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Full text of "3Com Etherseries Local Area Network"

SY, I I A 9394b-5002 



NAVAL POSTGRADUATE SCHOOL 

Monterey, California 





A4-N4 





3COM 


ETHERSERIES LOCAL 


AREA 


NETWORK 










by 














David L. Anders 


land 












March 1989 








The 


sis 


Ac 


Ivisor: Norman 


F. ! 


Bchneidewind 

















Approved for public release; distribution is unlimited 



T2416A6 



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val Postgraduate School 



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Naval Postgraduate School 



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?terey, California 93943-5000 



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Monterey, California 93943-5000 



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ITlE (include Security Claudication) 

3COM ETHERSERIES LOCAL AREA NETWORK 



ERSQNAL AUTHQH(S) _ . , _ 

\ndersland, David L 



TYPE OF REPORT 

ster's Thesis 



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14 Date O c REPORT (Year, Month, Day) 

1989, March 



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UPPLEMENTARY NOTATION 

ie views expressed in this thesis are those of the author and do not reflect the official 
>licy or position of the Department of Defense or the U.S. Government. 



COSATI CODES 



FIELD 



GROUP 



SUB-GRO'.'P 



18 SUBJECT TERMS {Continue on reverie if neceuary and identify by block number) 

Local Area. Networks ; Networks 



ABSTRACT (Continue on reverse if neceuary and identify by block number) 

The purpose of this thesis is to provide an overview of the requirements 
3 protocols required for the implementation of an Ethernet LAN. The 
pendix to this thesis is a User's Manual for the 3Com EtherSeries Network 
rsion 2.4. The manual is specifically written for use in the Administrative 
iences Department Information Systems lab at the Naval Postgraduate School. 



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Approved for public release; distribution is unlimited 

3COM EtherSeries Local Area Network 

by 

David L. Andersland 

Lieutenant, United States Naval Reserve 

B.S., University of Minnesota, 1981 



Submitted in partial fulfillment of the 
requirements for the degree of 



MASTER OF SCIENCE IN INFORMATION SYSTEMS 



from the 

NAVAL POSTGRADUATE SCHOOL 
March 1989 



ABSTRACT 

The purpose of this thesis is to provide an overview of 
the requirements and protocols required for the implementation 
of an Ethernet LAN. The appendix to this thesis is a User's 
Manual for the 3Com EtherSeries Network version 2.4. The 
manual is specifically written for use in the Administrative 
Sciences Department Information Systems lab at the Naval 
Postgraduate School. 



111 



CI 



TABLE OF CONTENTS 

I. BACKGROUND 1 

A. PURPOSE OF A LAN 1 

B. BASIC LAN IMPLEMENTATION CONSIDERATIONS 2 

II. ETHERNET LOCAL AREA NETWORKS 3 

A. HISTORY OF ETHERNET 3 

B. ETHERNET BASIC COMPONENTS 4 

C. ETHERNET THEORY OF OPERATION 8 

D. ETHERNET PERFORMANCE CHARACTERISTICS 11 

III. 3COM NETWORK 13 

IV. 3COM HARDWARE 14 

A. WORKSTATIONS 14 

B. ETHERLINK 14 

C. COAXIAL CABLE 14 

D. BNC T-ADAPTER 15 

E. TERMINATORS 15 

V. 3COM SOFTWARE 16 

A. ETHERSHARE 16 

B. ETHERPRINT 17 

C. ETHERMAIL 18 

D. ETHERMENU 18 

VI. CONCLUSIONS AND RECOMMENDATIONS 19 

A. LAN MANAGEMENT 19 

B. CONFIGURATION MANAGEMENT 19 

iv 



B SCHOOL 
M0 ' Y. CALIFORNIA 93943-500! 

C. OPERATIONS AND MAINTENANCE 19 

D. PERFORMANCE MONITORING 20 

E. SECURITY 20 

APPENDIX: 3COM ETHERSERIES LAN USER MANUAL 21 

LIST OF REFERENCES 52 

INITIAL DISTRIBUTION LIST 53 



I. BACKGROUND 

The Naval Postgraduate School has implemented a 3Com 
Etherseries baseband Ethernet Local Area Network (LAN) . The 
purpose of this thesis is to explore the requirements and 
protocols required in the implementation of an Ethernet LAN, 
discuss the demands of 3Com's Etherseries network as regards 
hardware and software, and develop a comprehensive student's 
user manual. 

A. PURPOSE OF A LAN 

The purpose of a LAN has evolved from just sharing 
expensive computer peripherals laser printers, hard disks, and 
software to reduce costs. Robert Metcalfe, a co-inventor of 
Ethernet, subscribes to the new view that the purpose of LAN's 
is to share information creating "workgroup information 
systems." [Ref. l:p. 9] 

The design of a LAN encompasses a broad set of 

requirements as cited in The Ethernet Sourcebook : [Ref. 2:p. 

13] 

relatively high data rates (typically 1 to 10M bits per 
second) ; 

- geographic distance spanning about one kilometer 
(typically within a building or a small set of 
buildings) ; 

ability to support several hundred independent devices; 



simplicity, or the ability to provide the simplest 
possible mechanisms that have the required functionality 
and performance; 

good error characteristics, good reliability, and minimal 
dependence upon any centralized components or control; 

efficient use of shared resources, particularly the 
communications network itself; 

stability under high load; 

fair access to the system by all devices; 

easy installation of a small system, with graceful growth 
as the system evolves; 

- ease of reconfiguration and maintenance; and 

low cost. 

B. BASIC LAN IMPLEMENTATION CONSIDERATIONS 

There is a wide variety of available technology to choose 
from in implementing a LAN. The optimal LAN for a given 
application is a trade-off between the number of users, their 
geographical distribution, the data rates required, the 
applications that must be supported, and user-justifiable 
costs [Ref. 3:p. 179]. The factors used to sort out the 
different technologies in making a decision are: hardware 
configuration, network topology, connectivity, data 
transmission rate, physical media, interfaces, flow control, 
and collision detection and avoidance. [Ref. 4:p. 8] 



II. ETHERNET LOCAL AREA NETWORKS 

This chapter provides a brief introduction on the history 
of Ethernet, basic components, theory of operation, and 
performance characteristics. 

A. HISTORY OF ETHERNET 

The co-inventors of Ethernet, Robert M. Metcalfe and David 
R. Boggs, created Ethernet at the Xerox Palo Alto Research 
Center in May of 1972. The name "Ether" was taken from the 
refuted physical theory of the "luminiferous ether" that was 
once thought to be the passive medium that served in the 
propagation of electromagnetic waves through space, such as 
carrying light from the sun to the earth. [Ref. 2: p. xi] The 
rationale behind using the term "Ether" was to use a general 
description of the medium used to carry transmissions through 
their experimental network. 

