Hi,

Thanks for your response, answers below.

----- Mail original -----
> 
> From what I know and have read on the Internet, this usually
> happens when your Linux NAT box hits the IPtables connection
> tracking limit. This limit is set via /proc.
> 
> A quick search on the web reveals many sites that tell
> you how to increase the conntrack limits.

Yes, but every tunning I'll do will be lost when VirtualRouter VM
will be re-instanciated.

As all monitoring we could manually had on this VM. 
I've heard there's are request for enhancement concerning VirtualRouter VM
real-life monitoring (and not juste, it's ok, I'm running :)). 
I will try to +1 them.

> 
> However, what would be interesting to know why you hit the limit
> in the first place. Any signs of network abuse? Lots of connections
> in TIME_WAIT state?

Yes, and the only way to find it was to tcpdump on VirtualRouter VM.
2 hosts were making accidentaly to much DNS requests (hundred by seconds).

As soon as the "DoS" on the VirtualRouter VM was stopped, we could again 
create/start virtual machines on cloudstack.

Regards,

-- 
Laurent Steff

DSI/SESI
INRIA
Tél.  : +33 1 39 63 50 81
Port. : +33 6 87 66 77 85
http://www.inria.fr/

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