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Artificial Traffic Generation of

ISO Transport Class IV Protocol

Data Units on an IEEE 802.3

10 Megabit CSMA/CD Local

Area Network

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Institute for Computer Sciences and Technology

Systems and Network Architecture Division

Washington, DC 20234

July 1983

U S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

NBSIR 83-2763

ARTIFICIAL TRAFFIC GENERATION OF

ISO TRANSPORT CLASS IV PROTOCOL

DATA UNITS ON AN IEEE 802.3

10 MEGABIT CSMA/CD LOCAL

AREA NETWORK

Timothy Gardner

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Institute for Computer Sciences and Technology

Systems and Network Architecture Division

Washington, DC 20234

July 1 983

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS. Ernest Ambler, Director

Table of Contents

1 .

2 .

3.

4.

5.

Abstract

Introduction

TGS Overview

Program Descriptions

4.1 Filter

4.2 Command

4.3 Simgen

4.4 Interp

4.5 Convert

4 . 6 Tlook

File Descriptions

5.1 Eglogs

5.2 Comfiles

5.3 Scenarios

5.4 Simfiles

5.4. Asciiscens ..

Page

1

2

3

6

6

6

10

11

12

12

13

13

13

14

14

Appendix 1

Artificial Traffic Generation 16

References 18

1 Abstract

The National Bureau of Standards' Institute for

Computer Sciences and Technology (ICST) is testing the

International Organization for Standardization's (ISO)

Transport Class IV protocol on an Institute of Electrical

and Electronics Engineers (IEEE) 802.3 Local Area Network.

Part of the test facility includes an artificial traffic

generator that produces ISO Transport Class IV protocol data

units encapsulated in IEEE 802.2 Type 1 Class 1 Logical Link

frames. The traffic generator submits the frames to the

network for transmission. This document describes the

architecture and usage of the traffic generator for multihost and multi- connection traffic.

Keywords: computer networks; CSMA/CD; local area networks;

traffic generation; standards; transport protocols

1
2 . Introduction

The National Bureau of Standards' Institute for

Computer Sciences and Technology (ICST) prepared

specifications and produced an implementation of the

International Organization for Standardization's (ISO)

Transport Class IV Protocol. At the request of a number of

companies, ICST held a series of workshops [1,2] for local

network vendors interested in implementing and testing these

specifications [3]. In conjunction with this effort, a multi- vendor demonstration of ISO Transport operating on a local area network conforming to IEEE 802.3 Local Area

Networking specifications [4] is expected in the 1984 time

f rame

.

ICST is developing several protocol test tools

including tools that test the correctness of the Transport

protocol implementation [5,6,7] and performance measurement

tools designed to assist in the testing, tuning and

debugging of vendor implementations. This document

discusses the traffic generator used by the performance

measurement tool now under construction.

This new tool (see figure 1) consists of a data

acquisition system, a real-time measurement facility and an

analysis and display software subsystem. These components

interconnect and attach to an IEEE 802.3 CSMA/CD local area

network. The data acquisition system captures Transport,

Network, and Link protocol data units from the network and

passes protocol header information to the real-time

measurement subsystem. The real- time measurement facility

tracks the transport protocol's finite state machine and

produces measures related to aggregate, link, and transport

traffic, host to host traffic, and connection traffic.

These measures are passed on to the analysis and display

subsystem where they are analyzed and displayed, providing

vendors and users with applicable tables, histograms, pie

charts, and other graphical aids for determining the

performance and for tuning the transport protocol.

This document provides a detailed description of the

traffic generation system (TGS) used by ICST to test the

above mentioned protocol test tool. Section 3 gives a general overview followed by two sections that descibe each

of the individual components of the system. Appendix 1

explains how to use TGS to generate traffic. It is intended

as a user's guide for those with access to the actual

system

.

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3. TGS Overview

The traffic generation system described by this report

is a system designed to create, edit, store, interpret, and

transmit IEEE 802.2 [8] link frames containing ISO transport

class IV protocol data units (TPDUs) as data. The generator

is capable of producing protocol data units containing any

destination or source link address and any set of transport

destination and source reference numbers. In addition, the

generator optionally creates "blocked" TPDUs, i.e. multiple

TPDUs encapsulated in one IEEE 802.2 Logical Link frame.

