I am doing simulation on datacenter network. I use inet TCPBasicClientApp module for TCP traffic. In my simulation, I feed a set of TCP flows from a file. It works for most of the tests, but in some tests I got the error:
Module Error: Ephemeral port range 1024..5000 exhausted
I tried to figure out, but it seems out of my control, because this error comes from Inet TCP module.
After digging up Google, I got an idea that the error is related to 2 parameters:
thinkTime
idleInterval
They said as soon as they increased them, the problem is solved.
I was setting both at 1s; then tried to increase it to 2s, and 5s for both parameters, but the error still remains.
So is there anyone has faced this error and got rid of it, or has any idea to fix this error just share me please? I very much appreciate any help.
Best,
Danh
Hi all, let me update my solution for this problem, in case someone need to refer. So instead of using ephemeral local port which is limited in a range (1024--5000), I use normal port number by setting the parameter localPort, with initial value of 2000 then increases by 1 for every new socket. By setting that I don't see the error anymore, so I guess my simulation now can serve as much as the maximum port number supported in Omnet, e.g, 65535 ports. Thanks.
Best,
Danh
Related
I am still leaning python and Nornir for network automation as a network engineer.
I am scripting to find any BGP issue from multiple devices with Nornir using "TextFSM".
The python with nornir works correctly without "TextFSM.
I get an error message when TextFSM is used for parsing.
I searched and spent time a lot to find the reason of this issue.
Half of the network devices I am managing has the issue with "TextFSM" at present.
Could you please advise me where I can start to fix this issue?
Thank you.
I get the output with netmiko like below
output = net_connect.send_command('show ip bgp summary')
Here is the output of "print(repr(output))
I have a shiny app deployed on a virtual machine with the free version of shiny server. It works without any issues locally, and when accessed through the localhost (same intranet).
However, after adding Apache and an SSL certificate to be able to access to the app from anywhere is when some issues with disconnecting have appeared.
The app disconnects when it needs to do longer calculation (~ 1 minute long). However, before disconnecting it shows the result of that calculation, (in this case a plot with plotly).
I get these errors:
Firefox can’t establish a connection to the server at https://*****/websocket
Connection closed. Info: {"type":"close","code":4704,
"reason":"Protocol error handling message: Error: Discard position id too big","wasClean":true}
The log file on /var/log/shiny-service/.log does not show any errors:
This is the last line: Please specify in ggplotly() or plot_ly(). A message that doesn't cause any error.
I have already tried everything I could find like:
Apache Configuration:
keepAlive On
MaxKeepAliveRequests 0
Shiny Server Configuration:
app_init_timeout 300;
app_idle_timeout 300;
I have no idea what else to try to solve this, and any help would be highly appreciated.
Edit
This is how the app looks after it disconnects, the plot has been generated, after a minute, however it still disconnects automatically.
I believe you can remediate the problem by increasing the values of app_init_timeout and app_idle_timeout. Please see this SO thread and these related docs. Also see this (regarding the Apache MaxKeepAliveRequests option).
I would find the best values by trial and error, but based on other users comments it may need to be as high as 1800. I imagine the reason it works on your LAN is that the latency that way would be much lower.
Having said all that, if the time taken is so high then there's probably something in the app that needs to be recoded in some way or which relies on some data set that is too large. You can probably test this by reducing the size of the data sent to plot.ly or the scope of the calculations being computed then see if the problem goes away.
At the moment I have a problem I cannot pin down. Seemingly at random my communication with my RS232 Alicat Device will get held up. It will get held up somewhere in the read or write process and be unable to complete it. Upon closing the VI I will get a "Resetting VI" error in Labview 2020. I am using 7 of the 9 RS232 ports. My question is:
How do I fix this problem so that I do not get a communication drop OR (more likely)
How do I code the system such that I can catch and move through this problem or reset the connection. Something of a VISA read/write timeout? Open to ideas on how to move past the block
Here is what I have gathered about the problem:
Windows 10, I’ve tested everything on multiple computers. It happens no matter what.
It happens at random. It might happen twice within 20 minutes or not for a couple of hours.
I have never experienced the error when probing the line. I don’t know if that is a clue, or if that speaks to the randomness of the problem
Baud Rate = 9600, Prior to this I was running at 19,200 and experienced equivalent issues. The manufacturer recommended lowering the baud rate to reduce noise. I have also isolated the cable from other parts of the hardware. At this point noise on the connection is not an issue, but I am still experiencing the error.
My buffer size is 1000 bytes.
By termination character is \r. I cannot imagine a scenario where it fails to read a termination character due to the size of my buffer
I'm querying it every 50ms. Far below the threshold of a standard timeout. Too much?
What I am currently testing.
Due to how my code block is setup I cannot yet confirm if it is getting locked up on the read or write block or both. I'm attempting to isolate the problem with only minor modifications to see if I can isolate it.
Attached is slimmed down version of my code that I isolated the error to.
I have experienced similar problems with some RS232 devices from different suppliers. The (quite bad) solution was to connect and disconnect for each communication command. The question would be what sample rate you need.
Another idea is to replace that device with an ethernet device. If I am not mistaken Alicat supplies those with Modbus (TCP).
The issue turned out to be specific to windows/my laptop. There is a USB setting that disables inactive USB's after a certain amount of time. The setting to disable the timeout was unavailable through the control panel on my laptop, though it was available on my coworkers. I had to use powershell commands to change the setting
i am doing some simulations of DDOS SYN FLOOD attack on a real network using virtual machines and i want to modify the current behavior of TCP three-way-handshake on Linux Mint, can anyone give me a guide or the steps to do ?
If you want to change the kernel code, then you need to know where they are, and then edit the code, compile them and run. Here is a network can help you know how to do these things, but the knowledge of Linux network stack is not include.
I am executing my MapReduce program on a Multinode cluster with 3 nodes. While executing I am getting the error "Status:failed Too many fetch failures" after MAP 100% was reduced to 16%, so why am I getting this error?
How can I solve this?
The reasons for the error could be DNS issues, http threads on the mapper side or JVM bug that cause connections to get map outputs fail. Please look at this http://archive.apachecon.com/na2013/presentations/27-Wednesday/Big_Data/14:45-7_Deadly_Hadoop_Misconfigurations-Kathleen_Ting/HadoopTroubleshootingApacheCon.pdf. You can find solution on slide number 24.
Hope this helps