Re: [Qemu-devel] Re: Network bridging without adding bridge with brctl, possible?

[Jan Kiszka <jan.kiszka@web.de>]

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On 2011-02-20 13:49, Gerhard Wiesinger wrote:
> On Sun, 20 Feb 2011, Jan Kiszka wrote:
> 
>> On 2011-02-19 20:32, Gerhard Wiesinger wrote:
>>> Hello,
>> http://virt.kernelnewbies.org/MacVTap
>>
>>    ip link add link eth1 name macvtap0 type macvtap mode bridge
>>    ip link add link eth1 name macvlan0 type macvlan mode bridge
>>    ifconfig macvlan0 ...
> 
> 
> Hello Jan,
> 
> iproute2 2.6.37 is needed!
> http://devresources.linuxfoundation.org/dev/iproute2/download/iproute2-2.6.37.tar.bz2
> 
> ==================================================================================
> 
> 1.) Only macvtap interface used
> ==================================================================================
> 
> For me it was just unlogically to use a VLAN type interface. Therefore I
> tried the following which worked nearly:
> /root/download/iproute2/iproute2-2.6.37/ip/ip link add link eth0 name
> macvtap0 type macvtap mode bridge
> /root/download/iproute2/iproute2-2.6.37/ip/ip link set macvtap0 address
> 1a:46:0b:ca:bc:7b up
> ip link show macvtap0
> ls -l /dev/tap*
> # crw-rw---- 1 root root 249, 8 Feb 20 13:07 /dev/tap8
> qemu-system-x86_64 ... some params ... -net
> nic,model=e1000,macaddr=1a:46:0b:ca:bc:7b -net tap,fd=3 3<>/dev/tap8
> 
> Booting Knoppix 6.2 with ping is ok, MAC address is also correct on
> second host.
> 
> Only problem is that from host to guest no networking is possible (only
> from guest to other host).
> 
> Any ideas? I guess some forwarding is missing? iptables forward missing?

To my understanding macvlan(+macvtap) devices in bridge mode can only
talk to the outer world via the physical device they are attached to or
other macvlan nodes attached to that same device. Therefore...

> ==================================================================================
> 
> 2.) Only macvtap interface used
> ==================================================================================
> 
> /root/download/iproute2/iproute2-2.6.37/ip/ip link add link eth0 name
> macvtap0 type macvtap mode bridge
> /root/download/iproute2/iproute2-2.6.37/ip/ip link set macvtap0 address
> 1a:46:0b:ca:bc:7b up
> #/root/download/iproute2/iproute2-2.6.37/ip/ip link add link eth0 name
> macvlan0 type macvlan mode bridge
> #/root/download/iproute2/iproute2-2.6.37/ip/ip link set macvlan0 address

...the need for this additional macvlan device. You just have to set an
IP on macvlan0.

Jan

> 1a:46:0b:ca:bc:7c up
> ip link show macvtap0
> ip link show macvlan0
> ls -l /dev/tap*
> # crw-rw---- 1 root root 249, 8 Feb 20 13:07 /dev/tap8
> # No further TAP device created! (Reason why it doesn't work?)
> # 7c MAC is used!?
> qemu-system-x86_64 ... some params ... -net
> nic,model=e1000,macaddr=1a:46:0b:ca:bc:7c -net tap,fd=3 3<>/dev/tap8
> 
> Booting Knoppix 6.2 without any networking, eth0 in guest has 7c MAC
> address.
> 
> Any ideas?
> ==================================================================================
> 
> 
> Thnx.
> 
> Ciao,
> Gerhard
> 
> -- 
> http://www.wiesinger.com/
> 


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