Content created and copyright Ó 1998-1999, by David L. Woodall, all Rights Reserved


Data Transmission Media

    1. UTP Cable Categories
      1. Category 1 - Traditional UTP telephone cable. Can transmit voice but not data
      2. Category 2 – UTP cable made of 4 twisted pairs, can transmit up to 4Mbps
      3. Category 3 – UTP cable made of 4 twisted pairs, each twisted 3 times per foot. Can transmit data up to 10Mbps
      4. Category 4 – UTP cable made of 4 twisted pairs. Can transmit data up to 16Mbps
      5. Category 5 – UTP cable made of 4 twisted pairs. Can transmit data up to 100Mbps
    2. Ethernet Cabling Types
      1. 10Base5 – Thicknet coax, a.k.a. RG-8. Carries signal up to 500 meters (1640 ft) at 50 ohms
      2. 10Base2 – Thinnet coax, a.k.a. RG-58. Carries signal up to 185 meters (607 ft) at 50 ohms
      3. 10BaseT – a.k.a. UTP Categories 3, 5, and 6?. MOST POPULAR of all Ethernet topologies. Carries signal up to 100 meters (330 ft) at 100Mbps
      4. 100BaseT – a.k.a. UTP Category 5 or 6. Carries signal up to 100 meters (330 ft) at 100Mbps (Category 5) or 155Mbps (Category 6)
    3. Token Ring Cabling Types
      1. Type 1 – STP – used to connect terminals and distribution panels
      2. Type 2 – STP – used to connect terminals located in the same physical area or room
      3. Type 3 – UTP – 4 twisted pairs, each twisted twice per foot (category 2?)
      4. Type 5 – Optical cable used only on the main ring path
      5. Type 6 – STP – does not carry signals as far as Type 1 or 2, used as patch cable or extensions in wiring closets.
      6. Type 8 – Used for runs under carpets
      7. Type 9 – Plenum rated, used for runs in ceilings
    4. Coax Cable Classifications
      1. CMS, CL2X – Restricted cable. Must be enclosed in conduit. Only allowed 10 ft of exposed cable
      2. CM, CL2 – General purpose. Used in areas other than risers or plenums
      3. CMR, CL2R – Riser Cable
      4. CMP, CL2P – Plenum Cable
      5. IEEE Project 802 Specifications

      6. 802.1 – Internetworking and Management
      7. 802.2 – Logical Link Control
      8. 802.3 – Carrier Sense with Multiple Access and Collision Detection (CSMA/CD or Ethernet)
      9. 802.4 – Token Bus LAN
      10. 802.5 – Token Ring LAN
      11. 802.6 – Metropolitan Area Network (MAN)
      12. 802.7 – Broadband Technical Advisory Group
      13. 802.8 – Fiber-Optic Technical Advisory Group
      14. 802.9 – Integrated Voice/Data Networks
      15. 802.10 – Network Security
      16. 802.11 – Wireless Network
      17. 802.12 – Demand Priority Access LAN, 100BaseVG-AnyLAN

Ethernet protocol implements a logical bus network that can transmit at 10 or 100Mbps. Every computer receives the information, but only the intended destination acknowledges the transmission.

Token Ring is a logical ring network that looks like a star network (because the ring is actually formed inside the hub). Token Ring devices can transmit at 4Mbps or 16Mbps.

FDDI (Fiber Distributed Data Interface) – Hubs are connected in a ring.

Hubs in a Token Ring are called MSAUs or MAUs (Multistation Access Units).


