tapbridge-CSMA, NS3-flowmonitor

[Ayman Sabbah]

Hi,

I made some progress in injecting traffic from CORE to pure NS-3 nodes. This was possible by using CSMA netdevices along with tapbridges. The network design is attached.

Consider that the cloud CORE/NS-3 is representing a pure NS-3 node with two CSMA devices and IP addresses: 10.0.8.2 and 10.0.9.2.

The interesting behavior of this network is that I can reach 10.0.8.2 device from 10.0.9.3 node (and even from an outer PC in the 10.0.4.0 subnet).

Also: I can reach 10.0.9.2 device from 10.0.8.3 node (and even from an outer PC in the 10.0.5.0 subnet).

However, if I attempt to ping the 10.0.8.3 from 10.0.9.3 or ping 10.0.9.3 from 10.0.8.3, core gets dumped with: " assert failed cond="m_current >= delta", file = ./ns3/buffer.h, line 859"

I am attaching the pcap file and the asccii files. As it appears in the BB Net1.tr file, the system breaks down at the instance of ns3::EthernetTrailer (...

Can anybody give me an insight to why does this happen? is it because of bug 2078 (https://www.nsnam.org/bugzilla/show_bug.cgi?id=2078)

It will be great if you can provide me with some ideas on how to solve this issue.

Another problem I am facing is using the flowmonitor: even when having a single CORE/NS-3 node and another NS-3 node with a CSMA device, if I install flowmonitor on the ns-3 node, the session will start normally without errors but it will break within 1-2 seconds with a segmentation fault and without giving any reason. Any idea why does this happen?  Is there a way that enables debugging the program while it's running because it seems the problem is due to interacting with the tapbridge which cannot be seen under gdb debugging.

Thanks for your help,

Ayman I. Sabbah, Ph.D.,

Communications Research Centre (CRC) - Innovation, Science, and Economic Development (ISED) Canada,

​ ​

Ottawa, ON, K2H 8S2. 

[Tommaso Pecorella]

Hi,

yes, the problem could be caused by bug 2078. Try to disable metadata: packets won't be printed, but the problem could go away.

About debugging TapBridge... boh ? I'd suggest to add log lines. Those always works.

Cheers,

T.

[Ayman Sabbah]

Thanks Tommaso for your response. I will try your suggestion next week.

You're awesome!

Ayman I. Sabbah, Ph.D.,

Communications Research Centre (CRC) - Innovation, Science, and Economic Development (ISED) Canada,

Ottawa, ON, K2H 8S2. 

Website: https://sites.google.com/site/asabbah84/

LinkedIn: https://ca.linkedin.com/in/asabbah

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