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

[Gerhard Wiesinger <lists@wiesinger.com>]

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?

Thnx.

Ciao,
Gerhard

--
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