TGS generates flexible traffic useful in the testing and

tuning of programs using traffic from an 802.3 local area

network by allowing a user to control the flow and the

content of the traffic being created.

The TPDUs used by TGS for creating artificial traffic

are created by an exception generator which is part of the

correctness testing tools mentioned above [5]. This

exception generator creates "correct" transport protocol and

stores a log of the TPDUs in files called eglogs. TGS

modifies the destination and source reference numbers in

each TPDU and generates Link source and destination

addresses thus creating multi-connection and multi- host

network traffic.

TGS consists of a group of programs and a group of data

files where the programs store and retrieve data. The two

principle programs in the system are the Command Pile Editor

and the Traffic Simulator/Generator. The Command Pile

Editor is responsible for creating the set of commands that

the Traffic Simulator uses to create the "traffic

environment", i.e. the set of connections, the connection

entities, and the contents of each connection. The Traffic

Generator then transmits packets from this environment to

the local area network. The remaining programs in the

system are utility and support programs that make the system

more versatile.

The following gives a brief description of each program

and group of data files in TGS. Refer to figure 2 while

reading the descriptions to better understand the

architecture of the Traffic Generation System.

3
TGS consists of the following programs and data files:

Programs:

Filter -

Command -

Simgen -

Interp -

Convert

Tlook -

removes non-transport material from

exception generator log files

(eglogs) . Input is binary eglogs.

Output is binary scenario files.

menu driven program that assists

user in developing commands to run

the traffic simulator. Input is

user responses to prompts, the ascii

scenario directory file

"scenarios", and existing binary

command files. Output is binary

command files.

menu driven program that assists

user in creating traffic simulations

and in generating network traffic

from these simulations. Input is

user responses to prompts, binary

command files, files in the

scenarios file block, and binary

simulation files. Output is binary

simulation files and network

traffic.

creates an ascii interpretation of

simulation files for the purpose of

debugging TGS and the analysis

programs that use TGS traffic.

Input is binary simulation files.

Output is an ascii interpretation.

converts ascii interpretations of

scenario files created by Tlook back

into binary scenario files. Input

is ascii Tlook output. Output is

binary scenario files.

creates an ascii interpretation of

binary scenario files and eglogs.

This permits a user to modify

scenario files and convert the ascii

version back to binary using

Convert. Input is binary eglogs

and binary scenario files. Output

is ascii interpretations.
Data files:

eg logs -

|

Eglogs are created by the protocol

lab exception generator. An eglog

contains a group of TPDUs that make

up a transport scenario.

comfiles - binary command files that contain

traffic simulation commands. These

files are created by the command

file editor and are used to run

traffic simulations.

scenarios - this block contains binary scenario

files and an ascii directory file.

Scenario files are eglogs that have

have been filtered to remove nontransport material. The directory

file contains the name, reference

number, and description of every

scenario file. This file is

maintained by the user and updated

whenever a scenario file is added to

or deleted from the block. The

files in this block are used by

Simgen for the creation of traffic

simulations. The directory file

called "scenarios" is used by the

command file editor for creating and

editing command files.

simfiles - binary simulation files containing

output from the traffic simulator.

These files are also used by the

traffic generator for network

traffic generation.

asciiscens -- ascii interpretations of binary

scenario files. These files are

created by Tlook. Because these

files are ascii, a user may edit

them and then convert them back to

binary scenario files using Convert.

5
4. Program Descriptions

4.1 Filter

Filter removes

eglogs created by

transport material

exception generator

request TPDU of a stored in the same

of the event code in

different. Filter

containing an event

hexadecimal 16.

non-transport material from

the exception generator. Nonconsists of information the

outputs prior to the connect

connection. The material is

format as a TPDU , but the value

the header line (see 5.1) is

removes all material not

code of hexadecimal 6 or

The input to Filter is an eglog. The output

is a scenario file.

