32.5 Commands at a glance
Following is a list of commands used to simulate dynamic scenarios in ns:
$ns_ rtmodel model model-params args
This command defines the dynamic model (currently implemented models are:
Deterministic, Exponential, Manual or Trace) to be applied to nodes and
links in the topology. The first two arguments consists of the rtmodel and
the parameter to configure the model. <args> stands for different type of
arguments expected with different dynamic model types. This returns a
handle to a model object corresponding to the specified model.
- In the Deterministic model <model-params> is <start-time>,
<up-interval>, <down-interval>, <finish-time>. Starting from start-time
the link is made up for up-interval and down for down-interval till
finish-time is reached. The default values for start-time, up-interval,
downinterval are 0.5s, 2.0s, 1.0s respectively. finishtime defaults to the
end of the simulation. The start-time defaults to 0.5s in order to let the
routing protocol computation quiesce.
- If the Exponential model is used model-params is of the form
<up-interval>, <down-interval> where the link up-time is an exponential
distribution around the mean upinterval and the link down-time is an
exponential distribution around the mean down-interval. Default values for
up-interval and down-interval are 10s and 1s respectively.
- If the Manual distribution is used model-params is <at> <op> where
specifies the time at which the operation op should occur. op is one of
up, down. The Manual distribution could be specified alternately using the
rtmodel-at method described later in the section.
- If Trace is specified as the model the link/node dynamics is read
Tracefile. The model-params argument would in this case be the file-handle
of the Tracefile that has the dynamics information. The tracefile format
is identical to the trace output generated by the trace-dynamics link
method (see TRACE AND MONITORING METHODS SECTION).
$ns_ rtmodel-delete model
This command takes the handle of the routemodel <model> as an argument,
removes it from the list of rtmodels maintained by simulator and deletes
$ns_ rtmodel-at at op args
This command is a special interface to the Manual model of network dynamics.
It takes the time <at>, type of operation <op> and node or link on which
to apply the operation <args> as the arguments. At time <at>, the operation <op>
which maybe up or down is applied to a node or link.
$rtmodel trace ns f optional:op
This enables tracing of dynamics effected by this model in the links. <ns>
is an instance of the simulator, <f> the output file to write the traces to
and <op> is an optional argument that may be used to define a type of
operation (like nam). This is a wrapper for the class Link procedure
$link trace-dynamics ns f optional:op
This is a class link instance procedure that is used to setup tracing of
dynamics in that particular link. The arguments are same as that of class
rtModel's procedure trace described above.
This command inserts a DynamicLink object at the head of the queue and signals
to all connectors in the link that the link is now dynamic.
This is an internal procedure that configures all dynamic models that are
present in the list of models maintained by the simulator.