Debugging

Presentation Title Subtitle

Author

OPNET Technologies, Inc.

Copyright © 2000 OPNET Technologies, Inc.

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TM OPNET UNIVERSITY

2000

Debugging Simulation Models --Introduction


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OPNET UNIVERSITY

2000

Debugging Simulation Models Intro 2

Goals

•Develop a sensible approach to debugging

•Teach use of OPNET Debugger (ODB)

• How to debug models

• Review features and commands

•Discuss the debugging process

• Step-by step methods for debugging models


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OPNET UNIVERSITY

2000


Items Not Covered

•Will not cover…

• C programming

• Segmentation violation

• Bus error

• These topics are covered in the session Debugging Simulation Models – Advanced.


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OPNET UNIVERSITY

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Prerequisites

• Familiarity with

• OPNET Modeler model hierarchy

• Creating process models

• Running simulations


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OPNET UNIVERSITY

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Agenda

• Interpreting error messages

• Identifying the problem

•Using the OPNET Debugger (ODB)

•Viewing animation for debugging


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The Challenge

• Debugging is like finding a needle in a haystack

• Narrow down the problem

• Time (event number)

• Space (code segment)

• Different types of problems

Structural Simulation fails to execute successfully.

Illustrated in Lab 1

Behavioral Simulation completes successfully, but does not accurately represent the modeler‟s intent.

Illustrated in Lab 2


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Object Reference

• Objects can be identified in two ways

• Object ID: Unique integer identifying object

• Object Name: Hierarchical name of object:

Format: <subnet name(s)>.<node name>.<module name>

top.e_campus.bldg_10.router.in_queue

<subnet name(s)> top.e_campus.bldg_10

<node name> router

<module name> in_queue


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OPNET UNIVERSITY

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Simulation Log

• Records notable events for every scenario

• Recreated every time a scenario‟s simulation is run

• Describes problems

• Suggests solutions

• Gives informational messages


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OPNET UNIVERSITY

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Simulation Error Classifications

Program Abort

Problem that prohibits the simulation from proceeding.

Recoverable Error

Problem that does not prohibit the simulation from proceeding, but may result in cancellation of the current operation.

Diagnostic Error

Problem that is recoverable, but minor.

Only reported if the diag_enable preference is TRUE. Default value is FALSE.

Warning Message typically generated by model to identify problems within the model itself, written by model developer using op_sim_message() Kernel Procedure (KP).


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OPNET UNIVERSITY

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Error Message Fields

|----------------------------------------------------------------------------|

| <<< Recoverable Error >>> |

| Output stream index (1) is out-of-range. |

| T (21.4), EV (254), MOD (top.sample_net.stn_5.mac), KP (op_pk_send) |

|----------------------------------------------------------------------------|

Type Type of error

T Simulation time of error

EV Event ID of simulation event

MOD Name of module where error occurred

KP Name of Kernel Procedure that reported the problem

Messages Match in Kernel Procedure docs


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Obtaining a Function Call Stack (FCS)

• Function call stack provides the user with

• More details

• Locates error in space

• Contains function listings

•err_log file in <home>/op_admin records all FCSs

• This file will grow over time and may be periodically removed

•op_vuerr utility extracts last FCS from err_log

•-num_err attribute can be used to extract the last N errors in case the error of interest is not the most recent

• Example: op_vuerr -num_err 5


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OPNET UNIVERSITY

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Example Function Call Stack

<<< Program Abort >>>

. . .

* Function call stack: (builds down)

------------------------------------------------------------

Call Block

Count Line# Function

------------------------------------------------------------

0) 1 125 m3_main (argc, argv)

1) 1 519 sim_main (prog_name, argc, argv, dynamic, ...)

2) 1 935 sim_ev_loop ()

3) 1 79 sim_strm_insert ()

4) 6 477 sim_obj_qps_intrpt (simev_ptr)

5) 5 0 pksw_nd_proc () [xmt enter execs]

6) 1 60 op_pk_nfd_set (pkptr, fd_name, value, <...>)

............................................................

7) 1 1481 *sim_err_pk_access (pkptr, error_code)

8) 1 88 *sim_err_issue (pkg_id, msg_id, <subst_values>)

9) 1 339 sim_err_print (severity_level, str0, str1)

------------------------------------------------------------

Sim.

