LAN Protocols Chapter 5

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

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

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

Properties of a LAN Protocol Reliable network links Relatively high speeds Source and destination node address handling Adherence to network standards (particularly IEEE 802)

LAN Protocols and Network Operating Systems

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

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) Microsoft’s NetWare Link (NWLink)

NDIS Network Architecture

IPX/SPX and Novell NetWare Emulation of IPX/SPX Binding via NDIS

Other Protocols Used with NetWare continued…

Other Protocols Used with NetWare

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

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

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

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

AppleTalk Peer-to-Peer Networking

Comparison of AppleTalk Phase I and Phase II Phase 1Phase II No internetworking; allows only one zone Permits internetworking; up to 255 zones Maximum number of stations: 254 Maximum number of stations: several million Addressing accomplished by providing a node ID Addressing uses combination of node ID and network identification Functions only on a network in which it is the sole protocol Can work on a network that uses multiple protocols

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

Protocols Associated with AppleTalk AARP ADSP AFP ASP ATP DDP ELAP LLAP NBP PAP RTMP TLAP ZIP

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

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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Protocols and Applications of the TCP/IP Suite

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

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

Physical Units on an SNA Network

Protocols and Applications That Work Through SNA continued…

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

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

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

Improving LAN Performance Connectivity issues Eliminate unnecessary protocols configured on workstations

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?

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