The OSI Reference Model (Open Systems Interconnection)

Developed by the ISO (International Standards Organization) in the early 1970s as a standard architecture for the development of computer networks. It provides a structured and consistent approach for describing, understanding, and implementing networks. The OSI Model:

The Layers and their Responsibilities

      1. 1. Application – Provides services that directly support user applications, such as the user interface, e-mail, file transfer, terminal emulation, database access, etc... Communicates through: Gateways and Application Interfaces
      2. 2. Presentation – Translates data between the formats the network requires and the computer expects. Handles character encoding, bit order, and byte order issues. Encodes and decodes data. Determines the format and structure of data. Compresses and decompresses, encrypts and decrypts data. Communicates through: Gateways and Application Interfaces
      3. 3. Session – Allows applications on a separate computer to share a connection (called a session). Establishes and maintains connection. Manages upper layer errors. Handles remote procedure calls. Synchronizes communicating nodes. Communicates through: Gateways and Application Interfaces
      4. 4. Transport – Ensures that packets are delivered error free, in sequence, and without loss or duplication. Takes action to correct faulty transmissions. Controls the flow of data. Acknowledges successful receipt of data. Fragments and reassembles data. Communicates through: Gateway Services, Routers, and Brouters
      5. 5. Network – Makes routing decisions and forwards packets (a.k.a. datagrams) for devices that could be farther away than a single link. Moves information to the correct address. Assembles and disassembles packets. Addresses and routes data packets. Determines best path for moving data through the network. Communicates through: Gateway Services, Routers, and Brouters
      6. 6. Data Link – Provides for the flow of data over a single link from one device to another. Controls access to communication channel. Controls flow of data. Organizes data into logical frames (logical units of information). Identifies the specific computer on the network. Detects errors. Communicates through: Switches, Bridges, Intelligent Hubs
      7. The Data Link Layer contains 2 sub-layers:
      8. A. The LLC (Logical Link Control) – The upper sub-layer which establishes and maintains links between communicating devices. Also responsible for frame error correction and hardware addresses.
      9. B. The MAC (Media Access Control) – The lower sub-layer which controls how devices share a media channel. (Either through contention or token passing)
      10. 7. Physical – Handles the sending and receiving of bits. Provides electrical and mechanical interfaces for a network. Specific type of medium used to connect network devices. Specifies how signals are transmitted on network. Communicates through: Repeaters, Hubs, Switches, Cables, Connectors, Transmitters, Receivers, Multiplexers
      11. Layers request the services of the layers below them and provide services to the layers above them. The point of communication between layers is called the SAP (Service Access Point).

        Each layer on the source computer communicates with the same layer on the destination computer by providing the receiving end with the information necessary to understand or verify the content of the transmitted data. Each layer on the source computer adds its’ own information (Header or Trailer) to the data. The headers and trailers are removed on the receiving end before the packet is passed to the next higher layer.

        Headers and Trailers typically contain the following information:

      12. Start Sequence – Indicates the beginning of a data unit and is typically used to synchronize when data movements occur
      13. Address – Both destination and source (as a return address)
      14. Hierarchical Addresses – Used on Internetworks. Includes a node address and a network address to identify computers on another network
      15. SAP Address – Identifies which application on a particular computer made the request
      16. Checksum and other Reliability Checks – Mathematical operations like Cyclic Redundancy Check (CRC) to verify integrity of data
      17. Content Descriptors – Information such as the sequence in which the messages were sent, the type of information contained in the message, or the length of the message
      18. Control Information – Additional information which might be necessary to control the transmission, for example, instructions for dealing with errors
      19. End Sequence – Indicates the end of the data unit
      20. Headers and Trailers create a "frame" around a message. For this reason the process of adding headers and trailers to a message is referred to as framing. Because each layer might add its’ own headers and trailers as the message passes through the network, it is sometimes necessary to distinguish which layer was the last to add a header or trailer. Often this is done by referring to the data unit (the combination of headers, message, and trailers) by a certain name. Any layer’s data units can be referred to as packets, but some layers’ data units do have specific names. They are:



Protocols are the rules by which computers communicate. Generally a "Network Protocol" defines how communications should begin and end properly, and the sequence of events that should occur during data transmissions. At the transmitting computer the protocol is responsible for:

At the receiving computer the protocol is responsible for


Common Network Protocols

      1. TCP – Transmission Control Protocol
      2. IP – Internet Protocol (defines and routes datagrams)
      3. IPX/SPX – Internetwork Packet Exchange/Sequenced Packet Exchange – Routable protocols created by Novell for NetWare networks
      4. NetBEUI
      5. HTTP
      6. Connection – Oriented and Connectionless Communication