Kernel

Error

Message

Printing

Process model

and state

KP reporting

problem


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OPNET UNIVERSITY

2000


Block Line Numbers in FCS

• Block Line Numbers refer to last curly brace passed 1 int function(void)

2 {

3 int x, z;

4

5 FIN (function (void))

6 z = 0; A

7 for (x = 0; x < 10; x++)

8 {

9 printf (“z = %d\n”,z);

10 z += x; B

11 }

12 FRET (z) C

13 }

• Location A Reported block line number: 5

• Location B Reported block line number: 8

• Location C Reported block line number: 11


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Development and Optimized Kernels

• OPNET includes two different Simulation Kernels:

• Optimized Kernel

Run simulations, collect statistics

Faster

• Development Kernel

Same features as Optimized Kernel…

Plus diagnostic information automatically collected

Slower

• Development Kernel must be used for most debugging activities

• In order to see complete FCS, the process models and external files must be compiled with comp_trace_info


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Using the Development Kernel

•The kernel_type preference

• Controls which Simulation Kernel is used during a simulation

•To set kernel_type to development: • Don‟t use optimize_simulation environment file

• Command line: op_runsim -kernel_type development

• Preferences: set kernel_type to development

• Set comp_trace_info environment attribute to TRUE

• This inserts additional trace information into compiled code

• Use FIN/FOUT/FRET macros in custom functions


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OPNET UNIVERSITY

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OPNET Debugger (ODB)

• ODB capabilities

• Allows you to gain interactive control of the simulation

• You can issue commands to obtain detailed information about events or objects of interest

• The same events are executed in debug and non-debug sims


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ODB Features

• ODB provides commands that allow user to:

• Execute single and multiple events

• Set breakpoints for specific events, times, modules, and processes

• Trace Kernel Procedures as they are being executed

• Print out information about the current status of simulation entities

• Print out statistics of memory usage

• Affect the course of the simulation by modifying object attributes


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OPNET UNIVERSITY

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How to Activate / Invoke ODB

• Use the debug environment attribute to activate ODB

• To set the value of debug :

• From the Simulation Tool:

Include debug environment file

• From the command line:

Example use:

op_runsim -net_name project1-scenario1 -debug


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Invoking and Exiting ODB

• Commands can be issued at odb> prompt

• To end the simulation:

•quit - terminates the simulation normally (creates output files)

•exit - immediately exits ODB, no output file created

% op_runsim -net_name example -debug

<...simulation banner...>

______________ OPNET Simulation Debugger ____________

Type „help‟ for Command Summary

odb> Time 0, before begsim interrupts are delivered


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Getting Help in ODB

•help command is available at odb> prompt

•help: displays summary of help categories

•help <category>: displays help on specified category

•help <command>: displays help on specified command

odb> help

________________ OPNET Debugger Help ________________

There are three levels of help:

help -- displays summary of help categories.

help <category> -- display help on specified category.

help <command> -- display help on specified command.

____ Command Categories [builtin] ____

all

basic

action

...


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ODB: Lesson Plan • Breakpoints

• Traces

• Labels

• Lab 1

• Break

• Maps

• Entity Information

• Lab 2

• Diagnostic Block

• Memory Allocation


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OPNET UNIVERSITY

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Breakpoints • Interrupt simulation execution

• Allow the user to issue commands at the odb> prompt

• Two methods of advancing simulation execution within ODB:

• Single event execution

• Continuation of event

execution until

a breakpoint occurs

00:21

00:05

00:31

00:45

00:51

Single Event Execution

00:21

00:05

00:31

00:45

00:51

Multiple Event Execution

cont

pending

breakpoint

next

set breakpoint

00:59

next

next

next

next

set breakpoint

set breakpoint

set breakpoint

set breakpoint


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OPNET UNIVERSITY

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Breakpoints: cont and next

•next - executes one event and stops before the next event

•cont - continues simulation execution until a pending breakpoint

• May be equivalent to several „next‟ commands

00:21

00:05

00:31

00:45

00:51

Single Event Execution

00:21

00:05

00:31

00:45

00:51

Multiple Event Execution

cont

pending

breakpoint

next

set breakpoint

00:59

next

next

next

next

set breakpoint

set breakpoint

set breakpoint

set breakpoint


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OPNET UNIVERSITY

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Breakpoints: Interpreting the Event Banner

