scenario_description

opnet环境中实现aodv路由协议建模

    This AODV sample scenario has 18 wireless  lan based stations in the
ad hoc network configuration.   Nodes move around in a rectangular area 
whose boundaries ([grid_XMIN - grid_XMAX] x [grid_YMIN - grid_YMAX]) are 
defined by the user at the node level. 

    The mobility scheme is very  limited and is activated by setting the
MOBILITY attribute (node level) to "Enabled".  The movement is a
sequence of discretized events and no acceleration is possible. At each 
interval I,  a node chooses a direction based  on a  given  distribution 
and  move along a distance D.  The values of I (mobil_POS_TIMER)  and  D
(mobil_STEP_DIST) are defined by the user at the node level.  Each time
a node encounters a boundary, it reflects on it (billiard scheme).

    As far  as packet  generation is  concerned, a node's source traffic
activity  is  determined by the INTERLOCUTOR attribute.  If it is set to
"None", the  node  remains silent (but still  performs its  routing func-
tion)  during  the  simulation  time.  If  INTERLOCUTOR  is  set  to 
"Multiple",  node  may  sequentially  `converse`  with  multiple  nodes 
(each  time a packet is  received at the app_manager from the source,  a
destination is randomly computed and attributed to it  before it is sent
to  the  routing  layer).  Finally,  it  is  possible  to define a mono-
interlocutor by  indicating its address in the sub-network.  All packets 
generated at the source are then destined for the specified node.

    To enable the Hello Mode,  the user  needs  to  set  the  HELLO_MODE 
attribute  (node level)  to the "Enabled" value. The use of 
hello  message exchange  to maintain local connectivity  leads to longer
time of execution.

    The GRAT_RATIO attribute (node level) indicates the ratio of gratui-
tous  requests  for  each  node.  If  set  to "O", no gratuitous mode is 
requested.

   As far as statistics  are  concerned,  users are invited to implement 
their own. However, some data are written into a log file (output_file)
at the end of each simulation run: intput (nb of pks), output (nb of pks).

   Finally,  it is possible to trace the simulation execution by printing
short messages on the screen.  For each node,  messages can be printed in 
along  the  simulation  time  in  order  to  track  its  evolution within 
the  network.  As a matter of fact,  these  messages  provide information 
about its position, its current state on the process, and its response to
the  current  events.  This  feature is controlled by the DEBUG attribute 
(node level)  whose  value  indicates  the quantity  of information to be 
displayed on the screen (DEBUG = "second_level" is recommended). If DEBUG
is set to "None", no messages will be printed.