      7. Connection-oriented methods guarantee delivery but are slower than connectionless. (TCP, SPX, X.25 {A WAN protocol})
      8. Connectionless do not guarantee delivery and are therefor faster. (IP, UDP {Part of IP Suite}, IPX, ATP, DDP)
      9. Application Protocols – (Run at Application Layer of OSI)

      10. APPC – Advanced Program to Program Communication – used mostly on AS/400 computers. IBM’s peer to peer SNA protocol
      11. FTAM – File Transfer Access and Management – File access protocol from the OSI architecture
      12. X.400 and X.500 – Email transmission and format protocols
      13. SMTP – Simple Mail Transfer Protocol – Email transfer protocol for the internet
      14. FTP – File Transfer Protocol for the internet
      15. SNMP – Simple Network Management Protocol – Monitors networks and networking programs created for the internet
      16. Telnet – A protocol for logging on to remote computers and processing shared data locally created on the internet
      17. NFS – Network File System – File sharing protocol for Unix networks
      18. NCP – NetWare Core Protocol – provides interface for file storage and retrieval services between workstations and the server

        Transport Protocols – (Run at Transport layer of OSI)

      20. TCP – Responsible for guaranteeing delivery of data packets in sequence
      21. SPX – Responsible for guaranteeing delivery of data packets in sequence
      22. NWLink – Responsible for guaranteeing delivery of data packets in sequence
      23. NetBIOS – Responsible for establishing the communication session
      24. NetBEUI – Responsible for providing data transport services
      25. NBP – Name Binding Protocol
      26. UDP – User Datagram Protocol
      27. DNS – Domain Name SERVICE
      28. Network Protocols (Run at Network layer of OSI)

      29. IP – Responsible for packet forwarding and routing
      30. IPX – Responsible for packet forwarding and routing
      31. NWLink – Responsible for packet forwarding and routing
      32. NetBEUI – Provides data transport services for NetBIOS communication sessions
      33. DDP – Datagram Delivery Protocol – Provides data transport services for the AppleTalk suite ( between Macs)
      34. ARP – Address Resolution Protocol – maps IP addresses (network) to data-link addresses (hardware)
      35. ATP - AppleTalk Transaction Protocol - Responsible for establishing the communication session and providing transport services in the Apple computer
      36. TCP/IP Protocols

      37. IP
      38. ARP – Address Resolution Protocol
      39. RIP – Routing Information Protocol – A routing protocol that performs route discovery by using hop counts (the number of routers a message must pass through to reach its destination)
      40. OSPF – Open Shortest Path First – A routing protocol that performs route discovery by using calculations based on bandwidth (not hops)
      41. TCP
      42. UDP
      43. FTP
      44. SMTP
      45. NFS – Network File System – A traditional file sharing protocol designed for use in Unix networks
      46. IPX/SPX Protocols

      47. IPX
      48. SPX
      49. NCP – Netware Core Protocol – provides interface for file storage and retrieval services between workstations and the server
      50. AppleTalk Protocols

      51. AppleShare – A file and print sharing protocol
      52. AFP – AppleTalk Filing Protocol – A protocol that provides sharing between Macs and DOS-based computers, provides an interface for communication between AppleTalk and other NOSs, and is responsible for file-system security
      53. DDP – Datagram Delivery Protocol – A connectionless protocol that runs at the Network layer and provides datagram services between Macs
      54. ATP – AppleTalk Transfer Protocol – A connectionless protocol that runs at the Transport layer and provides reliable transmissions, using acknowledgements
      55. Components of a Packet:

      56. 1. Header – Includes:
      1. 2. Data – The data component of the packet is the actual data being sent
      2. 3. Trailer – Exact trailer contents depend on the protocol. Typically, the trailer includes a CRC. If the CRC returns an unequal sum, the destination computer signals the source to re-send the packet.
      3. Routable Protocols have the ability to send data from one LAN to another.

        Protocol Suites are sets of different protocols that are typically used together. The NOS determines which protocol suites are available. NT provides NetBEUI, IPX/SPX, and TCP/IP.