Ethernet design started with the fundamental idea of 
packet collision and retransmission developed in the Aloha 
Network at the University of Hawaii. [Ref. 5:p. 396] The 
Aloha Network is a star network that uses an outgoing 
broadcast channel and an incoming multi-access channel. There 
is no central controller assigning access to the channel, so 
each radio terminal uses a random access procedure to 
determine when to transmit. The penalty for the elimination 



of any central control is collisions caused by two terminals 
transmitting at the same time. This required the terminals to 
wait a random interval of time and then retransmit. 

The main difference between Ethernet and the Aloha Network 
is Ethernet's ability to support many-to-many communication 
with a single broadcast multi-access channel. 

B. EHTERNET BASIC COMPONENTS 

An Ethernet uses four basic components: the "Ether," 
transceivers, interfaces, and controllers. 

The "Ether" transmission medium, can be twisted pair wire, 
thin or wide coaxial cable, or optical fiber cable. Ethernet 
over unshielded twisted pair wire provides a practical and 
economical transmission medium. The ability to use a 
currently installed wiring system within a building reduces 
the cost of installation by eliminating the costly labor and 
material expenses of adding the network over coaxial cable. 
The use of twisted pair wire can support both baseband and 
broadband data transmission. Network moves, changes, 
diagnostics, and cable management are simple and flexible in 
an environment with unshielded twisted pair wire with a 
centrally located telephone wiring closet. The nodes can be 
reassigned by moving cross-connect wires on the punch-down 
block in the telephone wiring closet. When wired in 
hierarchical star configuration, the network can be segmented 
into logical subnets to facilitate fault isolation and provide 



4 



a control point for troubleshooting. [Ref. 6:p. 102] The 
major disadvantage of twisted pair wire is the distance 
limitation of its signal of 360 feet from the workstation to 
the central telephone wiring closet. 

The mechanical properties of coaxial cable makes it 
possible to tap in at any point without severing the cable or 
producing excessive RF leakage. It is suitable for 
transmitting high frequency signals while resistant to 
electrical interference. It is compatible for both baseband 
and broadband transmissions. Although coaxial cable costs 
more than twisted pair wire, the simpler installation and 
better electrical characteristics have made it the choice for 
most local area networks [Ref. 7:p. 50]. 

Optical fiber cables are more expensive than coaxial cable 
or twisted pair wire due to its construction. It is also 
difficult to tap due to the high coupling losses that can 
occur. Its major use is for long distance links or for areas 
where electrical interference is a problem. Increasingly, it 
is used for backbone networks and for some LANs because of its 
high bandwidth. 

The transceiver links the workstation to the cable using 
a pressure tap. The pressure tap connects to the cable 
without cutting it to insert a connector and avoids the need 
to interrupt network service while installing a new 
workstation. An alternate method of connecting the 
transceiver to the cable is to use a T-connector which will 



disrupt network service during installation. The two 

connector ends attach to the break in the cable and the t- 

adaptor end connects to the workstation's transceiver. The 

transceiver performs four essential functions: [Ref. 2:p. 20] 

transfers transmit data from the controller to the 
transmission system; 

transfers receive data from the transmission system to 
the controller; 

indicates to the controller that a collision is taking 
place; and 

provides power to the transmission system. 

An interface serializes and deserializes the parallel data 
used by the workstation. Each interface contains the hardware 
necessary to compute a 16-bit cyclic redundancy checksum (CRC) 
on serial data while transmitting and receiving. [Ref. 5:p. 
399] The checksum protects only against errors in the 
transmission medium and not for errors in the parallel 
portions of the interface hardware or workstation. It is 
possible to use higher-level software checksums for 
applications requiring a higher degree of reliability. 

The transmitting interface uses a packet buffer address to 
serialize the word count and phase encode the variable number 
of 16-bit words taken from the workstation's memory which pass 
to the transceiver. A start bit precedes the 16-bit words and 
the CRC follows the 16-bit words. The receiving interface 
will detect a carrier signal on the transmission medium and 
will use the start bit to acquire bit phase. If the carrier 



stays on the transmission medium, the interface will decode 
and deserialize the incoming bits depositing 16-bit words in 
a packet buffer in the workstation's memory. 

When the interface detects the absence of a carrier signal 
a check of the integral number of 16-bit words received 
against the CRC verifies capture of a complete error free 
packet. The last 16-bit word received is assumed to be the 
CRC and after checking for a complete packet the CRC is 
discarded by not being copied into the packet buffer. The 
interface will contain hardware to check the address of the 
packet to identify packets addressed to that workstation for 
packet processing. A destination address of zero is a 
broadcast packet and will be received by all the workstations. 
The controller is the workstation's low-level firmware 
or software for getting packets onto and out of the 
transmission medium [Ref. 5:p. 400]. It is the responsibility 
of the source workstation to detect a collision of its packet 
on the transmission medium and to generate a new random 
retransmission interval based on the updated collision count 
to resend its packet. The Binary Exponential Backoff 
algorithm is successful in reducing collisions during a heavy 
load on the network by increasing the retransmission interval 
causing retransmission traffic to back off to sustain channel 
efficiency [Ref. 5:p. 400]. 



C. ETHERNET THEORY OF OPERATION 

The IEEE and the American National Standards Institute 
(ANSI) officially adopted Ethernet as ANSI/IEEE Standard 802.3 
Carrier Sense Multiple Access with Collision Detection 
(CSMA/CD) Access Method and Physical Layer Specification in 
June of 1984 [Ref. 2:p. xv] . The United States federal 
government adopted Ethernet in FIPS PUB 107 as a standard for 
federal government use in 1984. 

1 . Network Topology 

The network topology of Ethernet is that of an 
uprooted tree composed of separate bus segments. The 
significance of this arrangement is one of simplicity by 
providing only one path through the transmission medium 
between any source and destination. The benefit of having 
this arrangement eliminates the possibility of a transmission 
packet interfering with itself by the packet repeatedly 
arriving at the intended destination by paths of different 
lengths. This arrangement prevents redundant connections and 
provides potential of the convenient addition of workstations 
to the net with minimal network interruption. The maximum 
length of the transmission medium for 3Com's EtherSeries 
baseband network is 1000 feet for each cable segment and 
allows a maximum of two repeaters between two workstations. 

2. CSMA/CD 

CSMA/CD (IEEE 802.3) provides straightforward control 
and can be characterized as "every user for itself" [Ref. 8:p. 

