LAN Protocols

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LAN Protocols

• Chapter 5

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Learning Objectives

• Explain the following LAN protocols and how they
  work with network operating systems IPX/SPX,
  NetBEUI, AppleTalk, TCP/IP, SNA, DLC, DNA
• Discuss and implement techniques to improve LAN
  performance

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How LAN Protocols Work with Network Operating
Systems

• Give meaning to simple electrical signal that are
  carried on network communications cables
• Can be transported individually or in
  combinations of two, three, or more

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Multiple LAN Protocols

• Advantage
• Network can perform many different functions on
  same LAN
• Disadvantage
• Some protocols operate in broadcast mode, causing
  a significant amount of redundant network traffic

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Properties of a LAN Protocol

• Reliable network links
• Relatively high speeds
• Source and destination node address handling
• Adherence to network standards (particularly IEEE
  802)

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LAN Protocols and Network Operating Systems
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IPX/SPX and Novell NetWare

• IPX (Internetwork Packet Exchange)
• Use with NetWare file server operating system
• Routable, but chatty
• SPX (Sequenced Packet Exchange)
• Enables exchange of application-specific data
  with greater reliability than IPX
• Often used for exchange of database data

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Deployment of IPX/SPX

• DOS-based computers
• DOS shell drivers created by NetWare
• Windows-based computers
• Novell Client32
• Open Datalink Interface (ODI)
• Network Driver Interface Specification (NDIS)
• Microsofts NetWare Link (NWLink)

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NDIS Network Architecture
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IPX/SPX and Novell NetWare

• Emulation of IPX/SPX
• Binding via NDIS

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Other Protocols Used with NetWare
continued
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Other Protocols Used with NetWare
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NetBEUI and Microsoft Windows Servers

• NetBEUI (NetBIOS Extended User Interface)
• Developed by IBM in mid-1980s
• Incorporates NetBIOS for communications across a
  network
• Native protocol for Windows NT Server
• Not routable most suited for small LANs using
  older Microsoft or IBM operating systems
• Corresponds with several layers of OSI model

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Why NetBEUI Works Well on Microsoft Networks

• Simple to install
• Handles large number of communication sessions on
  one network
• Low memory requirements can be quickly
  transported over small networks
• Solid error detection and recovery

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Disadvantages of NetBEUI

• Inability to route medium-sized and large
  networks not enough information in NetBEUI frame
  to identify specific networks
• Few network analysis tools

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AppleTalk and Mac OS

• AppleTalk
• Peer-to-peer protocol used on networks for
  communications between Macintosh computers
• Connectivity supported by Windows NT, Windows
  2000, Windows .NET, and NetWare Server

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AppleTalk Peer-to-Peer Networking
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Comparison of AppleTalk Phase I and Phase II
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Services of AppleTalk

• Remote access to network files via AppleShare
  File Server Application
• Printing services through AppleShare Print Server
  application
• File services to DOS- and Windows-based systems
  via AppleShare PC application

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Protocols Associated with AppleTalk

• AARP
• ADSP
• AFP
• ASP
• ATP
• DDP
• ELAP

• LLAP
• NBP
• PAP
• RTMP
• TLAP
• ZIP

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TCP/IP and Multiple Server Systems

• TCP/IP (Transmission Control Protocol/ Internet
  Protocol)
• Most widely used protocol
• Offers a suite of protocols
• Protocol of the Internet
• Supported by most network server and workstation
  operating systems

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Advantages of TCP/IP

• International language of network communications
• Designed for use with wide range of network
  devices
• Main protocol of most computer operating systems
• Many troubleshooting and network analysis tools
• Understood by a large body of network
  professionals

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continued
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Protocols and Applications of the TCP/IP Suite
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SNA and IBM Operating Systems

• SNA (Systems Network Architecture)
• Layered communications protocol used by IBM for
  communications between IBM mainframes and devices
• Uses token ring as the access method

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Advantages and Disadvantages of SNA

• Advantages
• Available for over 25 years
• Provide reliable and tested communications with
  IBM systems
• Disadvantage
• Proprietary requires special devices and complex
  training to configure, manage, and troubleshoot

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Physical Units on an SNA Network
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Protocols and Applications That Work Through SNA
continued
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DLC for Accessing IBM Operating Systems

• DLC (Data Link Control) protocol
• Emulates SNA on Microsoft Windows operating
  systems
• Not routable
• Not truly designed for peer-to-peer
  communications between workstations, but only for
  connectivity to older IBM mainframe

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DNA for Digital (Compaq) Computer Operating
Systems

• DNA (Digital Network Architecture)
• Developed for use on networks using DEC computers
• Advantage
• Closely follows OSI Reference model
• Disadvantages
• Proprietary implementation
• No longer widely used

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Improving LAN Performance

• Minimize number of LAN protocols that must cross
  each router
• Decreases the work routers must perform
• Enables routers to process traffic faster
• Does not create unnecessary traffic on network

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Which Protocol?

• Do packets need to be routed?
• Size of network?
• Types of servers in use and the protocols they
  use?
• Are there mainframe host computers what
  protocols do they use?
• Direct access to Internet or Web-based intranet
  applications?
• Speeds needed for WAN connections?
• Mission-critical applications?

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Improving LAN Performance

• Connectivity issues
• Eliminate unnecessary protocols configured on
  workstations

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Chapter Summary

• Commonly used LAN protocols and the network
  operating systems with which they are used
• Advantages and disadvantages of LAN protocols
• Improving LAN performance by using only the
  protocols necessary in a particular situation