To run Filter; filter [eglog] [scenario file]

4.2 Command

Command is the command file editor used to

create and edit command files to drive the traffic

simulator (Simgen)

.

Input to Command is user responses to prompts,

command files, and the scenarios directory file.

Output from Command is command files, user prompts,

and user information.

To run Command: command

The screen displayed when the program is run is

the start menu. The user is prompted for one of

the following three commands.

c - create command file

e - edit existing command file

q - quit program

The following describes the above commands.

c - Command prompts the user for a file name. If

the file entered already exists. Command

notifies the user that it can not overwrite

existing files and the user is prompted for one

of the three commands. If the file does not

exist the editor menu is displayed.

6
Figure

2.

Overview

of

the

Traffic

Generation

System
^ J.

n
e - Command prompts the user for the name of an

existing command file. If the file cannot be

opened. Command notifies the user that it can

not open the file and the user is prompted for

one of the three commands. If the file is

opened without error, the editor menu is

displayed

.

q

- the program terminates.

If any other response is entered. Command notifies

the user that an illegal response has been entered

and prompts for a command.

After a legal file name has been entered.

Command displays the following editor menu and

header lines:

e - exit editor

s - list scenario files

c - list command file

d - delete a connection

i - insert a connection

r - refresh display

connection scenario connection between connection packet

number file # host # and host # repeats blocking

If the editor is in edit existing command file mode,

the chosen command file is listed under the header

lines

.

The last line of the screen contains the prompt

line: "Enter connection number to edit or CR for

next connection".

At this time the user may enter any one of the menu

commands When prompted for any other response, only

commands "e", "s", or "c" may be entered. If

command "d", "i", or "r" is entered when prompted

for anything other than a conection number. Command

notifies the user that the chosen command can only

be executed when prompted for a connection number.

Description of menu commands:

e - the command file is written and the start menu is

displayed

.

s - the scenario file menu is displayed.

7
The scenario file menu contains the

following commands:

m - return to main menu

1 - list scenario files

c - continue listing

Description of scenario file commands:

m - the user is returned to the editor.

1 - a descriptive listing of all scenario files

is listed.

c - the next page of scenario files is listed

if another page exists. If no additional

pages exist, the user is notified that the

listing is complete.

1 - the list command file menu is displayed.

The list command file menu is

identical to the list scenario files menu

and functions in the same manner except

that instead of listing scenarios, the

command file being edited is listed. This

menu allows a user to view prevous pages of

the command file if they exist.

d - Command prompts the user for a connection number

to delete. If an existing connection number is

entered, the connection is deleted; otherwise

the user is notified that the entered connection

cannot be deleted.

i - Command prompts the user for the number of the

connection the new connection is to be inserted

above. If an existing connection number is

entered, the user is prompted for the scenario

file number of the new connection; otherwise,

the user is notified that a connection cannot be

inserted

.

r - the display is refreshed showing only the

current status of each connection.

If just a carriage return is entered. Command prints

the number of the next connection to be formed and

prompts the user for a scenario file number.

8
If the number of an existing connection is entered,

the information about the connection is displayed

and the user is prompted for the scenario file

number

.

If an illegal command or the number of a nonexistant

connection is entered, the user is notified of an

illegal response.

After entering a carriage return (CR) , an

existing connection number, or inserting a new

connection, the user is prompted for a scenario file

number. A list of available scenario file numbers

is seen by entering the "s" command, a user is not

limited to the scenario numbers listed by the "s"

command though. If the connection is being edited,

a CR may be entered to continue on to the next

prompt without changing the displayed value. This

is true for all prompts after the connection number

prompt.

The next two prompts are for the number of the

host initiating the connection and for the host

receiving the connection. Host numbers are only

reference numbers that are mapped into network

addresses by the traffic simulator. A host number

is limited to integers between 1 and 6 inclusive.

An illegal response message is displayed if a number

greater than 6 or less than 1 is entered.

Connection repeats indicate to the traffic

simulator how many times to repeat the connection

upon termination. If an is entered the

connection will repeat forever.