        Common Protocol Suites

      4. Internet – a.k.a. TCP/IP. Actually includes hundreds of protocols but referred to as TCP/IP (Transmission Control Protocol/Internet Protocol). Perhaps the most widely accepted and versatile suite today. Has ability to connect dissimilar computers.
      5. OSI - Open Systems Interconnection. Designed to enable different computers to share data. Should be used when compatibility with OSI networks needs to be ensured.
      6. NetBEUI – NetBIOS Extended User Interface. Provided with all MS networking products. Small, fast, efficient, and compatible with all MS based networks. NetBIOS is routable, however, NetBEUI is not. NetBEUI cannot be used to communicate with non-MS based networks. Two advantages of NetBEUI are its’ small stack size and quick data-transfer rate.
      7. IPX/SPX – Internet Packet Exchange/Sequenced Packet Exchange. Used typically for client/server environments. SPX is similar to TCP, IPX is similar to IP. Early versions of IPX/SPX required separate NICs for every protocol suite used by a computer. As a result, the Open Data-link Interface (ODI) was developed, enabling a single NIC to support multiple protocols.
      8. Apple Talk – network architecture offering a set of layered protocols that are OSI model compliant. Provides some assurance that Macs will be able to communicate with any IBM-PC network.
      9. Types of WAN Connections

      10. X.25 - Operates at Network Layer. Channel addressing, virtual circuit packet switching with flow and error control. First WAN standard for packet switching. Assumes that LAPB (Link Access Procedures-Balanced) protocol is being used. Slower than other WAN connection services because of flow control and error-checking techniques it uses. Supports transmission speeds of up to 64Kbps
      11. ISDN - (Integrated Services Digital Network) Operates at the Physical and Data-Link Layers. Standard for voice, video, and data on existing public digital telephone network. Uses TDM (Time Division Multiplexing). Two most common types are:
      12. BRI (Basic Rate ISDN) - (also called 2B+D) Consists of 2 data channels at 64KB each and one management channel at 16KB. BRI has speeds up to 128Kbps

        PRI (Primary Rate ISDN) - Uses the entire bandwidth of a T1 (23 channels with the 24th as the D channel (management). PRI has speeds up to 1.544 Mbps

      13. Frame Relay - Operates at the Physical and LLC Layers. An upgrade to X.25, uses the higher layer protocols to provide error control. Because Frame Relay assumes a lower error rate, it transfers data at higher rates than X.25. Speeds of 56Kbps to 1.544Mbps
      14. ATM (Asynchronous Transfer Mode) - Operates at Network and LLC Layers. Uses fixed length, 53 byte cells (instead of packets) with a 5-byte header to transfer at VERY HIGH SPEEDS. Can be used for voice, data, fax, real-time video, CD-quality audio, and imaging. Asynchronous means that time slots don't occur periodically, as with TDM. Instead they are served on a first come basis. Same size cells allow for very high efficiency. Most common speeds are 155 and 622Mbps but can achieve speeds of up to 2Gbps.
      15. T1 - Point to point connection across 24 channels. Each channel is 64Kbps. Maximum speed of 1.544Mbps
      16. T3 - Point to point connections across 28 T1 lines with a speed of 44.736Mbps
      17. Switched 56 - A dial-up service, used on demand, and LEASED from the PSTN. Provides more bandwidth than regular analog modems. Speed of 56Kbps
      18. SONET (Synchronous Optical Network) - A high-speed fiber optic system. Can be used as a carrier service for WAN connection services such as ATM and ISDN. Speeds of greater than 1Gbps
      19. Considerations when choosing an Administrative Plan:

      20. Resources - that can be shared
      21. Network Shares - What you have chosen to share
      22. Permissions - The security assigned to a particular resource, either share level with read only or full access, or through Access Permissions, with rights granted to users or groups through an ACL
      23. Users
      24. Groups - The accounts that simplify user and security administration
      25. Rights - The abilities given to users or groups to manage or use different resources
      26. Client Operating Systems

