NETWORK SIMULATOR

1. NETWORK SIMULATOR Duke Lee, Mustafa Ergen, Jeff Ko WOW UC Berkeley WOW

2. Simulator • Animatorinput Define geographical distribution Define the functional parameters of the network nodes. Define network layer protocols Define traffic characteristics down to each node. • Simulator core Network Modules Drive the event. • Analyzer output Statistical graphing tool. • Visual Tracer output Packet-level visualization tool. (NAM) WOW

3. Simulator Finite State Machine Event Driven Simulation Seed State List Simulation Functions Handler Functions WOW

4. Event Scheduler • Application • WTP • timers • IP • DSDV, etc. • Link Layer • Timers,WTRP • Channel • Packet transmission • Node Info • position • topology SCHEDULER Application INFO. QUEUE TCP UDP ICMP IP LINK LAYER PHSICAL LAYER NODE CHANNEL WOW

5. Scheduler Algorithm • struct event { struct event *next; struct event *prev; unsigned long expiration; unsigned long data; void (*handler)(unsigned long); • } WOW

6. 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(); • } SIMULATOR Event Queue add_event take_event WOW

7. Event Queue CHANNEL Event Queue • Packet Transmission • Timer initialization Packet transmission tx_1 tm_7 timer_7 rx_5 rx_2 rx_1 WOW

8. Simulator Functions • update_topology(); • record_topology(); • record_transmission(); • record_reception(); • Record Function is a periodic event which periodically starts monitoring SIMULATOR Event Queue record_function record_topology Output Files record_transmission record_reception WOW

9. Architecture • Overall Design SIMULATOR MODULE CHANNEL MODULE LINUX MODULES VISUAL TRACER GUI DEV1 DEV2 DEV3 … INFO INFO INFO ANIMATOR GUI State List State List State List ANALYZER GUI SCHEDULER WOW

10. Interface CBR SCHEDULER MONITORING [1] [4] Network Module [5] [2] CHANNEL [3] • Initialize_simulation; • Initialize_topology; • Initialize_traffic; • Initialize_record_function; • Main Loop WOW

11. [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) WOW

12. [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) WOW

13. [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) WOW

14. [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); WOW

15. [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. WOW

16. [5] Inside Functions • Randomize Functions • basic random function should be used for determinism. • unsigned long net_random(void); WOW

17. Conclusion • Unique Simulator Functions • Specific Handler Functions • Linux Scheduler Functions • General Event Type • NAM WOW

18. NAM • Allows backward and forward run • Node variables: color,shape … • Node marking • Variable Tracing • Annotation • Node Exec Button • Save frames as a movie WOW

19. Appendix I • Transport protocol create sk_buff from output buffers • While device drivers create them for incoming data. TCP sk_buff IP MAC sk_buff Dev. WOW

20. 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; • }; • 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 • struct timer_list { • struct timer_list *next; • struct timer_list *prev; • unsigned long expires; • unsigned long data; • void(*function)(unsigned long); • }; WOW