[ovs-discuss] Question about a vm connect to 2 bridges?

Jesse Gross jesse at nicira.com
Mon Aug 8 02:15:53 UTC 2011


2011/8/8 changlimin <changlimin at h3c.com>:
> Hi,
>
>     I start a ovs-vswitchd, then create 2 bridges: br0 and br1.
>
>     Then I start a vm, which has 2 vnics, the mac is 00:00:01:00:00:01,
> 00:00:02:00:00:01, connect to br0 and br1 respective.
>
>     # kvm -name vm0 -m 384 -hda /images/1.img -vnc :0 \
>      -net nic,macaddr=00:00:01:00:00:01 -net
> tap,script=/etc/ovs-ifup,downscript=/etc/ovs-ifdown \
>      -net nic,macaddr=00:00:02:00:00:01 -net
> tap,script=/etc/ovs-ifup1,downscript=/etc/ovs-ifdown1 &
>     # cat /etc/ovs-ifup
>         switch='br0'
>         /sbin/ifconfig $1 0.0.0.0 up
>         ovs-vsctl add-port ${switch} $1 tag=10
>     # cat /etc/ovs-ifup1
>         #!/bin/sh
>         switch='br1'
>         /sbin/ifconfig $1 0.0.0.0 up
>         ovs-vsctl add-port ${switch} $1 tag=11
>
>     Then I find something strange:
>
>     # ovs-appctl fdb/show br0
>      port  VLAN  MAC                Age
>         1    10  7a:e0:56:ae:1d:c9  529
>         1    10  00:00:02:00:00:01  182        The nic connect br1, why
> appear at br0 ?
>         1    10  00:00:01:00:00:01  182
>     # ovs-appctl fdb/show br1
>      port  VLAN  MAC                Age
>         1    11  12:93:1d:8e:7d:74  536
>         1    11  00:00:02:00:00:01  183
>         1    11  00:00:01:00:00:01  183        The nic connect br0, why
> appear at br1 ?
>     Does there is a implict cable connect br0 to br1 ?

KVM has an internal set of "vlans" that by default are all the same.
Unless you assign interfaces to different vlans in KVM you will get
crosstalk.


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