Problem with 'resource temporarily unavailable'

[Guus Sliepen]

On Wed, Jan 15, 2003 at 01:10:24PM -0600, Edward King wrote:

> We've got problems running tinc over DSL lines using low cost 
> routers/modems (at leat I think it's a hardware problem.)
> 
> We get error messages such as the following:
> 
> Jan 15 11:36:05 stv100 tinc.stv100[2784]: Sending meta data to vpn 
> (162.37.22.162 port 2007) failed: Resource temporarily unavailable

That usually indicates that no more network buffers are available,
either because the machine is really low on memory or if more data is
being sent out by tinc than the network can handle.

tinc normally shouldn't send very much meta data (only a ping once a
minute and some updates if a connection to another tinc daemon is made
or broken) unless you're using the TCPonly option. Is it really
necessary for you to use it? What kind of traffic are you sending over
the VPN?

> I've added a delay to meta.c so if it errors out, retry in 1 second 
> (using usleep(1000)).  I also made an it log every time it was going to 
> retry and if it fails, log the failure.  the code looks like this:

usleep(1000) sleeps for 1 millisecond.

> we also changed the mtu on both sides to 1000 -- hoping to possibly 
> remove problems there.

That probably doesn't matter much.

> We now get lots of 'will retry in 1000ms' messages, and very few 
> 'failed' messages.  

That's interesting.

> There are more messages on the sending side of 'Metadata socket error 
> for vpn' Connection reset by peer' and the other side showing 'Bogus 
> data received'

You really shouldn't see that unless errors were introduced in the TCP
stream... Do those errors also occur less frequently with the usleep()
than without?

-- 
Met vriendelijke groet / with kind regards,
    Guus Sliepen <guus at sliepen.eu.org>
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