rtiddsping discovery w/o data

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rtiddsping discovery w/o data

Hello--

I'm trying to establish DDS connectvity between two hosts, which are now directly connected with 10GB fiber to hopefully simplify the testing as previously there was a 10GB switch involved.

After following advice across several posts on this forum, I've brought the experiment all the way down to these two directly connected hosts and am using only the rtiddsping application with no special arguments or QoS settings, including verifying that the environment is clean and the process is not reading any QoS files.

The two machines are a SuSE SLES11.3 host (sdac [x.87.81.174]) and a SuSE SLES12.2 host (stratus-storage-node-1 [x.87.81.175).   RTI Connext is version 5.2.3.

First the problem statement with picture:rtiddsping discovers but sends no data

Also shown is rtiddsspy output on each machine (the left-right windows align with the same hosts above).  I can see that discovery happens: The "R +N" and "W +N" lines appear followed by both sides seeing the data packets starting with "d +N" and followed by "d +M" entries.

I know multicast is not blocked and the hosts have joined the default 239.255.0.1 group when the apps are running:

Multicast Group Output

I've also confirmed that UDP works in the port range DDS will use (shown here in the same publisher [sdac] ==> subscriber [stratus-storage-node-1]) direction as the preceeding output captures.

UDP Works

The interfaces support multicast and there are no errors; the displayed dropped count on the recevier didn't increase throughout the duration of the testing shown in these captures.  They also have matching MTU sizes (which I read about being an issue in a forum post here).

Interface Details

And the routing configuration should be delivering all packets to the right places, especially given the successful individual multicast and UDP tests above.  Both hosts are on the same subnet.

Routing details

I've also dug in with wireshark and observed confirmation of the above in the form of IGMP join / leave packets and the data flowing across the link.

The question is, why doesn't the subscriber indicate that it actually received the data?

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sara's picture
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Hi Rich,

Have you tried our Wireshark integration to see the RTPS packets? Are you seeing the discovery information in both sides?

Thanks,
Sara

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I didn't specifically use the RTI integration with Wireshrk, but I did use wireshark and I did confirm that discovery traffic happens from both sides.   The ping servers and client also both indicate as much in their output that they know the other side is there but the data packets did not flow.

sara's picture
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Last seen: 1 week 2 days ago
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hi Rich,

The RTI integration with Wireshark will help you to undrestand if both phases of discovery (participant and endpoint) is happening.

Anyway, it would be great to see what is actually sent in both sides of your communication. And why the data is not sent. If you have an active support account, it would be great if you could open a case and share those. I know a public forum is probably not the best place to share wireshark traces :)

All the best,
Sara