes costs n Typical Application Software – Word processing, e-mail, etc. – Must buy multi-user versions, not just a single copy from a retail store – License will limit the number of users – Will cost more than the SOS

19. 19 Server Application Software n File Service Allows File Sharing – File server stores program and data files n Shared file be accessed by any user with access rights n Built into most SOSs File Server Access Rights No Access Rights

20. 20 Server Application Software n Sharing application program files – Program is STORED on the file server not each PC – Greatly reduces installation labor – But program is EXECUTED on the client PC – Limited by power of client PCs, which do not get very large File Server

21. 21 Server Application Software n Print Service – Also built into SOSs – Print jobs go to shared printers – But they first go to the file server & 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 Client PC

22. 22 Server Application Software n Print Server – Print server feeds the print job to the printer – Simple and inexpensive (file server does work) – Low print server cost allows shared printers can be scattered throughout the office File Server Print Server

23. 23 Server Application Software n 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 – Parallel cable 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 UTP RJ-45 Port

24. 24 Server Application Software n Remote Access Service (RAS) – User dials into PC Network via modem – Server authenticates the user n User has equivalent access as local users n Lower response times due to telephone line speeds – Client PC needs RAS software LAN Internal Server RAS Dial-In Client Dial-Up Telephone Line RAS Client Software

25. 25 Internet Access for a Simple PC LAN n Serial Router – Simple, inexpensive router ($1,000 - 3,000) – One RJ-45 LAN port, one ISP Connection port – May provide security to stop outside hackers n Network address translation (NAT) hides addresses of internal machines n Only serial router’s IP address appears in outgoing packets n May provide firewall preventing unauthorized access Serial Router Access Line IP Packet with Serial Router’s IP Address

26. 26 Server Application Software n Directory Servers: S erver of resources spread among network – To use a resource, must know the server n Files must be accessed on particular servers – Directory server knows all resources on all servers n Can search for a specific file across servers – Directory server knows user access rights on all servers – Single login to directory server grants access to all other servers where user has access rights

27. 27 File Server Systems Administration n Set Access Rights for Each Directory, File – Ability to see directory or file – Ability to get read-only copy of a file in a directory – Ability to create, edit, & delete files & subdirectories – Ability to assign access rights to other users – Rights can be assigned to individuals or group n Using groups simplifies assignment of access rights – Assign individual to groups – Give access rights to groups – Members of groups then get those rights

28. 28 File Server Systems Administration n 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 ProcessingDatabase OracleQuickDB Assigned Browse And Read Rights

29. 29 File Server Systems Administration n Blocking of Inheritance – Assigning rights explicitly blocks inheritance – Only assigned rights are effective Application Word ProcessingDatabase Oracle (Browse and Execute Only) QuickDB Assigned Browse And Read Rights Assigned Browse And Execute Rights

30. 30 File Server Systems Administration n Omnibus Rights – Administrator normally has omnibus rights – Can read, delete, etc. any file in any directory – Serious security concern

31. 31 Setting Up a Client PC for Windows n Physically install a NIC n Set Up Microsoft Windows for Networking – Adapter (installed with NIC) – Protocol – Client

32. 32 Client PC Setup for Windows n 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, screw in place – Types of Slots n ISA for lower speeds n PCI for higher speeds (longer slot) n NIC must be compatible with slot Slot Mother Board NIC

33. 33 Client PC Setup for Windows n Install the NIC – Boot system after installation n Windows should recognize the new NIC n Setup: fairly automatic, may be asked for NIC disk n Some NICs have their own setup disks and should bypass automatic Windows setup. Check the NIC documentation