• At each breakpoint, event banner for next pending event is displayed

____________________________ (ODB 7.0.B: Event) ____________________________

* Time : 9.08349170694 sec, [00d 00h 00m 09s . 083ms 491us 706ns 942ps]

* Event : execution ID (10), schedule ID (#20), type (stream intrpt)

* Source : execution ID (9), top.pksw1.node_0.src (ideal generator)

* Data : instrm (1), packet ID (1)

> Module : top.pksw1.node_0.proc (processor)

•Time Simulation time associated with the event

•Event Event ID associated with the event

•Type Type of interrupt that will be delivered

•Source Module generating the interrupt

•Data Other information associated with the event

•Module Simulation object where the event will occur


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OPNET UNIVERSITY

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Breakpoints: Basic Commands

next

Execute the next pending event and set a breakpoint after its completion

evstop For specified pending event

tstop For specified time

mstop For all interrupts delivered to a specific module

prostop When a specified process is about to be invoked

intstop For a specified module and type of interrupt


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Breakpoints: Reviewing

•status command displays all pending breakpoints

odb> evstop 34

odb> tstop 40

odb> status

Breakpoints :

1) stop at event (34)

2) stop at time = (40) sec.

Traces :

None


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Breakpoints: Deleting and Suspending

• Breakpoints may be deleted while still pending

• Command: delstop

• Breakpoints may be suspended, then re-activated so that complete recreation is not necessary

• Command: suspstop

• Command: actstop


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Traces

• A list of KPs called by a process

• Used to print detailed information about event execution

• Typical traces display details of Kernel Procedures

• KP name

• Argument names

• Argument values

• Return value

• Contain information about the process being executed

• Once activated, a trace remains active until deactivated


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OPNET UNIVERSITY

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Traces: Interpretation

* invoking process (“pk_sink”)

__________state (st_0): exit executives__________

* op_intrpt_strm ()

active strm (0)

* op_pk_get (instrm_index)

strm. index (0)

packet ID (1)

* op_pk_destroy (pkptr)

packet ID (1)

__________state (st_1): enter executives_________

*returning from process (“pk_sink”)

Process invocation

Process return

State banner

KP invocations

State banner


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OPNET UNIVERSITY

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Traces: Interpreting KP Trace Format

• Kernel Procedure invocation argument values

• Kernel Procedure return values


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OPNET UNIVERSITY

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Traces: Basic Commands

fulltrace Global tracing of all KP invocations. Toggles between enabled or disabled

mtrace KPs invoked within a specified module

protrace KPs invoked within a specified module process

pktrace KPs which affect a certain packet

pttrace KPs which affect a certain packet tree


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odb> pktrace 5

odb> mtrace 11

odb> protrace 0

odb> status

Breakpoints :

None

Traces :

0) trace on packet with ID (5) (packet not in system)

1) trace on module (top.pksw1.node_0.proc)

2) trace on process (0)

Traces: Reviewing

•status command displays all pending traces


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OPNET UNIVERSITY

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Traces: Suspending and Deleting

• Traces may be deleted

• Command: deltrace

• Trace may be suspended, then re-activated so that complete recreation is not necessary

• Command: susptrace

• Command: acttrace

• If fulltrace is active, fulltrace again toggles to inactive


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Labels

• Established by process model code

• Allow traces restricted to classes of activity

• Print values of state, temporary variables

• Print results of statements

• User-defined trace statements may be added to a process model

• Many OPNET standard models use labels

• e.g. TCP, ATM


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Labels: Basic Commands

•ltrace

• Sets a trace for a specified label

• Example: ltrace atm

•mltrace

• Sets a trace for a specified module and label

•proltrace

• Sets a trace for a specified process model and label


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____________________________ (ODB 7.0.B: Event) ____________________________


* Event : execution ID (15204), schedule ID (#15605), type (remote intrpt)

* Source : execution ID (15203), top.Office network.DEVELOPMENT.tcp (processor)

* Data : code (10)

> Module : top.Office network.DEVELOPMENT.tcp (processor)

| Removing connection (14) from TCB list.

