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NETWORK SIMULATOR

Duke Lee, Mustafa Ergen, Jeff Ko

WOWWOW UC BerkeleyUC Berkeley

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Simulator

• Animator inputDefine geographical distributionDefine the functional parameters of the network nodes.Define network layer protocolsDefine traffic characteristics down to each node.

• Simulator coreNetwork ModulesDrive the event.

• Analyzer outputStatistical graphing tool.

• Visual Tracer outputPacket-level visualization tool. (NAM)

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Simulator

• Finite State Machine

• Event Driven Simulation

• Seed

• State List

• Simulation Functions

• Handler Functions

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Event Scheduler

CHANNEL

INFO.

NODE

• Application

• WTP– timers

• IP– DSDV, etc.

• Link Layer– Timers,WTRP

• Channel– Packet

transmission

• Node Info– position

– topology

SC

HE

DU

LE

RPHSICAL LAYER

LINK LAYER

IPTCP UDP

ICMP

QUEUE

Application

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Scheduler Algorithm

• struct event {struct event *next;

struct event *prev;

unsigned long expiration;

unsigned long data;

void (*handler)(unsigned long);

• }

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Event Scheduler

• add_timer( event *ev);

• delete_timer(event *ev);

• mod_timer(event *ev);

• while(1) {tmp=take_event();

update_clock ;

update_position;

tmp.handler();

• }

SIM

UL

AT

OR

Event Q

ueue

add_event

take_event

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Event Queue

• Packet Transmission

• Timer initialization

tx_1E

vent Queue

rx_5rx_2

rx_1

CH

AN

NE

L

Packet transmission

timer_7tm_7

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Simulator Functions

• update_topology();• record_topology();• record_transmission();• record_reception();

• Record Function is a periodic event which periodically starts monitoring

SIM

UL

AT

OR

Event Q

ueue

record_function

record_topology

Output F

ilesrecord_transmission

record_reception

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Architecture

• Overall Design

DEV1ANIMATORGUI

DEV2

SCHEDULER

…DEV3

ANALYZERGUI

VISUALTRACER

GUI

SIMULATORMODULE

LINUX MODULES

CHANNELMODULE

StateList

StateList

StateList

INFO INFO INFO

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Interface

• Initialize_simulation;

• Initialize_topology;

• Initialize_traffic;

• Initialize_record_function;

• Main Loop

NetworkModule

MO

NIT

OR

ING

CBR

CHANNEL

SC

HE

DU

LE

R

[1]

[2]

[3]

[4]

[5]

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[1] CBR-Data Traffic

• used to send periodic packet to the module.

• sits in the Logical Link Control above the network module.

• transmit (received something from the top layer)

– int tx_handler (struct device *dev, struct sk_buff * skb)

• receive

– int app_rx (struct device * dev, struct sk_buff * inskb, unsigned short network_proto)

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[2] Scheduler

• used to send data to channel module

• transmit first schedule a event and wait about a transmission time.– int transmit (struct device *dev, struct sk_buff skb)

• called when the module get the event from the scheduler.– received something from the bottom layer.– void rx_handler(struct device *dev , struct sk_buff *skb)

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[3] Channel

• scheduler to channel

– void _transmit (struct device * dev)

• channel go through for each node and assign packet reception for those who can get the packet.

• channel to scheduler

– void add_timer (struct timer_list * timer)

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[4] Monitoring Functions I• void record_topology (struct simulation_struct * siminfo,

struct device *device_list, struct device * dev, float time, float difftime);

• void start_transmission (struct simulation_struct * siminfo,

struct device * sender, float time);

• void end_transmission (struct simulation_struct * siminfo,

struct device * sender, float time);

• void start_reception (struct simulation_struct * siminfo, struct device * sender, float time);

• void end_reception (struct simulation_struct * siminfo,

struct device * sender, float time);

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[4] Monitoring Functions II

• void record_transmission (struct simulation_struct * siminfo,

struct device * device_list, struct device * sender,

unsigned char * packet, float time);

• void record_reception (struct simulation_struct * siminfo,

struct device * device_list,

struct device * sender, unsigned char * packet,

float time);

• printpacketinfo (* packet); needed for different packet types.

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[5] Inside Functions

• Randomize Functions

• basic random function should be used for determinism.

– unsigned long net_random(void);

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Conclusion

• Unique Simulator Functions• Specific Handler Functions• Linux Scheduler Functions• General Event Type• NAM

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NAM

• Allows backward and forward run

• Node variables: color,shape …

• Node marking

• Variable Tracing

• Annotation

• Node Exec Button

• Save frames as a movie

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Appendix I

• Transport protocol create sk_buff from output buffers

• While device drivers create them for incoming data.

TCP

IP

MAC

Dev.

sk_buff

sk_buff

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Appendix II

• struct cbr_struct {

• struct cbr_struct * next;

• unsigned long start_time;

• struct device * source;

• struct device * dest;

• struct timer_list cbr_timer;

• int packetsize;

• int numpackets;

• int bandwidth;

• void * handler;

• };

• struct timer_list {

• struct timer_list *next;

• struct timer_list *prev;

• unsigned long expires;

• unsigned long data;

• void(*function)(unsigned long);

• };

• sk_buff• sk – pointer to owning socket• stamp – arrival time• dev - pointer to receiving/transmiting device• h- pointer to transport layer header• nh- pointer to network layer header• mac- pointer to link layer header• dst – pointer to dst_entry• cb –TCP per –packet control information• len – actual data length• csum- checksum• protocol- packet network protocol• truesize- buffer size• head- pointer to head of buffer• data- pointer to data head• Tail- pointer to tail• End- pointer to end• Destructor-pointer to destruct function