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 16:19, Gerhard Wiesinger wrote:
> On Sun, 20 Feb 2011, Jan Kiszka wrote:
> 
>> 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.
> 
> Negative.
> 
> Tried:
> /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
> 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, 10 Feb 20 15:45 /dev/tap10
> ifconfig macvlan0 192.168.0.23 up
> 
> DHCP is configure for 1a:46:0b:ca:bc:7b mac for 192.168.0.23 ip and
> 1a:46:0b:ca:bc:7c mac for 192.168.0.24 ip.
> 
> # works without outer connection
> qemu-system-x86_64 ... some params ... -net
> nic,model=e1000,macaddr=1a:46:0b:ca:bc:7b -net tap,fd=3 3<>/dev/tap10
> 
> # 2nd try:
> ifconfig macvlan0 192.168.0.24 up
> # No network at all
> qemu-system-x86_64 ... some params ... -net
> nic,model=e1000,macaddr=1a:46:0b:ca:bc:7c -net tap,fd=3 3<>/dev/tap10
> 
> Seems to me quite logically because macvtap0 (and not macvlan0) is
> associated with /dev/tap10 but with another mac address set in KVM.
> 
> Any furher ideas?

As you already noticed: you mixed up the MAC addresses. KVM's must be
the same as used for its frontend macvtap. The macvlan is only for the
host and has a separate one.

Jan


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