I'm having a problem with a Debian 6 server where it looses network connectivity and doesn't come back (server does not respond to pings, and can't connect to any services). The problem happens sporadically. Some times it will go a month without the problem occurring, while other times it will happen within a few days of being rebooted.
When logged into the console, I confirm that the server doesn't seem to have network conectivity (can't ping 18.104.22.168 for example). All services are running though (mysql, Apache, SSH, etc).
When the problem happens, the network interfaces are up (I checked ifconfig, all interfaces looked normal). I also check iptables, and verify there were no rules that would block anything. I also try running /etc/init.d/networking/restart, but that does not fix the problem. The only thing I've found that fixes the problem is rebooting.
The server is a virtual machine with a wired connection in a data centre. The company I rent the server from thinks the problem is due to high RAM usage. They said that the server was frozen due to resource exhaustion and the server stopped responding to ICMP requests, referencing this:
root@vm2:~# free -m total used free shared buffers cached Mem: 8181 7816 365 0 364 6201 -/+ buffers/cache: 1250 6931 Swap: 8191 0 8191
Do you think that high RAM usage could have anything to do with this problem? I think it is something else, but I don't know what else to check.