Re: [Qemu-discuss] Host-Bridge in routed TAP Mode

[Vlad Yasevich]

On 09/25/2013 09:59 AM, Sven Gehr wrote:
> address@hidden,
>
> I'm use KVM on a Ubuntu Server 12.04 LTS 64 Bit and I try to configure the
> bridge completely with libvirt.
>
> The Device eth0 is connected to the lan (192.168.100.0/24)
>
> I generate the file /etc/libvirt/qemu/networks/intern.xml to specify my
> network 'intern'
>
> <network>
>    <name>intern</name>
>    <uuid>77b879fa-4c04-0cb2-e58a-aef0673806a4</uuid>
>    <forward dev='eth0' mode='route'/>
>    <bridge name='intern' stp='on' delay='0' />
>    <mac address='52:54:00:8F:05:DB'/>
>    <ip address='192.168.100.1' netmask='255.255.255.0'>
>    </ip>
> </network>
>
> and mark it 'autostart'
>
>
> My /etc/network/interfaces looks like this:
>
> # The loopback network interface
> auto lo
> iface lo inet loopback
>
>
> # eth0 ohne IP für Bridge Variante 1
> auto eth0
> iface eth0 inet manual
>    up ifconfig eth0 0.0.0.0 promisc up
>
>
> I reboot the system ....
>
>
> ifconfig show me:
>
> address@hidden:~# ifconfig
> eth0      Link encap:Ethernet  Hardware Adresse 68:05:ca:0f:81:2c
>            inet6-Adresse: fe80::6a05:caff:fe0f:812c/64
> Gültigkeitsbereich:Verbindung
>            UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metrik:1
>            RX packets:192 errors:0 dropped:0 overruns:0 frame:0
>            TX packets:228 errors:0 dropped:0 overruns:0 carrier:0
>            Kollisionen:0 Sendewarteschlangenlänge:1000
>            RX-Bytes:22033 (22.0 KB)  TX-Bytes:24529 (24.5 KB)
>            Interrupt:18 Speicher:fcfc0000-fcfe0000
>
> intern    Link encap:Ethernet  Hardware Adresse 52:54:00:8f:05:db
>            inet Adresse:192.168.100.1  Bcast:192.168.100.255
> Maske:255.255.255.0
>            UP BROADCAST RUNNING MULTICAST  MTU:1500  Metrik:1
>            RX packets:172 errors:0 dropped:0 overruns:0 frame:0
>            TX packets:104 errors:0 dropped:0 overruns:0 carrier:0
>            Kollisionen:0 Sendewarteschlangenlänge:0
>            RX-Bytes:14661 (14.6 KB)  TX-Bytes:16033 (16.0 KB)
>
> lo        Link encap:Lokale Schleife
>            inet Adresse:127.0.0.1  Maske:255.0.0.0
>            inet6-Adresse: ::1/128 Gültigkeitsbereich:Maschine
>            UP LOOPBACK RUNNING  MTU:65536  Metrik:1
>            RX packets:20 errors:0 dropped:0 overruns:0 frame:0
>            TX packets:20 errors:0 dropped:0 overruns:0 carrier:0
>            Kollisionen:0 Sendewarteschlangenlänge:0
>            RX-Bytes:1536 (1.5 KB)  TX-Bytes:1536 (1.5 KB)
>
>
>
> and:
>
>
> address@hidden:~# brctl show
> bridge name     bridge id               STP enabled     interfaces
> intern          8000.5254008f05db       yes             intern-nic
>
> The problem is that eth0 was not bound to the bridge 'intern' intern.
>
>
>
> When I add eth0 manually it will work and I can ping the host from the lan
>
>
> address@hidden:~# brctl addif intern eth0
> [...]
> address@hidden:~# brctl show
> bridge name     bridge id               STP enabled     interfaces
> intern          8000.5254008f05db       yes             eth0
>                                                          intern-nic
>
>
> but why it is not automatically added by this line:


From what I understand, routed mode is just that.  It depends
on ip forwarding being enabled for the interfaces and it will
try to route the packets from your bridge out through your designated
interface.

What you seem to be looking for is a bridged configuration where
you connect the physical nic and virtial nic to the same bridge.
I don't see libvirt support that in their virtual network config.
You can used libvirt to setup a bridged interface in the Network 
Interfaces tab though.

-vlad
> <forward dev='eth0' mode='route'/>
>
> ??