[zeromq-dev] Seldom publisher is not listened to for long ?

[Michael Holm]

2011/5/16 Martin Raspaud <martin.raspaud at smhi.se>:

> I have a very simple pub/sub scheme (1 pub, 1 sub) talking over an IPSec
> tunnel.
>
> This seems to work great when publishing messages regularly. However, a
> typical use case for us would be to publish one message every two or
> three hours. In those cases we have noticed that the subscriber after a
> while is just not receiving any messages anymore (no obvious error
> message or so).
>
> We fixed the problem by implementing a heartbeat, but I'm a bit
> sceptical. ZeroMQ should know better, right ? Or maybe is this not a zmq
> problem, maybe it's related to an underlying network layer ? Does anyone
> have an idea on this ?

It's possible the tunnel itself has a timeout for inactivity, and you
can presumably raise this. Sending a keep-alive heartbeat is an OK
workaround but obviously not as good as understanding what's actually
going on.

-Pieter

IPSec tunnels typically disconnect after a time period and then will automatically reconnect as soon as someone tries to access a vlan routed over that connection. What is weird is that if you have an established socket connection I would think that is enough to keep the tunnel alive. There might be an option set on the tunnel that disconnects after n minutes if no traffic has been sent even if there is an existing connection. You need to chat with the team responsible for setting up the tunnel.

Michael

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