Re: VM networking stops working

[Izik Eidus <izike-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Mike wrote:
> Hello,
> I have a problem with my virtual machines. I am using kvm53
> on an AMD Athlon(tm) 64 X2 Dual Core Processor 5000+.
> As distribution I use Ubuntu server 7.10.
> As kernel I use Linux 2.6.22-14-server #1 SMP Sun Oct 14 22:09:15 GMT 
> 2007 x86_64 GNU/Linux.
>
> I have 3 different vms running. At the beginning they all work without 
> a problem.
> Then, after one moment to another one or more stop working.
> I did a ping test to all the machines, the vm with the failure stops 
> pinging.
> The result from external ping: Destination host unreachable.
> The same result from a ping onto the main server.
>
> Here are my configuration files:
> cat /etc/qemu-ifup
> #!/bin/sh
> /sbin/ifconfig $1 0.0.0.0 promisc up
> /usr/sbin/brctl addif br0 $1
> sleep 2
> ------------------------------------------------------------------------
> cat /etc/network/interfaces
> auto lo
> iface lo inet loopback
>
> auto br0
> iface br0 inet static
> address 195.24.77.169
> netmask 255.255.255.0
> gateway 195.24.77.1
> bridge_ports eth0
> bridge_stp off
> bridge_maxwait 5
> ------------------------------------------------------------------------
> I use scripts for starting the vms:
> kvm -hda apache.img -hdb apache_storage.img -m 512 -boot c -net 
> nic,vlan=0,macaddr=00:16:3e:00:00:01 -net tap -nographic -daemonize
> kvm -hda postfix.img -m 512 -boot c -net 
> nic,vlan=0,macaddr=00:16:3e:00:00:12 -net tap -nographic -daemonize
> kvm -hda openvpn.img -m 256 -boot c -net 
> nic,vlan=0,macaddr=00:16:3e:00:00:03 -net tap -nographic -daemonize
> ------------------------------------------------------------------------
> The tapN devices are being created at the startup of the vms.
>
> When I run dmesg I have this:
> [  112.390943] br0: port 2(tap1) entering learning state
> [  112.391919] br0: port 3(tap0) entering learning state
> [  112.397605] br0: port 4(tap2) entering learning state
> [  122.674313] tap0: no IPv6 routers present
> [  122.729185] tap1: no IPv6 routers present
> [  122.843901] tap2: no IPv6 routers present
> [  123.336081] kvm: emulating exchange as write
> [  127.367940] br0: topology change detected, propagating
> [  127.367949] br0: port 4(tap2) entering forwarding state
> [  127.362971] br0: topology change detected, propagating
> [  127.362977] br0: port 2(tap1) entering forwarding state
> [  127.362978] br0: topology change detected, propagating
> [  127.362980] br0: port 3(tap0) entering forwarding state
>
> No indication of a problem, nowhere in the log files.
>
> I don't know if the vms are freezing, or the network forwarding stops 
> working.
> I also activated "net.ipv4.conf.default.forwarding=1"
>
> I googled days for that problem, but without a result.
> I hope that maybe you have a solution for this problem. That would be 
> great, because I prefer using kvm instead of other virtualization systems.
>
> Thank you very much in advance,
> Greetings from Luxembourg.
>
> Have a nice day,
> Mike
it might be not the network that die, but the whole vm
can you run the vms with -vnc ? (first vm -vnc :1 secoend vm -vnc :2 
third vm -vnc :3)
and try to connect to them with vncviewer and see if they are alive?

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