On 06/05/2014 12:37 PM, thus George Dunlap spake: > On Wed, Jun 4, 2014 at 7:40 PM, Timo Schöler <timo at riscworks.net> > wrote: >> -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 >> >> Hi list, >> >> I searched the web for bug reports regarding this phenomenon I >> see on *multiple* machines of a customer, however, I didn't find >> an exact fit. So, I'd like to ask here whether anyone else has >> run into this. >> >> I have multiple CentOS 6 machines running using KVM to virtualize >> a bunch of machines on them (LVM-based). >> >> Software releases as following: >> >> [root at fe00 ~]# rpm -qa|egrep '(virt|kvm)' >> virt-viewer-0.5.6-8.el6_5.3.x86_64 >> libvirt-python-0.10.2-29.el6_5.7.x86_64 >> libvirt-client-0.10.2-29.el6_5.7.x86_64 >> qemu-kvm-0.12.1.2-2.415.el6_5.8.x86_64 >> libvirt-0.10.2-29.el6_5.7.x86_64 >> python-virtinst-0.600.0-18.el6.noarch >> >> [root at fe00 ~]# uname -r 2.6.32-431.17.1.el6.x86_64 >> >> The VMs (here: two) have the "default" connection provided by >> KVM (heading to the internet) as well as a bridged interface to >> connect to a high performance backbone, where sensitive data is >> kept and bandwidth is an issue (or better, not :), on a second >> interface within the VMs: >> >> [root at fe00 ~]# brctl show bridge name bridge id STP enabled >> interfaces br1 8000.001b21xxxxxx yes >> eth1 vnet1 vnet3 virbr0 8000.525400xxxxxx yes virbr0-nic >> vnet0 vnet2 >> >> br1 is the interface connected to the backbone, virbr0 KVM's user >> mode network. >> >> After some time of inactivity on the virbr0 interface, from >> *within* the VMs connection is *lost*. The interface(s) lose >> their IP; running dhclient(8) is not of any use. >> >> To get the machine back onto track, ``service libvirtd restart'' >> has to be issued: Vanished iptables rules show up again. (This, >> in contrast to an Ubuntu document [0], fixes it without shutting >> the VM(s) down.) Starting dhclient(8) within the VMs gets >> connectivity back. > > Have you verified that the iptables rules disappear? That is: * > Initially, the NAT rule is present * After inactivity, the NAT rule > disappears * After restarting libvirtd, the NAT rule re-appears? > > -George Hi, yes, it's exactly that way it happens. Timo