8 



64]. Ethernet CSMA/CD does not use a central controller for 
transmission medium access control or transmission medium 
access control management frames. A workstation desiring to 
transmit data is required to "contend" for the transmission 
medium. The workstation contending for the transmission 
medium checks for a carrier on the medium. When a carrier is 
detected the workstation waits until the medium is quiet and 
then begins to transmit. The workstation controls the net 
until all its data is transmitted or until a collision is 
detected. The "collision window" is the short interval 
between when a workstation begins transmitting data and a 
second workstation attempts its own transmission. The 
"collision window" is a function of the end-to-end propagation 
delay which is a function of the time required to transmit the 
data-frame at the transmission medium bit rate and the 
propagation delay of the transmission medium. [Ref. 9:p. 52] 

When a collision occurs the workstation transmitting 
data will abort the transmission and begin jamming the 
transmission medium to alert all other workstations of the 
collision. This invokes the exponential backoff algorithm 
that determines a delay interval before a workstation can 
attempt to transmit data. [Ref. 8:p. 65] Each workstation 
computes a different interval to minimize repeated collisions. 
The randomness of the waiting period for retransmission and 
unpredictable workstation control of the transmission medium 
makes the network availability fair for all workstations. 



3 . Broadband vs. Baseband 

Ethernet LAN's can use either broadband or baseband 
data transmissions. The decision of which method to use 
depends on the requirements of the network, cost of 
implementation, network expansion, and network maintenance. 

Broadband networks are more costly due to the hardware 
requirements needed to support the transmission of analog 
data. All workstations require RF modems to modulate and 
demodulate data transmitted over the network. The advantage 
of analog transmissions is the ability to transmit video, 
data, and voice data over one transmission medium. 

The key elements of a broadband system are the headend 
and distribution network. The headend is a hardware device 
that all data must pass through and there is only one path 
from a workstation to the headend. The distribution network 
consists of the cabling, branches to the bus, and cable drops 
between the branches and individual workstations and shared 
peripheral devices. Data transmissions are unidirectional 
which requires a separate frequency channel on the cable or a 
second cable to accomplish 2-way communication. The inbound 
channel carries data transmissions from the modem to the 
headend and the outbound channel carries data transmissions 
from the headend to the modems. Amplifiers increase the 
possible distance of the network and reduce signal 
attenuation. 



10 



Baseband networks use a bidirectional transmission 
medium to transmit digital data at a rate of 10Mbps [Ref. 
10: p. 10]. Baseband network length is limited to one to two 
kilometers. The lower cost of baseband networks, their ease 
of installation, and overall simplicity highlight their 
advantage. 

D. ETHERNET PERFORMANCE CHARACTERISTICS 

The performance characteristics of an Ethernet baseband 
LAN are measured on: data throughput, attached device 
connectivity, network response time, error types and error 
rates, fairness in access, and reliability [Ref. 7:p. 111]. 

Data throughput depends on the load condition of the 
Ethernet LAN and data packet size. John Shoch and Jon Hupp 
in their study on the performance of Ethernet LAN's reported 
that as the network load approached 9 percent the network's 
throughput curve leveled out at a level above 96 percent. 
[Ref. 11 :p. 718] When larger packets are compared to the 
collision interval the network is less susceptible to 
collisions and the data throughput will remain high. 
Conversely, the reduction in packet size increases the chances 
for collisions decreasing throughput as the packet size 
approaches the collision interval. 

The Ethernet LAN provides excellent connectivity. This is 
due to its passive broadcast medium which allows relative ease 
in adding or moving peripheral devices on the network. 



11 



The results of John Shoch and Jon Hupp in documenting the 
performance of Ethernet under normal loads indicated that 
workstations rarely waited for access, error rates were very 
low and few packets were lost [Ref. ll:p. 720], As a result 
of fairness in access and infrequent data collisions 
workstation response time is negligible. 



12 



III. 3COM NETWORK 

The 3Com EtherSeries baseband network version 2.4 provides 
a fast and powerful system for communicating and sharing 
information with other IBM or IBM-compatible PC's. Ether- 
Series utilizes the IEEE 802.3 Ethernet industry standard and 
MS-DOS. 

EtherSeries when using a network server connected to the 
network allows use of the five EtherSeries products: [Ref. 
12:p. 1-1] 

EtherLink; 
EtherShare ; 
EtherPrint; 
EtherMail; 
- EtherMenu. 

In addition, application programs and data files for other 
computer software can be utilized using DOS commands. 



13 



IV. 3COM HARDWARE 

The hardware requirements for the 3Com EtherSeries network 
include: an IBM PC, EtherLink card, coaxial cable, BNC T- 
Adapter, transceiver cable and terminators. 

A. WORKSTATIONS 

The workstation requires use of an IBM or IBM-compatible 
PC with the following requirements: 
one diskette drive; 

128K of memory or 192K when using EtherMail; 
an 80 character display; 
an available expansion slot; 
PC DOS version 2.0. 

B. ETHERLINK 

The EtherLink is a printed circuit board that plugs into 
an expansion slot in the IBM PC. The EtherLink sends and 
receives information across the network. 

C. COAXIAL CABLE 

EtherSeries can use either thick or thin coaxial cable. 
Thin Ethernet coaxial cable uses 50 ohm RG-58 A/U cable (0.2 
inch diameter) and uses BNC connectors. The maximum length of 
a cable segment is 1000 feet and a minimum distance of three 
feet is required between workstations or transceivers. Thick 



14 



Ethernet coaxial cable is 0.4 inch diameter cable that uses N- 
series connectors. The maximum length of a cable segment is 
1640 feet and the minimum distance between workstations or 
transceivers is 7.5 feet. When using EtherLink with thick 
cable an external transceiver is required or N-series to BNC- 
series will be required. [Ref. 12 :p. A-2] A repeater allows 
combining either thick Ethernet of thin Ethernet cable 
segments. The repeater has the same electrical 
characteristics of a transceiver. A limit of only two 
repeaters are allowed between any two workstations and only a 
combination of 100 workstations and repeaters are allowed per 
cable segment [Ref. 12 :p. B-6]. 

D. BNC T-ADAPTER 

The BNC T-adapter provides the link between the coaxial 
cable and the transceiver cable to the EtherLink card. The 
Thin Ethernet coaxial cable is attached to the T-adaptor using 
the BNC adapters. 

E . TERMINATORS 

Two terminators are required in the EtherSeries network. 
The terminators attach to the T-adapters or coaxial connectors 
on the T-adapter at both ends of the network bus. One of the 
terminators is grounded to an AC wall plate to ensure the 
reliability of the network. 



15 



V. 3COM SOFTWARE 

This chapter provides a general description of each of the 
software components of the EtherSeries network. It is not 
intended to provide a detailed presentation, but to describe 
their major attributes. 

A. ETHERSHARE 

EtherShare is the software interface of the EtherSeries 
network. EtherShare allows workstations to share a single 
hard disk which may be contained in the network server. The 
network server controls hard disk resources, printers, and 
electronic mail service. 

The hard disk is divided into volumes that can be any size 
from 64KB to 32MB. The volumes can be viewed as a 
workstation's own diskettes. The volumes can be accessed 
after logging on to EtherShare and linking to an EtherShare 
volume to a drive specifier on your PC. The normal drive 
specifiers for EtherShare volumes are D: , E: , F: , and G: with 
C: reserved for PC's that contain their own hard disks. 

