Changing bandwidths of each ISL

[jttan3]

I was wondering if I can change the bandwidth of each ISL during the simulation, is there a function built in that could do that already? If not, is it possible to extend the code to allow for that? I am looking to change the bandwidth depending on the location of the satellite.
Thanks

[xiex386]

There is no such function at the moment.
A simple way to do this is to add an API in orchestrater which can be called by StarryNet controller remotely. Do you need to configure all ISLs during emulation one by one? If so, the emulation efficiency may be a problem.

[jttan3]

Thanks for the reply, I tried to follow the sn_delay_change function to change the bandwidth. It seems to work for a simple example. Would this be a valid way to change the bandwidth during the emulation?
I can see how the efficiency will be a problem, we are planning to make bandwidth changes for ISLs one by one at every certain emulation time step based on traffic of the link. Will this bandwidth change cause problems for other parts of the emulation, or will it just take alot of time?

[xiex386]

This time cost does matter. It will delay the emulation event loop and cause distortion.

[jtandiarytan]

Could you explain more about what you mean by distortion?
Also, I am trying to simulate traffic through the network. I am worried I might have misunderstood how to use the simulator. My approach is to generate a traffic matrix that represents an adjacency list between ground stations. The entry i, j represents how many times I call perf between the two ground stations (this is just a test of whether I can increase the number of perfs).
While the perf tests in example.py worked before, paramiko is giving an ssh error when trying to perf many times with the traffic matrix. This led me to think that this is not the correct usage of the simulator. Is this not the way to simulate traffic, or is this the machine not being powerful enough to support many perfs?
Thank you, I really appreciate your help and responses.
tldr: what is distortion, and how can I simulate traffic in starrynet?

[xiex386]

The distortion means the inconsistencies in system because the execution of a large number of events in a short period of time may overwhelm the system and slow down the regular operation events including link creation and update.
As for the traffic simulation, I'm not sure about your ssh error. Could you please detail the error output?

[jtandiarytan]

Exception in thread Thread-179:
Traceback (most recent call last):
  File "/usr/lib64/python3.9/threading.py", line 980, in _bootstrap_inner
    self.run()
  File "/usr/lib64/python3.9/threading.py", line 917, in run
    self._target(*self._args, **self._kwargs)
  File "/home/cs525/StarryNet/starrynet/sn_utils.py", line 1104, in sn_perf
    perf_result = sn_remote_cmd(
  File "/home/cs525/StarryNet/starrynet/sn_utils.py", line 165, in sn_remote_cmd
    stdin, stdout, stderr = remote_ssh.exec_command(cmd, get_pty=True)
  File "/usr/local/lib/python3.9/site-packages/paramiko/client.py", line 560, in exec_command
    chan = self._transport.open_session(timeout=timeout)
  File "/usr/local/lib/python3.9/site-packages/paramiko/transport.py", line 994, in open_session
    return self.open_channel(
  File "/usr/local/lib/python3.9/site-packages/paramiko/transport.py", line 1136, in open_channel
    raise e
paramiko.ssh_exception.ChannelException: ChannelException(2, 'Connect failed')

This is the error I get when trying to run a large number of perfs. I can see some perfs are successful even when this error shows up. I am currently running 10 x 10 satellites with 10 GS, running 5 - 10 perfs between each ground station from 5 s to 100 s. I also set that each second can only have a max of 10 perfs. The amount of times the error shows up varies, sometimes only a little, but sometimes more often. Even without the bandwidth adjusting logic this error occurs when setting a large number of perfs.

Emulation in No.42 second.
A change in time 42:
add link 49 108
[Create GSL:]docker network create GSL_49-108 --subnet 9.8.49.0/24
[Add current node:]docker network connect GSL_49-108 2e2d1fb2fbd1 --ip 10.8.49.50
Exception in thread Thread-9:
Traceback (most recent call last):
  File "/usr/lib64/python3.9/threading.py", line 980, in _bootstrap_inner
    self.run()
  File "/home/cs525/StarryNet/starrynet/sn_utils.py", line 711, in run
    sn_establish_new_GSL(
  File "/home/cs525/StarryNet/starrynet/sn_utils.py", line 1313, in sn_establish_new_GSL
    target_interface = str(ifconfig_output[0]).split("@")[0]
IndexError: list index out of range

I am also getting this error during the link update. Removing the bandwidth update code still gives the error. I saw #24 also mentioned a list index error but its not quite the same.