/* Print trace information if enabled */

if (op_prg_odb_ltrace_active (“tcp”))

{

sprintf (msg0, “Removing connection (%d) from TCB list.”, conn_id);

op_prg_odb_print_minor (msg0, OPC_NIL);

}

Labels: Example of a Labeled Trace

• User-defined code that checks for a label and prints the relevant information:

• Output when running a simulation with the TCP trace turned on (ltrace tcp):


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OPNET UNIVERSITY

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A Basic Debugging Paradigm

1. Locate the error

• From error message, identify event number of an error

2. Stop the simulation at the last event before the error

• In ODB, evstop with that event number

•cont to “skip ahead” to that event of interest

3. Turn on traces

•fulltrace to turn on detailed trace

•next to view execution details of the event of interest

4. Inspect the traces

5. Fix the problem


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OPNET UNIVERSITY

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Lab 1: Using evstop and fulltrace

• Context: Packet Switching Tutorial model

Packets are evenly routed between 4 nodes via a hub

• Open Project Editor and load pksw_net

• Open lab1 scenario

Scenario node_0 model hub model


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* Time: 20:28:15 Sun Aug 06 2000

* Program: op_runsim (Version 7.0.B PL6 Build 1086)

* Function: sim_err_print (severity_level, str0, str1)

* Error: Packet pointer is NIL

T (8.93569), EV (6), MOD (top.pksw1.node_1.proc),

KP (op_pk_nfd_set)

Lab 1: Error Message from pksw_net

1. Execute simulation from command line

op_runsim -net_name pksw_net-lab1

2. Inspect error message

3. Note: Event ID 6


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OPNET UNIVERSITY

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Lab 1: Obtain fulltrace Information

1. Execute simulation in debug mode op_runsim -net_name pksw_net-lab1 -debug

2. Set evstop for event 6 (evstop 6)

3. cont to continue until event 6

4. fulltrace to toggle global tracing

5. next to execute pending event

____________________________ (ODB 7.0.B: Event) ____________________________



* Source : execution ID (5), top.pksw1.node_1.src (ideal generator)


> Module : top.pksw1.node_1.proc (processor)

breakpoint trapped : "stop at event (6)"


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OPNET UNIVERSITY

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Lab 1: Inspect fulltrace Information _________THREAD 236: state (xmt): enter executives_________

* THREAD 236: op_pk_get (instrm_index)

THREAD 236: strm. index (0)

THREAD 236: strm. is empty.

* THREAD 236: op_dist_outcome (dist_ptr)

THREAD 236: dist. ptr. (0x00901EA8)

THREAD 236: distribution (uniform_int (0.000000000e+000, 3.0000000000e+000))

THREAD 236: outcome (1.0)


* Time: 20:44:52 Sun Aug 06 2000

* Program: op_runsim (Version 7.0.B PL6 Build 1086)

* Function: sim_err_print (severity_level, str0, str1)

* Error: Packet pointer is NIL

T (8.93569), EV (6), MOD (top.pksw1.node_1.proc), KP (op_pk_nfd_set)

6. Observe: packet arrived on stream 1, but op_pk_get() attempts to access stream 0

7. quit to quit ODB


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OPNET UNIVERSITY

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Lab 1: Correct the Error

1.In the Project Editor double click on

• Double-click on node_1 to edit module proc

• Double-click on module proc to edit process model pksw_nd_proc

2. Edit enter executive of xmt state

Change

pkptr = op_pk_get (RCV_IN_STRM)

to

pkptr = op_pk_get (SRC_IN_STRM)

3. Compile process model


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OPNET UNIVERSITY

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Lab 1: Confirm the Error is Corrected

prompt% op_runsim -net_name pksw_net-lab1

|-----------------------------------------------------------------------------|

| Module (11), (top.pksw1.node_0.proc) |

| From procedure: pksw_nd_proc1 () [end enter execs] |

| Node node_0: received 89 packets. |

|-----------------------------------------------------------------------------|

|-----------------------------------------------------------------------------|




|-----------------------------------------------------------------------------|

< . . . >

|-----------------------------------------------------------------------------|

| Simulation Completed - Collating Results. |

| Events: Total (1077), Average Speed (2761 events/sec.) |

| Time: Elapsed (1 sec.), Simulated (16 min. 40 sec.) |

|-----------------------------------------------------------------------------|


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Break


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OPNET UNIVERSITY

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Maps

• A list of simulation objects corresponding to some criteria

• Provides object IDs and corresponding topological “location”