Security of the volumes is determined by the user when 
creating EtherShare volumes. The only practical accesses are 
public and shared. The owner of a private volume can change 
the access level to either public or shared. A public volume 
allows read only access to users other than the owner. The 



16 



owner must determine what degree of access others will have to 
his volume. If the owner generates a password to access the 
volume only those granted the password can use that volume. 
If no password is generated anyone can access the volume. 
Shared volumes allow others to have read-write access if they 
are granted the password to the volume. Both public and 
shared volumes can be accessed by multiple users at the same 
time. 

B. ETHERPRINT 

EtherPrint permits many users to print programs, data, and 
text files on a shared printer. When the workstation is 
linked to the network server print files from the workstation 
are "spooled" on the network server to be printed on the 
printer selected in the order they arrive at the server. 
Three printers can be attached to a server and only one of 
these may be a serial printer. 

The benefit of EtherPrint is its ability to make programs 
run faster. When using EtherPrint data is sent to the server 
at the speed of the network not the speed of the printer [Ref . 
12:p. 2-1]. The delay in responding to print reguests is very 
slow. Also, after an application is completed and the output 
file is to be printed the workstation is allowed to do other 
useful work. The output file is gueued onto the server to be 
printed in order of arrival. 



17 



C. ETHERMAIL 

EtherMail allows users to send and receive messages 
through the network server. The network server acts as a 
mailbox that distributes mail to their destination when that 
user is online or saves the message until that user logs on 
the network. The server will notify users if they have mail 
waiting for them the next time they log on the network. Also, 
the server will notify the sender if the message is 
undeliverable. Networks with multiple servers must have 
EtherMail software on each of the servers in order to 
distribute messages to the users of that server. 

EtherMail is a screen-oriented message editor. The 
message editor can be used to create distribution lists, 
documents, programs, batch files, and other text related 
files. In addition, DOS files can be attached to an EtherMail 
message. 

D. ETHERMENU 

EtherMenu allows users to select the task they wish to 
perform. The standard EtherSeries menu includes a Main Menu, 
EtherSeries Utilities Menu, Dos Utilities Menu and Network 
Volumes and Printers Menu. EtherMenu can be modified to meet 
the needs of the network users. 



18 



VI. CONCLUSIONS AND RECOMMENDATIONS 

Recommendations for the EtherSeries network relate to the 
LAN's management. 

A. LAN MANAGEMENT 

An effective LAN management plan requires good maintenance 
of the LAN and support from the vendors providing the 
equipment used. Prior evaluation of a vendor's products and 
services to be provided are critical in the life cycle of a 
LAN. 

B. CONFIGURATION MANAGEMENT 

The life cycle of a LAN always includes changes over time. 
Periodical evaluation and reconfiguration of the LAN are 
needed. Configuration management entails optimizing the 
resources of the LAN and maximizing throughput and data 
transmission reliability. A method to provide essential 
management of the network a database must be kept of the 
system's configuration, operational problems that have 
occurred and problems encountered while reconfiguring the 
network. 

C. OPERATIONS AND MAINTENANCE 

A plan must be developed to ensure a maintenance schedule 
is developed for hardware and software and a history of work 



19 



done is compiled for future reference. Included in this area 
a plan should be developed to determine future growth 
requirements and a backup system developed to minimize damage 
caused by network down time. 

D. PERFORMANCE MONITORING 

Performance monitoring of the network provides information 
necessary for optimizing the networks configuration. Typical 
information required concerns LAN loading, traffic 
information, failure situations, and network choke points. 

E. SECURITY 

Ethernet systems are not designed for network security. 
A user management plan is required to provide mechanisms to 
control physical access and logical access to the network. 



20 



APPENDIX 
3COM ETHERSERIES LAN USER MANUAL 

This appendix is a User Manual for the 3COM EtherSeries 
Network version 2.4. The manual is specifically written for 
use in the Administrative Sciences Information Systems lab 
at the Naval Postgraduate School located in Ingersoll Hall 
room 1-224. 



21 



TABLE OF CONTENTS 

I. INTRODUCTION 24 

A. GETTING STARTED 24 

B. LOGON PROCEDURES 24 

C. ETHERMAIL (EMAIL) 25 

D. ETHERMENU (EMENU) 25 

1. EtherSeries Utilities 25 

2. DOS Utilities 25 

E. ETHERPRINT (EPRINT) 26 

F. HELP 26 

G. ETHERSHARE (ES) 26 

H. ETHERPRINT (EP) 27 

II. GETTING STARTED 28 

III. LOGON PROCEDURES 29 

IV. EMAIL 32 

A. STARTING EMAIL 32 

B. CREATING A MESSAGE 33 

1. The Message Header 33 

a. General Rules for Header 

Information 34 

2. Entering Message Text 34 

a. Margins and Tabs 35 

b. Special TExt Editor Control Keys 36 

c. (F6) Marking Text 36 



22 



3. Leaving the Editor 38 

C. SAVING THE FILE 39 

D. CLASSIFYING MESSAGES 39 

V. EMENU 41 

A. ETHERSERIES UTILITIES 41 

1. HELP 41 

2. Link Network Volumes and Printers 41 

3. "Tour" the Network 41 

4. LOGOUT 42 

B. DOS UTILITIES 42 

1. HELP 42 

2. List File Directory 42 

3. Copy Files 43 

4. Display a File on the Screen 43 

5. Format a Diskette 43 

6. Run a Program 44 

VI. EPRINT 45 

A. PRINTING A FILE 45 

VII. HELP 46 

VIII. ETHERSHARE (ES) 47 

A. ETHERSHARE COMMANDS 47 

IX. ETHERPRINT (EP) 49 

A. ETHERPRINT COMMANDS 49 

B. PRINTI SCREEN COMMAND 49 

X. GLOSSARY 50 



23 



I. INTRODUCTION 

Welcome to the Naval Postgraduate School's 3Com 
EtherSeries Network. The purpose of this manual is to 
provide a step-by-step guide in learning the 3Com 
EtherSeries LAN at the Naval Postgraduate School. The 
user's manual is adapted from EtherSeries User's Guide 
Version 2.4 May, 1985. 

The EtherSeries Network is located in Ingersoll room 
224. This network has 3 IBM XT and 2 IBM PC computers 
connected to the 3Com EtherSeries Network. The network uses 
a 70 megabyte 3Com 3Server3 server. 

The following outline highlights the topics and features 
of the EtherSeries LAN 

A. GETTING STARTED 

The getting started section will define the meanings of 
key words and letters used within the user's guide to 
describe user actions. 

B. LOGON PROCEDURES 

The logon procedure describes the repetitive logon 
requirements of the EtherSeries network, the setup of logon 
names, passwords, software and drive specifiers. 



