From: arnd@arndb.de
To: J L <lists@rrod.net>
Cc: kvm@vger.kernel.org
Subject: Re: Multiple TAP Interfaces, with multiple bridges
Date: Wed, 3 Feb 2010 18:16:01 +0100 [thread overview]
Message-ID: <201002031816.02035.arnd@arndb.de> (raw)
In-Reply-To: <15f314a41002030856o70066267pc2e8f2b768fd3d83@mail.gmail.com>
On Wednesday 03 February 2010 17:56:43 J L wrote:
> I am having an odd networking issue. It is one of those "it used to
> work, and now it doesn't" kind of things. I can't work out what I am
> doing differently.
>
> I have a virtual machine, started with (among other things):
> -net nic,macaddr=fa:9e:0b:53:d2:7d,model=rtl8139 -net
> tap,script=/images/1/ifup-eth0,downscript=/images/1/ifdown-eth0
> -net nic,macaddr=fa:02:4e:86:ed:ce,model=e1000 -net
> tap,script=/images/1/ifup-eth1,downscript=/images/1/ifdown-eth1
This seems to be missing a vlan= option at least for the second pair:
> What I actually get:
> * VM: eth1, dest MAC of Host's tap1/br0
> * Host: tap1, dest MAC of Host's tap1/br0
> * Host: br1, dest MAC of Host's tap1/br0
> * Host should, but does not route from br0 to br1
> * Host: tap0, dest MAC of ***Host's tap1/br0***
> * Host: br0, dest MAC of ***Host's tap1/br0**
> * Host: eth0, no packet
> * Server: eth0, no packet
>
> As you can see, the packet has egressed both tap interfaces! Is this
> expected behaviour? What can I do about this?
Qemu forwards this packet to everything inside of the same vlan, which
is 0 by default. Does it work with this?
-net nic,vlan=1,macaddr=fa:9e:0b:53:d2:7d,model=rtl8139 -net tap,vlan=1,script=/images/1/ifup-eth0,downscript=/images/1/ifdown-eth0
-net nic,vlan=2,macaddr=fa:02:4e:86:ed:ce,model=e1000 -net tap,vlan=2,script=/images/1/ifup-eth1,downscript=/images/1/ifdown-eth1
> If I remove tap0 from the bridge, I then get:
> * VM: eth1, dest MAC of Host's tap1/br0
> * Host: tap1, dest MAC of Host's tap1/br0
> * Host: br1, dest MAC of Host's tap1/br0
> * Host should, but does not, route from br0 to br1
> * Host: tap0, no packet
> * Host: br0, no packet
> * Host: eth0, no packet
> * Server: eth0, no packet
>
> This is the other half of my problem: in this case, with effectively
> only one tap, the host is not routing between br1 and br0. The packet
> just gets silently dropped. Does anyone know what I am doing wrong?
Maybe /proc/sys/net/ipv4/ip_forward is disabled?
Arnd
next prev parent reply other threads:[~2010-02-03 17:16 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-03 16:56 Multiple TAP Interfaces, with multiple bridges J L
2010-02-03 17:10 ` Tom Lendacky
2010-02-03 17:16 ` arnd [this message]
2010-02-03 17:44 ` J L
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