Packet blocking indicates whether or not TPDUs

from the connection may be blocked together or with

TPDUs from other connections. The user should enter

a "y", or a "n" as a response to this prompt.

After a legal response is entered for the

packet blocking prompt, the connection number prompt

is once again displayed.

9
4.3 Simgen

Siregen is the traffic simulator and generator

used for creating traffic simulations and generating

network traffic.

Input to Simgen is user responses, command

files, scenario files, the scenario block directory

file, and simulation files. Output is user prompts,

user information, simulation files, and network

traffic

.

To run Simgen: simgen

Simgen contains only the following menu that is

displayed when the program is run:

c - create a traffic simulation

t - run traffic generator from existing

simulation file

x - change network addresses of hosts

q - quit program

Description of menu commands:

c - the user is prompted for a command file. If the

command file cannot be opened, the user is

notified and prompted for a command. If the

command file is opened successfully, the user is

prompted for a simulation file. If a CR is

entered, the simulator output is not sent to a

simulation file. This option is useful when

using command files that contain repeat forever

connections. If the simulation file entered

already exists, the user is notified that Simgen

cannot overwrite existing simulation files and

prompted for another simulation file.

After a legal response to the simulation

file prompt, the user is asked if the output

should be sent to the network. If a "y" is

entered Simgen tries to open the network

interface. If an error occurs, the simulation

is aborted and the user is prompted for a command. Otherwise, the simulation is started.

If at anytime during the simulation an

error is found in the command file or elsewhere,

the user is prompted for instructions. A user

may chose to abort the simulation or continue

the simulation without the connection causing

the error. The user is notified upon the

successful completion of the simulation.

10
t - the user is prompted for a simulation file. If

the simulation file cannot be opened, the user

is notified and prompted for a command. After a

legal simulation file is entered, Simgen tries

to open the network interface. If an error

occurs, the user is notified and prompted for a

command. Otherwise, the traffic generation is

started and the user is notified upon

completion.

x - a list of the default or current network

addresses is displayed. If the user enters a

CR, the address is not changed and the prompt

moves to the next address. If an illegal

address is entered the user is notified that an

illegal address has been entered and once again

prompted for an address. After a legal response

for the last address has been entered, the user

is prompted for one of the menu commands.

q

- Simgen is terminated.

4.4 Interp

Interp creates ascii interpretations of binary

simulation files. These interpretations are useful

for debugging TGS and for verification of the

network traffic generated to test other programs

using TGS traffic.

Input to Interp is simulation files. Output is

an ascii interpretation outputted to standard

output.

To run Interp: interp [simulation file]

If an error occurs trying to open the simulation

file, Interp notifies the user and terminates.

11
4.6 Convert

Convert converts asciiscens files back into

binary scenario files.

Input to Convert is asciiscens files. Output

is scenario files.

To run Convert: convert [asciiscens file]

[scenario file]

If an existing scenario file is given as the

scenario file argument. Convert notifies the user

that it cannot overwrite existing scenario files and

terminates. If an error occurs trying to open the

asciiscens file. Convert notifies the user and

termina tes

.

4.5 Tlook

Tlook creates ascii interpretations of binary

scenario files. These files may then be edited to

control the content of the traffic being generated.

Tlook may also be used to create ascii

interpretations of eglogs.

Input to Tlook is scenario files or eglogs.

Output is an asciiscens file.

To run Tlook: tlook [scenario file or eglog]

[asciiscens file]

If the asciiscens file argument is not given, output

is to the terminal. If an existing asciiscens file

is given as the asciiscens file argument Tlook

notifies the user that it cannot overwrite existing

asciiscens files and terminates. If an error occurs

trying to open the scenario file, Tlook notifies

the user and terminates.

12
File Descriptions

5.1 Eglogs

Eg logs are created by the Network Protocol

Group exception generator and are used as input by

Filter and Tlook.