• Objects are identified by name or object ID

• Inspect state of simulation objects and packets

• Typically:

• Selection of a specific object (RIP process at Router_4)

• Selection of all objects of a specific type (map of all queue objects in the simulation, packets from the same packet tree)


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OPNET UNIVERSITY

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odb> objmap proc hub

Obj ID Obj Name Obj Type Parent ID

-----------------------------------------------------------------------------------------

55 top.pksw1.hub.hub processor 6

Maps: Interpreting Command Output

Packet switching tutorial network:

•Obj ID: Unique integer identifying object

•Obj Name: Hierarchical name of object

•Obj Type: Description of class of object

•Parent ID: Object ID of parent object


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OPNET UNIVERSITY

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Maps: Basic Commands

objmap

List of objects matching specified criteria

promap List of processes associated with a specified processor or queue

objid Object id of a specified object

objassoc List of objects of the specified type that are associated with the specified object

pkmap List of packets matching specified criteria

ptmap List of packets belonging to a specified tree


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OPNET UNIVERSITY

2000


Entity Information

• Commands can be applied to objects to display verbose information about the state of the object

• Examples:

• Current state of a subqueue, including list of packets it contains

• Contents of packet fields


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OPNET UNIVERSITY

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Entity Information: Basic Commands

objprint Display information about an object -- attribute values, queue sizes and contents, process information.

pkprint Display information about a packet -- ID, field values, current location, size

attrget Display the current value of an attribute of an object

attrset Assign a new value to an attribute of an object

attrprint Display information about the internal state of a specified attribute


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Entity Information: Example

odb> pkprint 6937

* packet contents:

ID : 6937

format : ethernet

creation module : top.ethcoax_net.stn_8.mac

creation time : 5.32919

total size : 12208

owner : top.ethcoax_net.stn_8.mac

Index Name Type Value Size

0 preamble info unspecified 64

1 dst_addr integer 2 48

2 src_addr integer 6 48

3 type integer 0 16

4 data packet pk id (6936) 12000

5 last_sent_MAC_ID integer 148 0


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OPNET UNIVERSITY

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Entity Information: Obtaining

• Determine Object ID of object of interest

•objmap <type> to obtain a list of selected objects

or

• Visually identify object of interest from hierarchical names in map and find its object ID

• Print information about the object

• Use objprint <Obj ID>


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OPNET UNIVERSITY

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Lab 2: Using Entity Information

Problem: Unexpected simulation results: all packets are received by node_0

• The error may indicate a problem with setting destination address field in packets

• Use pkprint to investigate contents of packet fields


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OPNET UNIVERSITY

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Lab 2: Unexpected Results


|-----------------------------------------------------------------------------|




|-----------------------------------------------------------------------------|

|-----------------------------------------------------------------------------|




|-----------------------------------------------------------------------------|

< Other nodes also receive 0 packets>

|-----------------------------------------------------------------------------|




|-----------------------------------------------------------------------------|


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OPNET UNIVERSITY

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Lab 2: Approach -- Tracing One Packet

1. Execute simulation in debug mode

op_runsim -net_name pksw_net-lab1 -debug

2. Set pktrace for packet 0 (pktrace 0)

3. next until event involving packet 0 is encountered


* Event : execution ID (5), schedule ID (#10), type (self intrpt)

* Source : execution ID (-1), top.pksw1.node_1.src (ideal generator)

* Data : code (0)

> Module : top.pksw1.node_1.src (ideal generator)

odb> next

* THREAD 305: generating packet

THREAD 305: packet ID (0)

THREAD 305: bulk size (9600)

THREAD 305: total size (9600)


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OPNET UNIVERSITY

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odb> next




* THREAD 305: op_pk_nfd_set (pkptr, fd_name, value, <...>)


THREAD 305: field name (dest_address)

THREAD 305: field type (integer)

THREAD 305: field value (1)

THREAD 305: field size (0)

* THREAD 305: op_pk_send (pkptr, outstrm_index)


THREAD 305: stream index (0)

Lab 2: Tracing One Packet (continued)

