[ovs-dev] OVS Push VLAN Tag Hack and Problem

Naga Rohit, IIT Guwahati snagarohit at gmail.com
Thu May 24 05:40:32 UTC 2012


On Wed, May 23, 2012 at 9:31 PM, Ben Pfaff <blp at nicira.com> wrote:
> On Wed, May 23, 2012 at 11:44:58AM +0530, Naga Rohit, IIT Guwahati wrote:
>> Thanks for the quick response Mr Ben. However, I am bit confused on
>> which part of the code is responsible for the optimizations..
>
> I already told you: ofproto-dpif.c.

I am unable to find "ofproto-dpif.c" anywhere from the home directory
(/home/openflow/) (I am using mininet pre-installed VM).
Did you intend to refer to "ofproto.c" ?

>> FILE: ~/openvswitch/lib/dpif.c
>>
>> Guessing the functionality, I found "dpif_flow_put" to be probably
>> responsible for it. It is being called by "facet_put__" in
>> ~/openvswitch/ofproto/ofproto.c which is inturn being called by
>> "facet_install", "facet_revalidate" and "facet_active_timeout" Now,
>> where does optimizations happen ?
>
> Not in any of those functions.  In flow translation.

Please let me know which function is responsible for flow translation

>
>> Also, can you please let me know any way of specifying actions in
>> dpctl so that optimizations doesn't take place ?
>
> There is none, since it isn't useful to disable optimizations (unless
> you're trying to do something that OVS doesn't support, as you are).
>
>> Also, another strange thing I have found out is that when I commented
>> out "modify_vlan_tci" in ~/openvswitch/datapath/actions.c, it din't
>> throw up any error in make, install time and even at run time using
>> mininet (with ovsk switch and "dpctl
>> actions=mod_vlan_vid:xx,output:yy)
>
> You commented out something at random and expect us to tell you why
> what happened, happened?  I do not want to play that game.
>
> "ovsk"?

Yes, thats the way we invoke the open v switch from mininet isn't it ?
(I am using mininet and trying to add flows using dpctl tool and I am
running mininet using "--switch=ovsk" argument)

>
>> Thanks a lot,
>> Rohit
>>
>> On Wed, May 23, 2012 at 10:50 AM, Ben Pfaff <blp at nicira.com> wrote:
>> > On Wed, May 23, 2012 at 10:44:45AM +0530, Naga Rohit, IIT Guwahati wrote:
>> >> Where am I going wrong ? Does the changes I have made really result in
>> >> behavior that I intend to see ?
>> >
>> > Code in ofproto-dpif.c "optimizes out" actions that it considers
>> > redundant, including consecutive changes to the VLAN without an
>> > intervening output action.
>> _______________________________________________
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Thank you again for your kind reply :-)

-Rohit



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