[CentOS-virt] KVM integrated network (user mode) dying after inactivity
timo at riscworks.net
Thu Jun 5 13:10:01 UTC 2014
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>
>> -----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)'
>> [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 , 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?
yes, it's exactly that way it happens.
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