      27. For Microsoft Clients to communicate with Windows NT, you must load the Client for Microsoft Networks
      28. For the clients to communicate with a Windows NT Workstation or Server computer, you can use TCP/IP, NetBEUI, or IPX
      29. NetWare servers do not use domains or workgroups, so you do not need to configure the clients to log onto a domain. However you do need to set the server name that the client will log in to. This is done through the client software, either Client for NetWare Networks, or the Novell Client 32 (provided by Novell). The Novell Client works better if you are using Novell IntranetWare.) Clients that want to communicate with the Novell NetWare Servers must run IPX, which is named NWLink on MS Windows devices
      30. Default Group Accounts

      31. By default the following 6 LOCAL Groups are created by NT and cannot be deleted:
      32. Administrators
      33. Power Users - Have normal user rights and permissions
      34. Users - Have Guest rights and permissions
      35. Guests - Can share directories and printers
      36. Backup Operators - Can bypass security to backup and restore files
      37. Replicator - This group supports file replication in a network domain
      38. Security Management

      39. The three types of security available on Windows NT are:
      40. Access Permissions - Simple password-protected shares. Allows for 2 password, one for read-only and one for full
      41. User-level Security - controls security by adding user or group permissions to resources
      42. File-level - available only on NTFS partitions, enables administrators to assign rights to files and folders, including restricting access or allowing limited access
      43. Windows 95 Security

      44. Read-Only
      45. Full
      46. Depends on Password
      47. In order to use user-level security on a Win95 share, you must have either a WinNT or NetWare server installed to authenticate and manage the users

        You can grant the following privileges to each user or group to access a Win95 share:

      48. Read-Only
      49. Full Access
      50. Custom - R, W ,Create, List, Change Attributes, and Change Permissions
      51. RAID Levels (Redundant Array of Inexpensive Disks

      52. Level 0 - Striping, in 64K Blocks, across 2-32 disks. Dramatically improves R and W performance, but loss of any drive loses all data.
      53. Level 1 - Mirroring. Duplexing is a variation of mirroring and requires an extra disk drive controller card. Need 2 drives to implement either. RAID Level 1 is the only fault-tolerance solution you can use to protect your boot disk
      54. Level 2 - Striping with error correction. Spreads data bit by bit across 2 or more drives. Error correction code is built from the bits and stored on an additional, separate drive (3 total).
      55. Level 3 - Striping with parity on a single drive. Spreads data byte by Byte across multiple drives. Parity information stored on a separate drive. Requires at least 3, and usually no more than 5 disks. Provides both performance and fault-tolerance enhancements
      56. Level 4 - Striping by block with parity on a single drive. Spreads data block by block (groups of 1-16 characters). Parity information is stored on a separate drive. Requires at least 3, and usually no more than 5 disks. As with Level 3, if a single drive fails, data can be rebuilt from the remaining drives and the parity drive
      57. Level 5 - Striping with parity across multiple drives. Operates in much the same manner as level 3. However parity data is spread across drives. Because parity is stored across the drives, more than 1 R and W can occur simultaneously. Requires at least 3, and as many as 32 disks. System and Boot drives cannot be part of a stripe set. They must be stored on a separate partition.
      58. WinNT supports RAID Levels 0, 1, and 5. NetWare supports Level 2 only.



        Installing and Configuring NICs and Multiple Network Adapters

      59. NIC - Hardware which requires software (the driver) to run it. Has hardware (MAC) address burned into PROM (Programmable Read Only Memory) on the card. MAC address is 6 bytes long, first 3 from IEEE, last 3 from manufacturer. NICs may store card information in the base memory address area of the system's memory.
      60. NICs - Coordinate the digital signaling between the PC and the cable and are responsible for the following:

Multi-Homing (or Multiple NIC) Techniques:

      1. WinNT is capable of handling multiple NICs in the same system at the same time. This can be very beneficial by allowing you to:
      2. Segment the Network - by allowing a WinNT server with multiple NICs to function as a router
      3. Putting a Workstation into Different Networks - by installing a second NIC in a NT Workstation, your computer could be in 2 networks simultaneously
      4. Data Bus Architecture