Binary eglog format:

byte field field description

1 +0 tsize (0) tsize (1) total size of record

+2 acode (0) acode (1) exception generator code 4 secs (0) secs (1) time tag seconds

+6 secs (2) secs (3)

+8 msecs (0) msecs (1) timetag milliseconds

+10 head (0) head (1) eg header 12 bytes

• • • header bytes

+ 20 head (10) ecode (11) event code - part of header

+22 TPDU (0) TPDU (1) TPDU tsize - 22 bytes

• TPDUs

+tsize TPDU fill fill exists if tsize is odd

5.2 Comfiles

Comfiles are created by Command and are used as

input to Command and Simgen.

Binary comfile format:

byte field

+0 sf num(0) sf num (1)

+2 hostl (0) hostl (1) + 4 host2 (0) host2 (1)

+6 reps (0) reps (1)

+8 blkg (0) blkg (1)

field description

scenario file number

initiating host number

receiving host number

connection repeats

TPDU blocking

- 13 -

i
5.3 Scenarios

This group of data files consists of an ascii

directory file containing a description of each of

the scenario files and the binary scenario files.

The ascii directory file is created by the TGS

user and is used as input by Command and Siragen.

Ascii directory file format:

lumn to column field

1 6 blank

7 16 name

17 36 number

37 48 numTPDUs

49 £OLN descrp

Scenarios are created

Singen and Tlook.

field description

blank

scenario file name

scenario file number

number of TPDUs in file

file description

by Filter and are used by

Binary scenarios format:

same as format of binary eglogs

5.4 Simfiles

Simfiles are created by Simgen and are used by

Simgen and Interp.

Binary simfile format:

byte field field description

+ 0 len (0) len (1) total record length

+2 daddr (0) daddr (1) network destination address

+ 4 daddr (2) daddr (3)

+6 daddr (4) daddr (5) + 8 saddr (0) saddr (1) network source address

+10 saddr (2) saddr (3) + 12 saddr ( 4

)

saddr (5)

+14 lgth (0) lgth (1) 802 length

+ 16 Ctrl (0) net (1) control and network

+ 18 TPDU (0) TPDU (1) TPDUs

• +len TPDU filler filler if len is odd

14
5.5 Asciiscens

Asciiscens are created by Tlook and are used as

input by Convert.

Ascii asciiscens format:

column to column field field description

line 1 1 10 time tag hour s:min: sec . tenths

11 11 blank blank

12 19 (size * ascii characters

20 21 or 22 size TPDU size including header

22 or 23 30 or 31 , code = ascii characters

31 or 32 31 or 32 code exception generator code

32 or 33 32 or 33 ) ascii character

line 2 1 3 header hex header byte

4 6 header hex header byte

28 30 header hex header byte

line 3 1 3 header hex header byte

4 7 header hex header byte

8 10 TPDU hex TPDU byte

11 14 TPDU hex TPDU byte

Lines continue in same format with 10 pairs of TPDU

bytes per line until the end of the TPDU. TPDU

pairs are separated by 2

are separated by 1 blank.

blanks

;

TPDUs in a pair

Records are separated by a blank line

.

15
Appendix 1

Artificial Traffic Generation

The first step in using TGS to generate traffic

is obtaining an eglog. Use the following steps to

obtain an eglog:

1. Login to the Protocol Laboratory computer.

2. Select scenario to be used to create eglog.

A listing of eg scenarios is in

/u2/night/phase2/testdoc/g .appl.

Each scenario has 2 files associated with

it. These files reside in /u2/night/phase2

/newrt and /u2/night/phase2/newtc . Copy

the rt version and the tc version to the

user directory.

4. In rt version of the file, change the

first 2 numbers of the first non-commen ted

line from 1 2 to 2 1.

5. Enter the following commands:

tstart -el

next 0 /u2/gardner/tgs

next 0 tc_scenario name

next 1 rt_scenario name

6. An eglog now exists in a file called

eg. log. Move this file into the tgs/eglogs

directory on the system containing TGS

using available FTP programs.

A much more detailed explaination is found in [5]

.

The next step is to filter the eglog to create

a scenario file. This step is explained in 4.1.

