[ovs-discuss] 回复: a question regarding to tap internal interface

Ben Pfaff blp at ovn.org
Mon Mar 18 20:32:22 UTC 2019


I think that "tap" is just the name of the interface in that case.  I
don't know why it is named "tap".

On Sat, Mar 16, 2019 at 11:27:21PM +0000, pei Jikui wrote:
> Ben,
> 
> Thanks much for your reply.
> 
> My confusion comes from the openstack's official document of https://docs.openstack.org/liberty/networking-guide/scenario-classic-ovs.html
> 
>    As illustrated in the picture, we can see that the interface used to connect ovs and dhcp-netns is a tap interface. While from the output of "ovs-vsctl show", it indicates that the type of interface is internal.  That confuses me much.
> 
>    I am thinking that the tap interface is for the name of the interface instead of the type of the interface?
> 
> Thanks
> 
> 
> 
> 
> 
> 
> 
> 
> 发送自 Outlook<http://aka.ms/weboutlook>
> 
> ________________________________
> 发件人: Ben Pfaff <blp at ovn.org>
> 发送时间: 2019年3月17日 1:44
> 收件人: pei Jikui
> 抄送: ovs-discuss at openvswitch.org
> 主题: Re: [ovs-discuss] a question regarding to tap internal interface
> 
> On Sat, Mar 16, 2019 at 11:24:34AM +0000, pei Jikui wrote:
> > hi,
> >
> > 1) From the openstack documents, we know that for the tenant's dhcp functionality, the usage is to connect a dhcp netns to the ovs using a tap interface.
> > At the same time, the ovs-vsctl show that the tap interface is a type of internal interface for OVS.
> 
> This is wrong.  Tap and internal are different kinds of interfaces.
> What does ovs-vsctl show that makes you confuse the two?
> 
> > While I could not add a tap type interface to ovs as an internal type of interface for OVS.
> >
> > The commands I used,
> > a) ip tuntap add dev tap0 mode tap.
> > b) ovs-vsctl add-port ovs0 tap0 -- set inteface tap0 type=internal
> 
> These commands are wrong.  If you create a tap interface, you must not
> tell ovs-vsctl that it is an internal interface.
> 
> What led you to believe that these commands were correct?
> 
> > error: "could not add network device tap12 to ofproto (No such device)"
> >
> > 2) My questions are ,
> >    a) how to add a tap interface to OVS and set it as internal type of interface of OVS?
> 
> You cannot.  That is not possible.




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