[ovs-discuss] OVS vlan tag and dl_vlan in the flow entry

Hong Wayne wayne21205 at gmail.com
Fri Feb 8 18:58:51 UTC 2013


Dear Ben:


OK, my orginal question is when I command:
# ovs-ofctl dump-flows br-int

I see the flow entries in flow table, and the field dl_vlan default is 0.

1. If I use OpenFlow Controller to modify the value of dl_vlan field to 15,
does it means that it will match the packets which packet the vlan tag is
15?

2. On the other OVS, I only see the field vlan_tci which is related to
VLAN, what's the difference between dl_vlan and vlan_tci?

3. What's the situation that I need to use OpenFlow Controller to add the
action field with OFPAT_SET_VLAN_VID?

Sorry to trouble you to resolve my questions, thanks.


2013/2/9 Ben Pfaff <blp at nicira.com>

> I think I gave a complete explanation before, can you ask a more
> specific question?
>
> On Sat, Feb 09, 2013 at 12:59:23AM +0800, Hong Wayne wrote:
> > Hi Ben:
> >
> >
> > Thanks for your replying.
> >
> > After my test, when I set two Open vSwitch with VLAN using ovs-vsctl
> > command like below:
> >
> > OVS1:
> > #sudo ovs-vsctl add-port br-int eth1 trunks=15
> > #sudo ovs-vsctl add-port br-int vnet0_1 tag=15 (VM1)
> >
> > OVS2:
> > #sudo ovs-vsctl add-port br-int eth1 trunks=15
> > #sudo ovs-vsctl add-port br-int vnet0_2 tag=15 (VM2)
> >
> > And I connect two of trunk ports(eth1) using physical wire. Two of OVS
> all
> > connect to POX Controller.
> >
> > In my case when VM1 ping VM2, Do I need to add the VLAN tag through the
> > Controller with mod_vlan_vid and strip the VLAN tag with strip_vlan when
> > packet come back?
> >
> > Sorry, I got some confused about the VLAN setting.
> >
> >
> >
> > 2013/2/7 Ben Pfaff <blp at nicira.com>
> >
> > > On Wed, Feb 06, 2013 at 08:11:45PM +0800, Hong Wayne wrote:
> > > > I already read the FAQ before, but my doubt is about the difference
> > > between
> > > > dl_vlan in flow entry and the vlan tag using by ovs-vsctl command.
> > > >
> > > > In FAQ (Q: My OpenFlow controller doesn't see the VLANs that I
> expect.)
> > > >
> > > > The sentences for ''But, if you set up OpenFlow flows on your own,
> > > through
> > > > a controller or using ovs-ofctl or through other means, then you
> have to
> > > > implement VLAN handling yourself.''
> > > >
> > > > Does it means the way to ''set dl_valn field'' through Controller or
> > > > commands? So I need to modify the action field to "normal" into the
> lists
> > > > of actions to take dl_vlan effect?
> > >
> > > If a packet comes in on an access port, and the flow table needs to
> send
> > > it out on a trunk port, then the flow will need to add the VLAN tag
> with
> > > mod_vlan_vid.  Conversely, if a packet comes in on a trunk port, and
> the
> > > flow table needs to send it out on an access port, then the flow will
> > > need to strip the VLAN tag with strip_vlan.
> > >
>
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