Re: VM networking stops working

[Mike <mike-kcIQ9yavhvsV/sYkb9DZNQ@public.gmane.org>]

Lynn Kerby schrieb:
>
> On Nov 21, 2007, at 12:52 PM, 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
>
> I had similar problems for my first week or so of trying to use KVM 
> for my virtualization needs.  My problem was solved by adding a 
> "model=rtl8139" to the first -net option on the kvm/qemu command.  The 
> default ne2k emulation seems to be broken.  Another possibility is 
> problems with macaddr.  In my testing I found that several of my 
> machines were getting the same macaddr by default so now I specify 
> them explicitly for each VM (or generate a dummy one based on the time 
> for testing).
>
> An example from one of my KVMMs (hopefully line wrapping won't 
> interfere):
>
> /usr/local/bin/qemu-system-x86_64 -name DOM9-BSD62 -hda 
> /vm_img/bsd_in1/dom9-disk1.qcow \
>     -hdb /vm_img/bsd_in1/dom9-disk2.raw -m 512 -boot c -smp 2 -usb 
> -usbdevice tablet -vnc :9 \
>     -serial telnet::4109,server,nowait -monitor 
> telnet::4209,server,nowait \
>     -net nic,vlan=0,macaddr=52:54:09:12:34:56,model=rtl8139 \
>     -net tap,vlan=0,ifname=tap1,script=/etc/kvm/kvm-ifup
>
>
> Lynn Kerby
>
It's working now.
I added model=rtl8139 to the start command of all vms.
Now, the network connection works without problems.
I did a test the whole night long.
Thank you for your help.

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