NETWORK SIMULATOR

1
NETWORK SIMULATOR

• Duke Lee, Mustafa Ergen, Jeff Ko
• WOW
• UC Berkeley

2
Simulator

• Animator input
• 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)

3
Simulator

• Finite State Machine
• Event Driven Simulation
• Seed
• State List
• Simulation Functions
• Handler Functions

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
5
Scheduler Algorithm

• struct event
• struct event next
• struct event prev
• unsigned long expiration
• unsigned long data
• void (handler)(unsigned long)

6
Event Scheduler

• add_timer( event ev)
• delete_timer(event ev)
• mod_timer(event ev)
• while(1)
• tmptake_event()
• update_clock
• update_position
• tmp.handler()

SIMULATOR
Event Queue
add_event
take_event
7
Event Queue
Event Queue
CHANNEL
Packet transmission
tx_1
timer_7
tm_7
rx_5
rx_2
rx_1

• Packet Transmission
• Timer initialization

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
9
Architecture

• Overall Design

SIMULATOR MODULE
LINUX MODULES
CHANNEL MODULE
VISUAL TRACER GUI
DEV1
DEV2

DEV3
INFO
INFO
INFO
ANIMATOR GUI
State List
State List
State List
ANALYZER GUI
SCHEDULER
10
Interface

• Initialize_simulation
• Initialize_topology
• Initialize_traffic
• Initialize_record_function
• Main Loop

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)

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)

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)

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)

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.

16
5 Inside Functions

• Randomize Functions
• basic random function should be used for
  determinism.
• unsigned long net_random(void)

17
Conclusion

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

18
NAM

• Allows backward and forward run
• Node variables color,shape
• Node marking
• Variable Tracing
• Annotation
• Node Exec Button
• Save frames as a movie

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.
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)