[zeromq-dev] ZeroMQ behavior in satellite networks (high variable latency)

[Sylvain Fabre - INPIXAL]

Hi, 

I am using ZeroMQ since more than 6 years now, and the library has proven its high efficiency and its stability.

But since a few days, i am facing an issue. Here are the facts : 

  - I push video packets on a satellite network, thru a PUSH-PULL pattern, associated with a ROUTER-DEALER pattern for the control/command.
  - The PUSH-PULL pattern is working perfectly well on local LAN, pushing 10 streams at 2.0 Mb/sec each without any issue
  - The satellite network offers "high" bandwidth (approx 30 Mbs), and variable latency (let's say between 300 and 900ms)
  - On the satellite network, it becomes unusable : even 1 single PUSH-PULL link is not able to push 2.0 Mb/sec

In order to understand the issue, i simulated the satellite network with "netem", on my local LAN : 

  - When using a constant latency (ie 700 ms for example), everything is working fine (command : tc qdisc add dev eth1 root netem delay 700ms)
  - But as soon as i use a variable latency, i reproduce the behavior of the satellite network (command : tc qdisc add dev eth1 root netem delay 900ms 200ms 25% )

Do you know why ZMQ behaves like this ? I guess this is linked to the bandwith management, so is there any way to deal with this variable-high-latency thing ?

Thanks !

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