TCP app working strangely if the number of connection is above 30 connections

[gooner87]

Overview: The TCP app in INET 4 (TcpSinkApp and TcpSessionApp combination) is working in a unstable fashion if the number of TCP connections exceed 30. The simulation is working as expected until the number of TCP connection are 30. If the number of connection is increased gradually one by one above 30, working TCP connections are mostly 30. For some random values above 30, only 2 connections were intact. For Eg, a scenario with 34 TCP connections were setup and ran. only 30 connections were able to receive data. To check for any issue in those remaining 4 connections, in another scenario, those 4 TCP connections which were not working in above case were simulated, but it was working as expected.

The individual connections were running with very low data rate transmission and I dont see any BandWidth issue here.

Note1: It has to be noted that the same connection was working properly in INET 3 Note2: The same scenario is working fine with UDP app in both INET3 and INET4

The ini and ned files where I found the issues are attached along. Below steps will provide the requirement information to recreate the issue. Steps to recreate the issue:

1. Rename 34 TCP.txt to 34 TCP.ini and NED.txt to NED.ned
2. Change "network- " part depending on the location you placing these files.
3. Files mentioned in step1 has 34 TCP connection for a simple topology. SImulate it now.
4. Check the vector files and see which all connections were working
5. The vector file will show that 4 connections are not working.
6. Now rename the file "4 working.txt" to "4 working.ini" and run after making proper change. It will show that the connections where were not working in step 4 is working fine

4 working.txt 34 TCP.txt NED.txt