Public bug reported:
I have looked at a lot of other network issues with KVM but the most
close bug report I found mentioned server load as a trigger but for me
the problem is 100% repeatable without server loads going to 100%. Here
is my case:
I have a Dell 2950 server with two virtual machines.
The virtual machines run on a partition instead of a image file.
On the server I made a bridge br0 (like in all wikis)
Both VMs have there own public ip address
Both VMs use virtio as the network interface (see the xml definition below)
Now I start the first VM (VM1)
On a client machine I can connect to the VM1 through ssh and I can start a ping
to VM1
I also start the virt-manager and use the viewer to view the 'machine'. I start
a ping there to www.google.com (so on the VM1 itself)
Now I start the second VM (VM2) and use the viewer on the client to look at the
output.
As soon as the login screen is displayed in the viewer, the ping on the client
to the VM1 stops
The ping on the VM1 viewer to google keeps working! (so there is network on VM1)
A ping on the client to VM2 works
I have started a tcpdump on the server and I can see both pings arrive
on the br0 interface, but only one gives a response!!!
If I stop the VM2 (sudo halt), after the shutdown is complete, the ping
from client1 to VM1 starts working again!
So if I look at the results:
1. When 1 VM is working everything is normal
2. When 2 VMs are running, only one is accessible from the outside, however,
network connectivity from the VM to the outside (through the viewer, ping to
google) is working!
Some other info:
=====
Release is Ubuntu 8.10 on the server and on both VMs, completely updated
kernel: Linux [server] 2.6.27-11-server #1 SMP Wed Jan 28 00:40:58 UTC 2009
x86_64 GNU/Linux
vms: Linux [VM1 and VM2] 2.6.27-11-server #1 SMP Wed Jan 28 00:40:58 UTC 2009
x86_64 GNU/Linux
=====
KVM/virt packages:
ii kvm 1:72+dfsg-1ubuntu6 Full
virtualization on i386 and amd64 hardware
ii libvirt-bin 0.4.4-3ubuntu3.1 the
programs for the libvirt library
ii libvirt0 0.4.4-3ubuntu3.1 library
for interfacing with different virtualization systems
un libvirt0-dbg <none> (no
description available)
ii python-libvirt 0.4.4-3ubuntu3.1 libvirt
Python bindings
un python2.5-libvirt <none> (no
description available)
ii ubuntu-virt-server 1.2 Common
packages necessary for hosting virtual machines
=====lspci for the ethernet controller
03:00.0 Ethernet controller: Broadcom Corporation NetXtreme II BCM5708 Gigabit
Ethernet (rev 12)
=====VM definition======================
<domain type='kvm'>
<name>VM0101</name>
<uuid>b59c3b25-0392-e94f-5283-a13b4162008f</uuid>
<memory>2097152</memory>
<currentMemory>2097152</currentMemory>
<vcpu>1</vcpu>
<os>
<type>hvm</type>
<boot dev='hd'/>
</os>
<features>
<acpi/>
</features>
<clock offset='utc'/>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>destroy</on_crash>
<devices>
<emulator>/usr/bin/kvm</emulator>
<disk type='block' device='disk'>
<source dev='/dev/VG0001/VM0101'/>
<target dev='hda' bus='ide'/>
</disk>
<interface type='bridge'>
<mac address='00:16:3e:5a:8b:b8'/>
<source bridge='br0'/>
<model type='virtio'/>
</interface>
<input type='mouse' bus='ps2'/>
<graphics type='vnc' port='-1' listen='localhost'/>
</devices>
</domain>
=====/etc/network/interfaces
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto eth0
iface eth0 inet manual
auto br0
iface br0 inet static
address [public ip]
netmask 255.255.255.128
network [network]
broadcast [broadcast]
gateway [gateway]
bridge_ports eth0
bridge_fd 9
bridge_hello 2
bridge_maxage 12
bridge_stp off
# dns-* options are implemented by the resolvconf package, if installed
dns-nameservers xxxxx yyyyy
dns-search datacenter.local
** Affects: ubuntu
Importance: Undecided
Status: New
** Tags: kvm libvirt
** Tags added: kvm libvirt
--
KVM network stops when starting second VM
https://bugs.launchpad.net/bugs/322794
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