I drew a little ascii art, does this clarify things?
Hypervisor
+--------------------------------------------------------+
| |
+------ | -- iface <--------------------------------------+ |
| | eth0 | |
| | | |
{network} | | |
| | v |
| | |
+------ | -- iface <-------------------------------> {IP stack} |
| eth1 |
| ^ |
| bridge br0 | |
| +---+ | |
| | | (internal) | |
| | +-- port -- iface -------+ |
| | | br0 br0 |
| | | |
| | | VM 1 |
| | | +-----+ |
| | +-- port -- iface -- | | |
| | | tap1 tap1 +-----+ |
| | | |
| | | VM 2 |
| | | +-----+ |
| | +-- port -- iface -- | | |
| | | tap2 tap2 +-----+ |
| +---+ |
| |
+---------------------------------------------------------+
******************************************
* user@host$ ovs-vsctl add-port br1 eth1 *
******************************************
Hypervisor
+--------------------------------------------------------+
| |
+------ | -- iface <--------------------------------------+ |
| | eth0 | |
| | | |
{network} | | |
| | v |
| | |
+------ | -- iface <---+ X------------------------> {IP stack} |
| eth1 | |
| | ^ |
| | bridge br1 | |
| | +---+ | |
| v | | (internal) | |
| port --+ +-- port -- iface <------+ |
| eth1 | | br1 br1 |
| | | VM 1 |
| | | +-----+ |
| | +-- port -- iface -- | | |
| | | tap1 tap1 +-----+ |
| | | |
| | | VM 2 |
| | | +-----+ |
| | +-- port -- iface -- | | |
| | | tap2 tap2 +-----+ |
| +---+ |
| |
+---------------------------------------------------------+
Non-Effects:
IP configuration of eth1 is unchanged
IP configuration of br0 is unchanged
Routing table is unchanged
Effects:
Traffic routed to eth1 by the IP stack will be blackholed, since it is now
attached to port eth1
Traffic routed to br0 by the IP stack has eth1 as a potential egress port
Usual Correction:
Move IP configuration of eth1 to br1
Remove IP configuration from eth1
Effects:
If bridge br1 is in 'standalone' mode:
- eth1's old IP is reachable from the network
- VM 1 and VM 2 are reachable from the network (and would see eth1's
traffic as well)
On Fri, May 18, 2012 at 7:19 AM, Salman Malik <[email protected]> wrote:
> Thanks Robin and Reid. Its still a little fuzzy to me. Can you suggest
> some pointers which explains the bridge and related interfaces
> configuration ?
> I have worked for some time with ovs and integration bridge (that ovs
> manages) and I couldn't get my head around the routing mechanism e.g. doing
> an ifconfig would show all the interfaces like br100 and eth1. So is bridge
> an interface or an emulation of a real bridge ? (because I could see a
> HWaddress associated with this bridge/interface... and for some reason I
> think that each port of real bridge should have a MAC/IP associated with
> it, but I don't know). And when we add interface eth1 to br100 as a port, I
> understand that all the VM traffic would now go through eth1 (acting as an
> uplink, and conveying traffic from bridge to real switch and the VMs
> themselves can get the IP address in the same subnet as host itself,
> right?), but I can't visualize the scenario, given the output of ifconfig,
> brctl show or ovs-vsctl show/ ovs-ofctl show br100.
>
> Any explanation is much appreciated.
>
> Thanks,
> Salman
>
>
> ------------------------------
> CC: [email protected]; [email protected]
> From: [email protected]
>
> Subject: Re: [ovs-discuss] why vm can't ping host eth1
> Date: Thu, 17 May 2012 22:31:08 -0700
> To: [email protected]
>
>
> One thing I have seen in the past: if ethX has an ip as well as brX, it
> usually means that routing will try to send traffic out ethX. That traffic
> will be dropped, since brX is now the one hooked up to the ip stack (not
> ethX).
>
> On May 17, 2555 BE, at 20:49, Robin Wang <[email protected]> wrote:
>
> eth1, sorry for typo mistake.
> 在 2012-5-18 上午11:48，"Robin Wang" < <[email protected]>
> [email protected]>写道：
>
> Because uplink doesn't need IP address. Here eth0 is used to connect two
> switches, one virtual, one physical. Thanks.
> 在 2012-5-18 上午10:49，"Salman Malik" < <[email protected]>[email protected]
> >写道：
>
> Hi Dongsheng,
>
> Could you please tell me, why do we need to clear up the eth1 IP address?
> Does it interfere with the bridge ? If yes then how ?
> Bridge management is a bit unclear to me so thats why I am asking.
>
> Thanks,
> Salman
>
>
> > From: <[email protected]>[email protected]
> > Date: Fri, 18 May 2012 10:32:23 +0800
> > To: <[email protected]>[email protected]
> > CC: <[email protected]>[email protected]
> > Subject: Re: [ovs-discuss] why vm can't ping host eth1
> >
> > On Thu, May 17, 2012 at 7:12 PM, yue wang < <[email protected]>
> [email protected]> wrote:
> > >
> > > i think vm1/vm2/host are connected to each other by OVS, vm and host
> should communicate with each other.
> >
> > Sure, please see another thread:
> > <http://openvswitch.org/pipermail/discuss/2012-May/007201.html>
> http://openvswitch.org/pipermail/discuss/2012-May/007201.html
> >
> > You must clean ALL ip address on eth1, and set the ip address on the
> > corresponding bridge device,
> > say 'br1', here is a example:
> >
> > /usr/bin/ovs-vsctl add-br br1
> > /usr/bin/ovs-vsctl add-port br1 eth1
> >
> > /sbin/ip addr add ${IP} dev br1
> > /sbin/ip link set br1 up
> > /sbin/ip address flush dev eth1
> > /sbin/ip route replace default via ${GW} # if you have gateway
> > corresponding eth1
> > _______________________________________________
> > discuss mailing list
> > <[email protected]>[email protected]
> > <http://openvswitch.org/mailman/listinfo/discuss>
> http://openvswitch.org/mailman/listinfo/discuss
>
> _______________________________________________
> discuss mailing list
> <[email protected]>[email protected]
> <http://openvswitch.org/mailman/listinfo/discuss>
> http://openvswitch.org/mailman/listinfo/discuss
>
> _______________________________________________
> discuss mailing list
> [email protected]
> http://openvswitch.org/mailman/listinfo/discuss
>
>
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