Date: Mon, 01 Jun 2009 20:03:57 +0200 From: Jedrzej Kalinowski <kalinoj1@iem.pw.edu.pl> To: Juergen Lock <nox@jelal.kn-bremen.de> Cc: freebsd-emulation@freebsd.org Subject: Re: Qemu: Assigning two tap devices to one virtual machine Message-ID: <4A24180D.1090006@iem.pw.edu.pl> In-Reply-To: <200906011636.n51GaCbJ007208@triton.kn-bremen.de>
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Juergen Lock pisze:
> In article <20090523223024.GA93488@volt.iem.pw.edu.pl> you write:
>> Hello all,
>>
>> I'm running qemu 0.10.5 on CURRENT machine and experienced an
>> interesting problem.
>>
>> I try to run a single qemu machine with two network interfaces (tap's)
>> connected to the same bridge - I need this for playing with m0n0wall for
>> example.
>>
>> The qemu launch looks similiar to this:
>>
>> qemu -net nic -net tap -net nic -net tap -cdrom cdrom.iso -curses
>>
>> What happens is that when qemu starts up - my machine locks (sometimes I
>> manage to kill qemu and recover it, sometimes not). I see that it's a
>> problem with network bridge - looks like the infitine loop of arp
>> requests that get replicated infinitely (it also kills/floods my real network
>> that is connected through the bridge to the tap devices).
>>
>> My question is - have any of You tried to use multiple tap devices within
>> one qemu machine? Can you replicate this problem in your environments?
>>
>> One note: there is no problem if I run two qemus and each of them has a
>> tap device connected to bridge0. They coexist and I have no network
>> issues in both guests. I can post qemu-if{up,down} scripts if needed.
>
> Ok just in case this hasn't been resolved yet...
>
> Try something like
> qemu -net nic -net tap -net nic,vlan=1,macaddr=52:54:00:12:34:57 -net tap,vlan=1 -cdrom cdrom.iso -curses
>
> and if you want you can also add `,model=e1000' to the -net nic parameters,
> that one (em(4) on FreeBSD) should perform a little better than the default
> ne2kpci (ed(4) on FreeBSD.)
>
> Explanation: vlan= is used to associate -net nic with -net tap/user/pcap
> connections (default is vlan=0), and macaddr= you need because qemu uses
> one single default macaddress (52:54:00:12:34:56 atm) for all -net nic
> and you can't have two nics with identical macs on the same network.
>
Yes, I tried it and I can confirm that it works well - assigning
different vlans to different nics saves the day here.
Also, good news is that qemu already doesn't create same MAC-addresses
for nics blindly. I run it like this:
qemu -net nic,model=e1000,vlan=0 -net user,vlan=0 -net
nic,model=e1000,vlan=1 -net user,vlan=1
And get:
(qemu) info network
VLAN 0 devices:
user.0:
e1000.0: model=e1000,macaddr=52:54:00:12:34:56
VLAN 1 devices:
user.1:
e1000.1: model=e1000,macaddr=52:54:00:12:34:57
> Good luck, :)
> Juergen
>
Thank you for your help, Juergen (and thanks for maintainig the port the
way it is always up to date with the latest release!)
Jędrzej Kalinowski
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