NAME

       owltsim - one-way light time transmission delay simulator

SYNOPSIS

       owltsim config_filename [-v]

DESCRIPTION

       owltsim delays delivery of data between pairs of ION nodes by specified lengths of time,
       simulating the signal propagation delay imposed by distance between the nodes.

       Its operation is configured by delay simulation configuration lines in the file identified
       by config_filename.  A pair of threads is created for each line in the file: one that
       receives UDP datagrams on a specified port and queues them in a linked list, and a second
       that later removes queued datagrams from the linked list and sends them on to a specified
       UDP port on a specified network host.

       Each configuration line must be of the following form:

           to from my_port# dest_host dest_port# owlt modulus

       to identifies the receiving node.
           This parameter is purely informational, intended to make owltsim's printed messages
           more helpful to the user.

       from identifies the sending node.
           A value of '*' may be used to indicate "all nodes".  Again, this parameter is purely
           informational, intended to make owltsim's printed messages more helpful to the user.

       my_port# identifies owltsim's receiving port for this traffic.
       dest_host is a hostname identifying the computer to which owltsim will transmit this
       traffic.
       dest_port# identifies the port to which owltsim will transmit this traffic.
       owlt specifies the number of seconds to wait before forwarding each received datagram.
       modulus controls the artificial random data loss imposed on this traffic by owltsim.
           A value of '0' specifies "no random data loss".  Any other modulus value N causes
           owltsim to randomly drop (i.e., not transmit upon expiration of the delay interval)
           one out of every N packets.

       The optional -v ("verbose") parameter causes owltsim to print a message whenever it
       receives, sends, or drops (due to artificial random data loss) a datagram.

       Note that error conditions may cause one delay simulation (a pair of threads) to terminate
       without terminating any others.

       owltsim is designed to run indefinitely.  To terminate the program, just use control-C to
       kill it.

EXIT STATUS

       "0" Nominal termination.
       "1" Termination due to an error condition, as noted in printed messages.

EXAMPLES

       Here is a sample owltsim configuration file:

       2 7 5502 ptl07.jpl.nasa.gov 5001 75 0
       7 2 5507 ptl02.jpl.nasa.gov 5001 75 16

       This file indicates that owltsim will receive on port 5502 the ION traffic from node 2
       that is destined for node 7, which will receive it at port 5001 on the computer named
       ptl07.jpl.nasa.gov; 75 seconds of delay (simulating a distance of 75 light seconds) will
       be imposed on this transmission activity, and owltsim will not simulate any random data
       loss.

       In the reverse direction, owltsim will receive on port 5507 the ION traffic from node 7
       that is destined for node 2, which will receive it at port 5001 on the computer named
       ptl02.jpl.nasa.gov; 75 seconds of delay will again be imposed on this transmission
       activity, and owltsim will randomly discard (i.e., not transmit upon expiration of the
       transmission delay interval) one datagram out of every 16 received at this port.

FILES

       Not applicable.

ENVIRONMENT

       No environment variables apply.

DIAGNOSTICS

       The following diagnostics may be printed to stdout:

       owltsim can't open configuration file
           The program terminates.

       owltsim failed on fscanf
           Failure on reading the configuration file.  The program terminates.

       owltsim stopped malformed config file line line_number.
           Failure on parsing the configuration file.  The program terminates.

       owltsim can't spawn receiver thread
           The program terminates.

       owltsim out of memory.
           The program terminates.

       owltsim can't open reception socket
           The program terminates.

       owltsim can't initialize reception socket
           The program terminates.

       owltsim can't open transmission socket
           The program terminates.

       owltsim can't initialize transmission socket
           The program terminates.

       owltsim can't spawn timer thread
           The program terminates.

       owltsim can't acquire datagram
           Datagram transmission failed.  This causes the threads for the affected delay
           simulation to terminate, without terminating any other threads.

       owltsim failed on send
           Datagram transmission failed.  This causes the threads for the affected delay
           simulation to terminate, without terminating any other threads.

       at time owltsim LOST a dg of length length from sending node destined for receiving node
       due to ECONNREFUSED.
           This is an informational message.  Due to an apparent bug in Internet protocol
           implementation, transmission of a datagram on a connected UDP socket occasionally
           fails.  owltsim does not attempt to retransmit the affected datagram.

BUGS

       Report bugs to <ion-bugs@korgano.eecs.ohiou.edu>

SEE ALSO

       udplsi(1), udplso(1)