Ping issues since Ubuntu 12.04.2 Zabbix proxy

[joergi]

Hello together,

we are using a distributed monitoring and in the past we have used a OpenSuSE 11.4 with Zabbix 2.0.1 (old Proxy) on the proxies. The central Zabbix server is running with Zabbix 2.0.3.
Now I have build a new Zabbix proxy 2.0.6 on Ubuntu 12.04.2 LTS and I get ICMP ping issues. The firewall is disabled on the Ubuntu and in the example screenshots, the monitored server is in the same network within the proxy.
If I connect the old proxy, it is working - no ping loss / ping is up. With the new one, I am getting the "sawtooth" in the graphs.
I don't know what is wrong on the Ubuntu proxy.
Do you have a idea, what could be wrong on the Ubuntu / Proxy configuration? At the moment I am totally clueless .

Thanks in advance,
Jörg

[joergi]

I did a double check for the ufw of Ubuntu and it is inactive.

Regards,
Jörg

[joergi]

I did a downgrade to Ubuntu 10.04 and now it is working fine. No issues.
What is going wrong with Ubuntu 12.04 (Kernel? I don't know)?

Regards,
Jörg