24 



C. ETHERMAIL (EMAIL) 

The EtherMail section describes the capabilities of 
EtherSeries electronic mail system. Also, a step by step 
user guide of each EtherMail option is presented. 

D. ETHERMENU (EMENU) 

The EtherMenu provides access to the EtherSeries 
Utilities and DOS Utilities. 

1. EtherSeries Utilities 

The EtherSeries Utilities provides the following 
options: 

- A Help menu that provides a one screen description of 
the 3COM EtherSeries network. 

- The option, Link Network Volumes and Printers, allows 
users to: 

a. Link, unlink, create, modify and delete volumes. 

b. Link and unlink printers. 

c. Create, modify and delete users. 

d. No options available for the server selection. 

e. Displays the help screen detailing keyboard 
options. 

- "Tour" the Network provides an abbreviated 
indoctrination of the EtherShare (ES) and EtherPrint 
(EP) commands. 

2. POD Utilities 

The DOS Utilities provides the following options: 

- A Help screen providing a brief description of the DOS 
Utility option capabilities with EtherMenu. 

- Allows users to list the directories of available disk 
drives (A:, B: , C: , D: , E:, F: , and G:). 



25 



- Allows users to make copies of files. 

- Allows users to display files on the screen. 

- Allows users to format diskettes. 

- Allows users to execute a program while logged on the 
network. 

E. ETHERPRINT (EPRINT) 

The EtherPrint option provides a help screen detailing 
how to print a file. 

F. HELP 

The Help option details how to start EMAIL, EPRINT, and 
application programs. Also, the user is notified that disk 
drive A: is the default drive for user applications. 

G. ETHERSHARE (ES) 

This section details the procedures to follow when 
executing the following EtherShare commands: 

- (ES LOGIN) Logging onto the server. 

- (ES LOGOUT) Logging out from the server. 

- (ES LINK) Linking to an EtherShare volume. 

- (ES UNLINK) Unlinking from an EtherShare volume. 

- (ES DIR) List all linked user volumes. 

- (ES CREATE) Creating a new volume. 

- (ES MOD) Modifying an existing volume. 

- (ES DEL) Deleting an existing volume. 

- (ES UDIR) Listing all network users. 

- (ES UCREATE) Creating new user names. 



26 



- (ES UDEL) Deleting user names. 

- (ES UMOD) Modifying your user password. 

- (ES SDIR) Lists all servers. 

- (ES HELP) The Help screen is currently unavailable. 

H. ETHERPRINT (EP) 

This section details the procedures to follow when 
executing the following EtherPrint commands: 

- (EP LINK) Linking a printer to a server. 

- (EP UNLINK) Unlinking a printer from a server. 

- (EP DIR) Lists the printers supported by the server. 

- (EP HELP) Provides help information for EP commands. 



27 



II. GETTING STARTED 

Getting started with the EtherSeries network helps users 
to understand the methodology used in the user's manual. 
The following explanations and examples will apply: 

- all user commands require the user to hit the enter or 
return key to execute the command. 

- XXXXXX will denote input data to be provided by the 
user. 

- (CTRL- ALT-DELETE) is an example of control keys that 
must be entered at the same time. This example would be 
used if the user desired to re-boot the PC. 

- (CTRL-BREAK) is used to cancel EtherShare and EtherPrint 
commands. The user will be able to return to the 1DIR 
screen. 

- Input data for all user names, passwords, and commands 
can be entered in either upper or lower case letters. 
Upper case letters are used in this manual to highlight 
user input requirements. 



28 



III. LOGON PROCEDURES 

Logging onto the EtherSeries network is a four step 
process. 

1. Turn on the PC. 

2. Enter the corresponding user name that applies to the 
PC you wish to use. The current legal user names 
available on the network are: ENET1, ENET2, ENET3 , 
ENET4, and ENET5. 

3 . Enter the current password to access the network 
server. The current password is GENERAL. 

4. Enter the current password to access the network 
user's private volume. The current password is 
GENERAL. 

The following example shows the correct procedure for 
logging on the network: 

Your name? ENET1 

Password? ( GENERAL 

ENET1 logged in to NORMS. 

Your EtherShare drives are D: through G: 

Password? ( GENERAL 

NORMS. SYS2 linked to D. 

NORMS linked to PRN. 

In the event of an unsuccessful logon enter (CTRL-ALT- 
DEL) to re-boot the PC and try again. If you are still 
unsuccessful after correctly entering the proper user name 
and passwords, notify the network manager. 



29 



You have now entered the EtherSeries network. The 
network is capable of using drive specifiers D: , E: and G: . 
Drive D: contains the Server NORMS and drive E: contains the 
volume INBOX which is used as the mailbox on the server to 
store electronic mail. 

EtherShare volumes can have three kinds of access: 
private, public, or shared. All EtherShare volumes are 
created with private access. After files have been loaded, 
the access may be modified to public or shared. (12 : C-l) 
Each of the INBOX volumes for the 6 workstations are 
designated private volumes. 

Each of the different EtherShare volume types have 
different access restrictions. Only the owner can log on. 
Public volumes may be shared by many users at the same time, 
but have read-only access. Only shared volumes can be 
accessed by many users at the same time with both read and 
write capability. 

Semaphores are provided for use with shared access 
volumes and provide a means to protect against the loss of 
data that may occur when multiple programs update the same 
file. Three semaphore operations are provided by EtherShare 
servers: LOCK/WAIT, LOCK/RETURN, and UNLOCK. Any program 
using shared access volumes must be modified to include 
semaphores if they will update files in shared volumes. 
[Refl. 12:p. C-2] 



30 



At this point you will looking at the 1DIR screen on 
drive D: listing the available user options: 

- SYS2 the current network server volume. 

- APPS the subdirectory containing application programs 
available on the network server. 

- EMAIL the subdirectory containing EMAIL system files. 

- EMENU the subdirectory containing EMENU system files. 

- EPRINT the subdirectory containing EPRINT system files 

- EMAIL.BAT the batch file for starting EMAIL. 

- EMENU.BAT the batch file for starting EMENU. 

- EPRINT.BAT the batch file for starting EPRINT. 

- HELP. BAT the batch file for displaying 1DIR screen help 
information. 



31 



IV. EMAIL 

EMAIL allows users to send and receive messages through 
the network server volume (NORMS) . Each workstation has a 
private volume called INBOX located on server drive E: which 
contains that workstation's mail. 

A. STARTING EMAIL 

The EMAIL program can be started after logging on the 
network. The 1DIR screen will appear and the user starts 
EMAIL by selecting EMAIL.BAT with the down arrow key and 
pressing the enter key or by typing: 

D> EMAIL.BAT 

The first EMAIL screen will appear displaying in 
numerical order received mail in your INBOX volume. If 
there is no mail the screen will be blank. Immediately upon 
starting EMAIL the program will check to see if you have any 
mail waiting for you on the server mailbox. The status line 
at the bottom of the screen will tell you to press F8 to 
receive your mail. 

