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