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adabrowski

Optimal QoS settings for high packet loss network

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Hi,

 

What are the recommended QoS settings for high packet loss networks?

 

I am simulating packet loss with netem tool and it seems that more packets are lost then expected. I would like to receive all packets between two nodes, having all the time that is needed after last packet was published. The context of these tests is comparing OpenSplice to eProsima FastRTPS (and possilby other DDS/RTPS solutions) and evaluating them.

 

Unfortunately, for OpenSplice, setting history to KEEP_ALL, durability to TRANSIENT and reliability to RELIABLE doesn't provide this behavior (setting is on both ends and on the topic). All other QoS settings are default.

 

Problems starts usually above 30% loss, more often near 40%. I am assuming that with indefinite time all packets should be properly delivered even with 90% packet loss.

 

Packets are sent every 300 ms and are small (16 bytes), for a duration of 3 minutes. It is the first packets that are never received (i.e. all until the number 50). Before sending starts, there are 5 seconds to connect. Time to receive first packet varies as expected, but what is unexpected is that it influences total loss rate.

 

I can of course provide code (it's a github public project), but I am hoping for a theoretical answer first.

 

Thank you!

Adam

 

P.S. For best effort settings with no history packet loss is also higher than expected (also a bunch of first packets are lost).

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Hi 

 

For your system , you can run examples throughput and ping pong to know if your network environment and computer is fine .

 

For your program , you can use ospl tuner check topic QoS  or restart ospl , the tuner can be a reader and writer to test .

 

And if is the 5 seconds to connect  enough ? I don'k now , maybe check DDS_PUBLICATION_MATCHED_STATUS before sending .

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