Since a new scenario file has been added, the

scenarios directory file must be updated. This is

done by editing tgs/scenar ios/scenarios and adding

the information about the new scenario file

following the format in 5.3.

Now run tgs/programs/command to create a command file. A detailed explaination of how to run

Command is found in 4.2.

Run tgs/prog rams/s imgen as explained in 4.3.

This is the final step in creating network traffic.

16
The traffic created by Simgen may be

interpreted if Simgen was run in the create

simulation file mode. To interpret the simulation

file, run tgs/prog rams/in terp according to the

instructions in 4.4.

To change a scenario file, run

tgs/utili ty/tlook according to 4.5. The asciiscens

file created will reside in tgs/asciiscens and may

now be edited. When editing is complete, convert

the asciiscens file back into a scenario file using

tgs/utili ty/convert. An explaination of how to run

this program is found in 4.6. Once again, the

scenarios directory file must be update since a

scenario file was changed or added.

A copy of this documentation resides in the

tg s/docs directory and the source code of all

programs reside in tgs/source.
References

[1] Proceedings of the First LAN-Transport Workshop. Nat.

Bur. Stand. (U.S.) NBSIR 83-2673; 1983 February.

[2] Proceedings of the Second LAN-Transport Workshop.

Nat. Bur. Stand. (U.S.) NBSIR 83-2717; 1983 March.

[3] Proposed Federal Information Processing Standard,

Specifications of a Transport Protocol for Computer

Communications, Volumes 1-6. Nat. Bur. Stand.

I CST/HLNP 83-1 - ICST/HLNP 83-6; 1983 February.

[4] Draft IEEE Standard 802.3 CSMA/CD Access Method and

Physical Layer Specifications. Institute of

Electricial and Electronic Engineers. 1982 December.

[5] Nightingale, J. Stephen. Users Guide to the Testing

System for Implementations of the ICST Transport

Protocol. Nat. Bur. Stand. ICST/SNA 2; 1983 July.

[6] Nightingale, J. Stephen. A Test Suite for

Implementations of the ICST Transport Protocol. Nat.

Bur. Stand. ICST/SNA 3; 1983 July.

[7] Nightingale, J. Stephen. Specifications of a Remote

Scenario Interpreter for Implementations of the ICST

Transport Protocol. Nat. Bur. Stand. ICST/SNA 3; 1983

J uly

.

[8] Draft IEEE Standard 802.2 Logical Link Control.

Institute of Electrical and Electronic Engineers.

1982 November.

- 18 -

2 51
NBS-114A (REV. 2-80

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

NBSIR 83-2763

2. Performing Organ. Report No. 3. Publication Date

August 1983

4. TITLE AND SUBTITLE

Artificial Traffic Generation of ISO Transport Class IV Protocol Data Units

on an IEEE 802.3 10 Megabit CSMA/CD Local Area Network.

5. AUTHOR(S)

Timothy J. Gardner

6. PERFORMING ORGANIZATION (If joint or other than N8S. see instructions)

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No.

8. Type of Report & Period Covered

9.

SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street, City. State. ZIP)

10.

SUPPLEMENTARY NOTES

: J Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most si gnifi cant information. If document includes a significant

bibliography or literature survey, mention it here)

The National Bureau of Standards' Institute for Computer Sciences and Technology

( ICST) is testing the International Organization for Standardization's (ISO)

Transport Class IV protocol on an Institute of Electrical and Electronics

Engineers (IEEE) 802.3 Local Area Network. Part of the test facility includes

an artificial traffic generator that produces ISO Transport Class IV protocol

data units encapsulated in IEEE 802.2 Type 1 Class 1 Logical Link frames.

The traffic generator submits the frames to the network for transmission. This

document describes the architecture and usage of the traffic generator for

multi-host and mul ti -connection traffic.

12.

KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

computer networks; CSMA/CE; local area networks; standards; traffic generation;

transport protocols

13. AVAILABILITY

XpOnl i mi ted

| | For Official Distribution. Do Not Release to NTIS

[~n Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402.

Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

,21 Tr

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$7.00

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