      5. ISA - Original IBM AT Bus architecture. Originally 8 bits, expanded to 16 bits in 1984. Was the first standard until the introduction of EISA
      6. EISA - 32 bit architecture. Both ISA and EISA cards work in these slots
      7. MicroChannel - Created by IBM as a replacement for ISA, introduced in PS2 computers. Runs as either 16 or 32 bit bus but is INCOMPATIBLE with ISA
      8. PCI - 32 bit local bus used widely today (both PC and Macintosh). Provides PnP functionality. Most PCI cards use 10BaseT or 100BaseT ONLY
      9. Network Adapter Installation

      10. When not using PnP, or if NT does not detect your NIC, follow these steps:

Hardware Conflicts

IRQs are hardware lines over which devices such as I/O ports, keyboards, disk drives, and NICs can send messages or interrupts to the CPU.

Assigned IRQs and their typical functions:

      1. 0 - Timer
      2. 1 - Keyboard
      3. 2 - Hardwired to IRQ 9
      4. 3 - COM2 and COM4
      5. 4 - COM1 and COM3
      6. 5 - LPT2 or MIDI
      7. 6 - Floppy Disk Controller
      8. 7 - LPT1
      9. 8 - System Clock
      10. 9 - Linked to IRQ2 or Sound Card
      11. 10 - Free, NIC, or Primary SCSI adapter
      12. 11 - Free, or Secondary SCSI adapter
      13. 12 - PS/2, Logitech, or bus mouse
      14. 13 - Math Processor
      15. 14 - Primary IDE hard disk controller
      16. 15 - Free or additional IDE controller
      17. Implementing a NetBIOS Naming Scheme

        NetBIOS is the INTERFACE that is used in WinNT, Win95, and OS/2. It allows applications to interface with lower-layer protocols.

        NetBIOS names must be unique, and no more than 15 characters. They are NOT case sensitive.

      18. UNC - Net use g:\\sales-mrkt\sales\resource
      19. Tools for Finding Errors

      20. Event Log
      21. Network Monitor - Frame-Level analysis, check packet types and errors
      22. Protocol (or Network) Analyzer - Packet-Level analysis, can capture and decode packets flowing through the server
      23. TCP/IP Troubleshooting Tools

      24. Ping - Packet Internet Groper) - does an echo send and receive to an IP address to see if it is alive
      25. Tracert - Traces a route from a source to a destination. Shows actual path through an internetwork
      26. Nbstat - Checks the NetBIOS table statistics to see which WinNT NetBios name has been resolved to an IP address
      27. NSLookup - Checks the DNS database for name resolution
      28. ARP - Resolves IP addresses to hardware addresses associated with the NICs
      29. Route - Allows you to add, view or delete route entries
      30. Event Log Viewer Main Log Areas

      31. System - Includes errors and warnings that describe system events
      32. Security - Keeps track of events turned on through WinNT auditing
      33. Application - Specific messages from applications

Event Log tracks the following Event Types:

Tools for Troubleshooting Cable Problems

      1. Digital Voltmeter (DVM) - Checks ohmage of cables and terminators and finds a short or open in the cabling (short=0, Open=too high or infinite)
      2. Time-Domain Reflectometer (TDR) - Finds a break, short, or imperfection in a cable. Also finds loss of decibels in fiber-optic Cable. Sends sound or light waves down a copper or fiber-optic cable
      3. Oscilloscope - Tests the digital signal in COAX. Measures fluctuations in signal voltage
      4. Advanced Cable Tester - Checks for the presence of a signal. Works up to the Transport Layer. Can test physical cable, as well as frame counts, collisions, congestion, and beaconing

Items to Check When Troubleshooting Cable Problems

Performance Monitor

      1. Items to watch when troubleshooting Server:
      2. Bytes Total/Sec
      3. Sessions Errored Out
      4. When Troubleshooting NetBEUI, NWLink, or IPX:
      5. Session Timeouts
      6. Failures Link
      7. Resource Local
      8. When Troubleshooting Network Performance:
      9. Session Timed Out
      10. Sessions Errored Out
      11. Jobs Queued
      12. Server Response Time



Content created and copyright Ó 1998-1999, by David L. Woodall, all Rights Reserved