The bottom line on the screen lists the following EMAIL 
function keys: 

- Fl HELP Displays a description of the function keys. 

- F2 SHOW Displays contents of message/attachment 
indicated by the cursor. 

- F3 DELETE Will delete the indicated message/attachment 
from your INBOX folder. 



32 



F4 PRINT Prints a hard copy of the indicated 
message/attachment . 

F5 FILE Will copy the message/attachment to a DOS 
file. 

F6 REPLY Will create a new message which is a reply to 
the message indicated by the cursor. 

F7 FORWARD Will forward a copy of the indicated 
message to someone else. 

F8 GET Will check the mailbox on the server for new 
messages and will transfer them to your INBOX folder. 

F9 NEW Will create a new message. 

F10 EXIT Will return the user to the 1DIR screen. 



B. CREATING A MESSAGE 

Press F9 to start the message editor screen. The 
message screen contains the message header, message text, 
the EMAIL status line and function key display. 

1 . The Message Header 

The message header must be entered first before the 
status line and the function key line will be displayed at 
the bottom of the screen. The message header is divided in 
the following five fields: 

- FROM: the from line is automatically generated using 
the user workstation's name. 

- TO: the to line is a required field and must be entered 
by the user using valid names on the server. Multiple 
addresses are allowed. 

- CC: the carbon copy line is optional and allows the 
user to send himself and others a copy of the message. 

- SUBJ: the subject line is optional and only one line of 
data is allowed for the subject. 



33 



- ATTACH: The attachment line is optional and allows the 
user to attach up to 26 DOS files to a message. In 
order to attach a DOS file the drive specifier, file 
name, and file extension is required. If necessary the 
DOS file's path name will be required. 

Example: B : NAME . EXT 

B : \PATH\NAME . EXT 

a. General Rules for Header Information 

When sending a message to multiple users 
separate the names with a comma or semicolon or enter a 
comma or semicolon and hit enter to start a new line for 
user names. The same rule applies for multiple CC: user 
names and DOS file attachments. 

When invalid names are used a message will 
appear on the status line after sending the message 
notifying the user the server is unable to deliver the 
message. If multiple addresses are used and at least one 
user address is invalid a message will appear on the status 
line asking the user if the message should be sent anyway. 
The user should enter Y to send the message or N to leave 
the message in the user's inbox folder. 

The user can erase an entire line of input on 
the header line data by pressing the ESC key once. If the 
user presses ESC key twice the message will be aborted and 
returns the user to the original EMAIL display. 
2 . Entering Message Text 

Upon completion of the header information the status 
line will display whether the screen editor is in the insert 



34 



mode or type-over mode and displays EDIT for edit mode. The 
editor uses the INS key to toggle between the insert and 
type-over mode. 

The function key line at the bottom of the screen 
displays the following information: 

- Fl — HELP displays explanations of the function and 
special editor control keys. 

- F2 — FILL fills edited paragraphs out to the margins. 

- F3 — DELW deletes the word indicated by the cursor 
location. 

- F4 — DEL2 deletes text from the cursor position to the 
end of the current line. 

- F5 — DELL deletes the entire line of text. 

- F6 — MARK marks text to be moved, copied or deleted. 

- F10 — DONE exits the editor and returns to the first 
EMAIL screen. 

a. Margins and Tabs 

The text editor provides for automatic word wrap 
so it is unnecessary to hit the return key for each line of 
input. There is no option to alter the margins or tab 
settings for the text editor. Each line is 65 characters 
long and the tab key moves over four spaces to the next tab 
setting. 

Whenever the tab key is used the left margin 
will default to that location on each succeeding line until 
the return key is used. Also, when using the move function 
to move tabular information always start the move location 



35 



at the far left margin of the screen to retain the same 
location after moving the data. 

b. Special Text Editor Control Keys 

The following special keys on the keyboard 
perform the following editing and control functions: 

- Arrow Keys control Up, Down, Left, and Right Cursor 
control . 

- Home moves the cursor to the top left corner of the 
screen. 

- CTRL-Home moves the cursor to the lower left corner of 
the screen. 

- END moves the cursor to the end of the current line. 

- END END moves the cursor to the end of the paragraph. 

- ENTER inserts a new line at the current cursor 
position. 

- CTRL-ENTER moves the cursor to the beginning of the 
next line. 

- PGUP displays the previous screen of text. 

- PGDN displays the next screen of text. 

- DEL deletes the current character the cursor is under. 

- INS toggles between INSERT and TYPE-OVER mode. 

- BACKSPACE backspaces and deletes the previous 
character. 

- TAB moves the cursor to the next word or tab stop. 

- SHIFT-TAB moves the cursor to the previous word or tab 
stop. [Ref. 12:pp. 6-7 — 6-9] 

c. (F6) Marking Text 

Marking text is used to mark blocks of text 
which can be moved, copied or deleted. Regardless of 
whether you want to move, copy or delete, the first step is 



36 



always to mark the beginning and end of the block of text. 
The blocked text will be highlighted and you can then delete 
the text, or position the cursor anywhere in the document 
and move or copy the text to that location. [Ref. 12 :p. 6- 
19] 

Example: Deleting Blocked Text 

1. Place the cursor under the beginning of the text you 
wish to delete. 

2. Press the F6 function key. 

3 . Move the cursor under the ending location of text to 
be deleted and press the F6 function key again. 

4. Press the F9 function key to delete. 

5. Press the F9 function key again to confirm. 

Example: Moving Blocked Text 

1. Move the cursor under the beginning of the text you 
wish to move. 

2. Press the F6 function key. 

3 . Move the cursor to the ending location of text to be 
moved and press the F6 function key again. 

4. Move the cursor to the screen location you wish to 
have the blocked text moved to and press the F8 
function key. 

Example: Copying Blocked Text 

1. Move the cursor under the beginning of the text you 
wish to move. 

2. Press the F6 function key. 

3. Move the cursor to the ending location of text to be 
copied and press the F6 function key again. 

4. Move the cursor to the screen location you wish to 
have the blocked text copied to and press the F7 
function key. 



37 



The F10 function key will end the MARK mode and 
allow the user to resume editing. Caution should be used 
when moving and copying text because no formatting 
information is maintained which may require reformatting 
your text after these operations. 
3 . Leaving the Editor 

Pressing the F10 function key causes the current 
message to be displayed with a new status line and a new set 
of function keys. The status line will remind the user to 
press F6 to send the message. The function keys at the 
bottom of the screen perform the following tasks: 

- Fl HELP displays an explanation of the function keys. 

- F2 NEXT will notify the user on the status line that 
the message was not sent and will ask if you wish to 
save it. Enter Y to save the message or N to delete the 
message. The message will be labeled In Progress and 
saved in the user's mail folder. 