4. next to observe a packet field being set


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OPNET UNIVERSITY

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odb> pkprint 0

* THREAD 305: packet contents:

THREAD 305: ID : 0

THREAD 305: tree ID : 0

THREAD 305: address : 0x8AAB90

THREAD 305: format : pksw_format

THREAD 305: creation module : top.pksw1.node_1.src

THREAD 305: creation time : 8.93569

THREAD 305: stamp module : top.pksw1.node_1.src

THREAD 305: stamp time : 8.93569

THREAD 305: bulk size : 9600

THREAD 305: total size : 9600

THREAD 305: owner : top.pksw1.node_1.strm_2

THREAD 305: ICI ID : NONE

THREAD 305: ID trace : on

THREAD 305: tree ID trace : off

THREAD 305: encap flags : NONE

Index Name Type Value Size

0 dest_address integer 1 0


5. pkprint to observe contents of packet fields


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6. next to continue tracing

7. Hub receives packet at event 15, stop the simulation at event 15

odb> evstop 15

odb> cont

. . .

____________________________ (ODB 7.0.B: Event) ____________________________



* Source : execution ID (14), top.pksw1.hub.rcv3 (pt-pt receiver)


> Module : top.pksw1.hub.hub (processor)

breakpoint trapped : "stop at event (15)"


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8. next to continue tracing

9. Observe further manipulation of packet

odb> next




* THREAD 305: op_pk_nfd_set (pkptr, fd_name, value, <...>)


THREAD 305: field name (dest_address)

THREAD 305: field type (integer)

THREAD 305: field value (0)

THREAD 305: field size (0)

* THREAD 305: op_pk_send (pkptr, outstrm_index)


THREAD 305: stream index (0)


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OPNET UNIVERSITY

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odb> pkprint

* THREAD 305: packet contents:

THREAD 305: ID : 0

THREAD 305: tree ID : 0

THREAD 305: address : 0x8AAB90

THREAD 305: format : pksw_format

THREAD 305: creation module : top.pksw1.node_1.src

THREAD 305: creation time : 8.93569

THREAD 305: stamp module : top.pksw1.node_1.src

THREAD 305: stamp time : 8.93569

THREAD 305: bulk size : 9600

THREAD 305: total size : 9600

THREAD 305: owner : top.pksw1.hub.strm_8

THREAD 305: ICI ID : NONE

THREAD 305: ID trace : on

THREAD 305: tree ID trace : off

THREAD 305: encap flags : NONE

THREAD 305: Index Name Type Value Size

THREAD 305: 0 dest_address integer 0 0


10. pkprint to observe contents of packet fields


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Lab 2: Localization of Error

• Observe: Value of packet field 0 has been changed to 0 from its originally set value of 1

• Packet is therefore sent on stream 0, not on stream 1 as expected

11. Exit debugger


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OPNET UNIVERSITY

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Lab 2: Correct the Error

1. In the project editor double click on

• node hub to see module hub

• module hub to edit process model pksw_hub_proc

2. Edit enter executive state route_pk

• Note that the destination address was never initialized

3. Change op_pk_nfd_set (pkptr, “dest_address”, dest_address);

to op_pk_nfd_get (pkptr, “dest_address”, &dest_address);

4. Compile process model


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Lab 2: Confirm the Error is Corrected


|-----------------------------------------------------------------------------|




|-----------------------------------------------------------------------------|

|-----------------------------------------------------------------------------|




|-----------------------------------------------------------------------------|

<Other nodes receive similar numbers of packets> |-----------------------------------------------------------------------------|




|-----------------------------------------------------------------------------|


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Diagnostic Block

• Process model code that may be invoked via an ODB command

• Statements that display state information of interest

• values of state variables

• Contents of key data structures (example TCP Transmission Control Block, routing tables)

• Diagnostic block may be invoked from any breakpoint

• Created in Process Editor

• Diagnostic block button


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Diagnostic Block: Example

• Code in Diagnostic block:

• Text in ODB:

op_prg_odb_print_major ("TCB list:", OPC_NIL);

list_size = op_prg_list_size (tcb_list);

for (i = 0; i < list_size; i++)

{

tcb_ptr = (TcpT_Tcb *) op_prg_list_access (tcb_list, i);

/* Print socket information. */

sprintf (msg0, "Connection (%d) information: state (%s)",

tcb_ptr->conn_id, tcb_ptr->state_name);

....

