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)