- F3 DEL will delete the current message. The status 
line will ask the user to press F3 again to confirm 
deletion of the message. 

- F4 PRNT will print the current message. 

- F6 SEND will send the message to the addressees of the 
message. Any addressees that are invalid will cause the 
server to notify the user of any addresses that can not 
be located. The user can enter Y to send the message 
anyway or N to return to the previous screen. 

- F7 EDIT will allow the user to re-edit the current 

message. 

- F9 NEW will notify the user that the current message 
was not sent and will ask the user to save enter Y or N 
to delete the current message and start a new message. 
The saved message that was not mailed will be labeled In 
Progress in the user's mail folder. 



38 



- F10 EXIT will cause the status line to ask the user to 
save or delete the current message. Enter Y to save the 
message as In Progress or enter N to delete the message. 



C. SAVING THE FILE 

When editing a large document the file should be saved 
periodically to protect against an unexpected power failure 
or system failure. The text editor can edit files as large 
as 25,000 characters. All changes are kept in computer 
memory until you save the file on diskette or an EtherShare 
volume (12:6-25). The following steps outline this 
operation: 

1. Press F10 to leave the editor. 

2. Press F10 again to get status line request to save 
the message. 

3. Enter Y to save the message. The status line will 
inform you of the file's number. 

4. Move the cursor to select the file just save and 
press F2 to show that file. 

5. Press F7 to edit the file you have just saved. 

D. CLASSIFYING MESSAGES 

Current user messages are labeled in numerical order. 
An asterisk will indicate a message that has not been read. 
After the message has been read the asterisk will disappear. 
Users can classify their messages by entering a one letter 
symbol to personalize your message file. For example R can 
be used to signify messages that need to be replied to or a 
D could be used for messages you wish to delete at some 



39 



later time. The letter used will not be erased if the 
message is read. 

To personalize your messages move the cursor to the 
message desired and enter your special letter code over the 
number signifying that message. The letter will appear to 
the left of the date you received that message. 



40 



V. EMENU 

EMENU provides access to the EtherSeries Utilities and 
DOS utilities. EMENU can be started from the 1DIR screen by 
moving the down arrow to select EMENU.BAT and pressing the 
enter key or by typing: 

D> EMAIL. BAT 

A. ETHERSERIES UTILITIES 

EtherSeries Utilities can be selected by pressing the 1 
key or using the arrow keys to highlight EtherSeries 
Utilities and pressing the enter key. The ESC key will 
allow the user to return to the previous menu. Enter Y to 
return to the 1DIR screen. 

1. HELP 

The HELP screen can be selected by pressing the 1 
key or by using the up or down arrow keys to highlight HELP 
and pressing the enter key. The HELP screen provides a one 
screen description of the 3Com EtherSeries Network. 

2 . Link Network Volumes and Printers 

Users requiring to use this item should contact the 
network manager for permission to make changes to the 
volumes, printers, user names, and server. 

3 . "Tour" the Network 

The option "Tour" the Network can be selected by 
pressing the 3 key or by using the arrow keys to select 

41 



"Tour" the Network and pressing the enter key. The "Tour" 
will provide users with descriptive narration of EtherShare 
(ES) and EtherPrint (EP) commands. 
4. LOGOUT 

The option LOGOUT can be selected by pressing the 4 
key or by using the arrow keys to select LOGOUT and pressing 
the enter key. The user will now be disconnected from the 
EtherSeries Network. 

The user may log back on to the EtherSeries network 
by typing LOGIN to start the login procedure or by pressing 
the CIEL-ftLT-DSL keys at the sane tine. 

B. DOS UTILITIES 

The DOS Utilities option can be selected by pressing 2 
or by using the arrow keys to highlight DOS Utilities and 
pressing the enter key. The six DOS utility options may be 
selected by pressing the number of that option or by using 
the arrows keys to highlight that option and pressing the 
enter key. The ESC key will return the screen to the 
previous menu. 

1. HELP 

The HELP screen provides a brief description of the 
DOS Utility option capabilities. The user may press any key 
to return to the EMENU Main Menu screen. 

2 . List File Directory 

The List File Directory will display the directory 
of any of the available drive specifiers. The available 

42 



drives are: A:, B: , C: , D: , E: , F: and G: . If the 
directory is over one screen length the listing will 
automatically list only one screen at a time. The user must 
strike any key to continue the listing. The ESC key will 
return the user to the DOS Utilities Menu. 

Example: List Directory for what drive? (C: , D: , 
etc) : Dj. 

3 . Copy Files 

The copy files utility allows users to copy a single 
file or all the files on a diskette. 

Example: Copying a single file. 
Enter the drive and name of files to copy: A: Input. Ext 
Enter the drive and name of new files: B : Output . Ext 

Example: Copying multiple files. 
Enter the drive and name of files to copy: A: *. * 
Enter the drive and name of new files: C: *. * 

4 . Display a File on the Screen 

The option display a file on the screen will display 
an ASCII formatted file on the screen. Pressing the ESC key 
will return the user to the DOS Utilities Menu. 

Example: Displaying a file. 
Enter the drive letter and filename: C : Name . Ext 

5 . Format a Diskette 

The option format a diskette will format a user's 
diskette. Pressing the ESC key will return the user to the 
DOS Utilities Menu. 



43 



Example: Formatting a diskette. 

In what drive is the diskette to be formatted? Ai 
6 . Run a Program 

The option Run a Program will load and execute a DOS 
file program. 

Example: Run a Program. 
What is the name of the program to run? GAMES 
Enter additional parameters (RETURN to proceed) : Ai 

Do not type the drive specifier before the name of 
the program you wish to run. If a program is located on 
another drive, typing the drive specifier before the program 
name allows the menu system to locate only the main program 
file. It doe not change the current drive. Therefore, do 
not use this menu option to run a program that consists of 
multiple files and resides on another drive. EtherMenu will 
only locate the first file. Also, do not run a DOS command 
or application that is a .BAT file because the menu system 
will not be automatically restarted. [Ref. 12 :p. 1-8] 



44 



VI. EPRINT 

The EPRINT.BAT provides a help screen that describes how 
to print a DOS (ASCII) file. The EPRINT help screen can be 
selected by using the arrow keys to select EPRINT.BAT and 
then pressing the enter key or by typing: D> EPRINT . BAT . 

A. PRINTING A FILE 

To print a DOS file perform the following steps: 

1. Press any key to clear the HELP screen. 

2. Enter RUNPRINT B: FILENAME. EXT 

3 . Press the enter key to return to the previous 
screen. 



45 



VII. HELP 

The HELP option provides information on starting EMAIL, 
EPRINT, and application programs. The help screen can be 
selected by positioning the cursor at HELP. BAT and pressing 
the enter key. The user can return to the 1DIR screen by 
pressing any key to continue. 