....

}

| TCB list:

| Connection (1) information: state (LISTEN)

| Application objid (26034), Type of Service: As Requested by Client,

| traffic through stream (1)


Title – 65



OPNET UNIVERSITY

2000


Diagnostic Block: Basic Commands

•prodiag: invokes the diagnostic block of a specified process

•proldiag: executes the diagnostic block of the specified process and sets a trace for a specified label restricted to the execution of the block

• Example: (Diagnostic block of ip_rte_v4.pr.m)

if (op_prg_odb_ltrace_active ("ip_frag"))

{

ip_frag_sup_print (dgram_list_ptr);

}


Title – 66



OPNET UNIVERSITY

2000


Diagnostic Block : How to Use

1. Find object ID of module containing the process of interest • Use objmap type to obtain a list of selected objects

Example: objmap proc rip gives the list of all rip modules

• Locate desired node and note module ID of interest

2. Find object ID of the process of interest • Use promap objid where objid is the module of interest

Example: promap 104

3. Run the simulation in debug mode; stop it at some time

4. Print the information from the diagnostic block Example: proldiag 0 rip_route_table


Title – 67



OPNET UNIVERSITY

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Memory

• Simulation Kernel tracks memory allocation

• organized by source categories

• Display of memory categories

• Identify areas of memory buildup

• Example: Packets received but never destroyed

• Memory Usage Monitor object

• Located in utilities object palette


Title – 68



OPNET UNIVERSITY

2000


Memory: Commands

•memstats

• Displays a list of statistics for memory categories

• High-level

• Can be limited to categories accounting for more than a specified amount of memory

• Advanced:

•memsrc: Displays list of allocation sources for a memory category

•memsnk: Displays list of deallocation sinks for a memory category


Title – 69



OPNET UNIVERSITY

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odb> memstats 10

--------------------------------------------------------------------------------

Object Allocation Statistics

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

Memory Category Bytes #Use #Free #Total Total(KB)

--------------------------------------------------------------------------------

general - - - - 308

linked list cell 12 43405 4 44000 516

linked list cell [long] 12 249 0 1000 12

linked list cell [short] 12 0 143 1000 12

linked list desc. 24 70 436 550 13

--------------------------------------------------------------------------------

obj attribute props 176 67 - 67 13

other - - - - 72

packet 136 36153 0 37001 4915

packet field block (pksw_format) 24 36154 0 36201 849

process descriptor 152 5 0 1001 149

--------------------------------------------------------------------------------

……………..

--------------------------------------------------------------------------------

Total (KB) 15299

Memory: memstats Output

Model: Packet switching tutorial run for 100 hours without destroying packets


Title – 70



OPNET UNIVERSITY

2000


Memory: Identifying Memory Buildup

• Use memstats at some time T

• Use tstop T + T for some future time

• Use memstats

• Compare

• Repeat to identify areas of buildup


Title – 71



OPNET UNIVERSITY

2000


Animation as a Debugging Technique

• Animation can be used to visualize the behavior of a simulation

• Can help identify location on which to focus in ODB

• Demo: Visualizing a failure in packet routing


Title – 72



OPNET UNIVERSITY

2000


Summary

• Determine the nature of the problem first

• Simulation Log

• err_log, op_vuerr

• ODB allows interactive control over a simulation to investigate its behavior

• Set breakpoints, traces, query object information, print information from diagnostic blocks

• Key commands:

•help

•evstop, tstop, mstop

•next, cont

•fulltrace, mtrace, pktrace

•pkmap, objmap

•pkprint, objprint


Title – 73



OPNET UNIVERSITY

2000


Reference

• All ODB documentation • Simx chapter of External Interfaces Manual • OPNET Simulation Debugger section

• General ODB Concepts

• ODB Concepts

• ODB Command Reference • ODB Command Reference

• ODB Tutorial

• ODB Usage Scenarios


Title – 74



OPNET UNIVERSITY

2000


Question & Answer

Debugging

Documents

opnet technologies

copyright copyright

opnet modeler model

use of opnet debugger

scenarios simulation

process models

challenge debugging

debugging process step