46 



VIII. ETHERSHARE (ES) 

There are 14 EtherShare commands. The EtherShare 
Command screen can be generated by entering: D>ES. The ES 
command is selected by entering the command's number and 
pressing enter or by typing ES followed by the EtherShare 
command . 

Example: ES DIR 

Users that wish to make changes to the network's 
volumes, server, and user names must receive permission from 
the network manager prior to making any changes. 

A. ETHERSHARE COMMANDS 

1 — Login to the server. (LOGIN) 

2 — Logout from the server. (LOGOUT) 

3 — Link to an EtherShare volume. (LINK) 

4 — Unlink from a volume. (UNLINK) 

5 — List all volumes. (DIR) 

6 — Create a new volume. (CREATE) 

7 — Modify an existing volume. (MOD) 

8 — Delete an existing volume. (DEL) 

9 — List all users. (UDIR) 
10 — Create a new user. (UCREATE) 
11 — Delete an existing user. (UDEL) 
12 — Modify your user password. (UMOD) 



47 



13 — List all servers. (SDIR) 

14 — Receive help. (HELP) 
Selection 14 — Receive help is presently unavailable for 
selection on the network server. A server not ready 
response will be received. The user should enter a N to 
ignore the message and press any key to return to the 1DIR 
screen. 

Once an ES command is started which will change a user 
name, volume, or server the user can press the CTRL-BREAK 
keys simultaneously to cancel the operation. 



48 



IX. ETHERPRINT (EP) 

There are four EtherPrint commands. The EtherPrint 
command screen will appear after entering EP. The 
EtherPrint command may also be initiated by entering EP 
followed by the command. 
Example: EP DIR 

Users are required to receive permission from the 
network manager prior to altering printer and server links. 

A. ETHERPRINT COMMANDS 

1--Link to a print server (LINK) . 

2 — Unlink from a print server (UNLINK) . 

3 — List printers supported by the server (DIR) . 

4 — Receive help (HELP) . 

B. PRINT SCREEN COMMAND 

The EtherSeries network allows users to use the PRTSC 
key to print the users screen as if the printer is connected 
to your own workstation. The printout will be spooled out 
to the server and printed as soon as the printer is 
available. 



49 



X. GLOSSARY 



APPS 



the applications subdirectory on the 
EtherSeries main menu. 



CC: 



EtherMail message header address for users to 
receive carbon copies of the message. 



CTRL-ALT-DELETE keys used in combination to automatically 

log out from the EtherSeries server and reload 
the system's operating system. 



CTRL- BREAK 



CTRL-ENTER 



CTRL-HOME 



keys used in combination to escape from an 
EtherSeries operation. 

moves the cursor to the beginning of the next 
line of text when using the EtherMail editor. 

moves the cursor to the lower left corner of 
the screen when using the EtherMail editor. 



DRIVE SPECIFIER the DOS name used to identify a diskette 

drive or device with similar data storage 
capability. 



EMAIL.BAT 



the batch file that starts EtherMail. 



EMENU . BAT 



the batch file that starts EtherMenu. 



EPRINT . BAT 



the batch file that starts the EtherPrint 
instruction screen. 



LINK 



LOGIN 



PASSWORD 



the established connection across the 
EtherSeries network between a DOS drive 
specifier, printer, or volume. 

the procedure performed to access the 
EtherSeries network. 

the user generated private word assigned to 
user names and EtherShare volumes. 



PRIVATE VOLUME EtherShare volume access limiting to log 

on of owner. 

PUBLIC VOLUME EtherShare volume access granting read 

only access to all users other than the owner 



50 



SEMAPHORE 



having read/write access. A public volume 
without a password may be linked by any user 

a flag that can be unlocked or locked to 
indicate that a shared resource is available 



SHARED VOLUME 



UNLINK 



EtherShare volume access granting 
read/write access to all users at the same 
time. Shared volumes reguire semaphores to 
protect against loss of data caused by many 
users writing to a file simultaneously. [Ref. 
12:p. A-2] 

disconnect a link between the EtherSeries 
network and a DOS drive specifier, printer, or 
volume. 



USER NAME 



EtherShare names created by the network 
manager to identify network users or 
workstations . 



VOLUME 



the EtherShare designation use to divide up 
the hard disk on the server. The volume is 
assigned a name, access type, password and 
size. 



51 



LIST OF REFERENCES 



1. Forbes, M. , "Ethernet Role: To Link Desktop System," 
Computer Technology REview , Vol. 7, May 1987. 

2. Shotwell, R.E., The Ethernet Sourcebook . North-Holland, 
1985. 

3. Montrose, J.K., "How to Find the True Cost of a Local 
Area Network," Data Communications , April 1986. 

4. Liang, T. , "Local Area Networks: Implementation of 
Considerations," Journal of Systems Management . 8 
January 1988. 

5. Metcalfe, R.M. , and D.R. Boggs, "Ethernet: Distributed 
Packet Switching for Local Computer Networks," CACM, 
Vol. 19, July 1976. 

6. Schmidt, R. , "Twisted Pair Ethernet to Become a 
Standard," UNIXWORLD, October 1988. 

7. Gee, K.C.E., Introduction to Local Area Computer 
Networks, John Wiley & Sons, Inc., 1984. 

8. McConnell, J., Internetworking Computer Systems: Inter- 
connecting Networks and Systems , Prentice-Hall, Inc., 
1988. 

9. Halsall, F. , Data Communications, Computer Networks and 
SI . Addison-Wesley Publishing Company, Inc., 1988. 

10. Cheng, J., and Lew, H.K. , "A Hardware Platform for 
Interoperability," Computer Technology Review , Vol. 8, 
August 1988. 

11. Shoch, J.R. , and J. A. Hupp, "Measured Performance of an 
Ethernet Local Network," CACM , Vol. 23, December 1980. 

12. 3Com Corporation, EtherSeries User's Guide . Vol. 2.4, 
May 1985. 



52 



INITIAL DISTRIBUTION LIST 



No. Copies 



1. Defense Technical Information Center 2 
Cameron Station 

Alexandria, Virginia 22304-6145 

2. Library, Code 0142 2 
Naval Postgraduate School 

Monterey, California 93943-5002 

3. Prof. Norman Schneidewind, Code 54Ss 1 
Naval Postgraduate School 

Monterey, California 93943-5000 

4. Prof. Leon Sahlman, Code 54Sh 1 
Naval Postgraduate School 

Monterey, California 93943-5000 

5. LT David L. Andersland 1 
1207 Ynez Avenue 

Redondo Beach, California 90277-5119 



53 



Jll 

3-BC 




Thesis 

A4444 Andersland 
c.l 3Com EtherSeries Local 
Area Network. 



90 

■ ■ 



3 6 S 1 6 
3 7 'i 'I !i 



Thesis 

A4444 Andersland 

c. 1 

Area Network 



3Com -itue *->- — 



Loc?