Hi,

The ofprotocol in the reference switch is more than just a relayer process. If 
I remember correctly it
also deals with in-band control and port status handling. For this latter 
feature it needs to know
what ports were assigned to the datapath, and might use a feature request of 
its own.

Regards,
Zoltan.

> -----Original Message-----
> From: nox-dev-boun...@noxrepo.org 
> [mailto:nox-dev-boun...@noxrepo.org] On Behalf Of Cayle Spandon
> Sent: Friday, January 13, 2012 1:36 PM
> To: Murphy McCauley
> Cc: nox-dev@noxrepo.org
> Subject: Re: [nox-dev] features-reply without features-request
> 
> Hi Murphy,
> 
> Thanks for the reply.
> 
> No, I am not using NOX (Yes indeed - I should have gone to 
> the OpenFlow mailing list. I will.).
> 
> This is a new controller which is still under development. I 
> am sure the controller does not send a features-request 
> (because that part has not been coded yet). So, yes, the 
> controller is "out of spec" for now.
> 
> So I am sure that the features request comes from 
> "ifprotocol" (which is not a controller, as far as I know). 
> It appears to send it "proactively" as you say, and this is 
> exactly what seemed surprising (and frankly incorrect) to me.
> 
> Also, I am using the OpenFlow dissector in wireshark, so I 
> quite sure that the list of packets is accurate in the 
> summary below (i.e. I did not miss packets because there 
> multiple OpenFlow packets in a single TCP packet).
> 
> On Wed, Jan 11, 2012 at 3:59 PM, Murphy McCauley 
> <jam...@nau.edu> wrote:
> > I can't speak as to the particulars of the reference switch 
> (you might try one of the OpenFlow mailing lists).
> >
> > However, the spec does state that part of the handshake 
> sequence is that the controller sends a features request when 
> a connection is established.  I don't see this in your 
> sequences of messages below.  NOX should do this.  Are you 
> using NOX?  If so, is it possible you missed this message 
> (remember that multiple OpenFlow messages can be in the same 
> packet, so it is possible it's in packet #4 along with the 
> HELLO or something -- you'll have to look at the detail view 
> of the packet, not just the summary line)?
> >
> > If the message really isn't there, I suppose it's possible 
> that ofprotocol does this proactively, but in this case I 
> believe your controller is out of spec.
> >
> > -- Murphy
> >
> > On Jan 11, 2012, at 6:00 AM, Cayle Spandon wrote:
> >
> >> Are OpenFlow controllers expected to process unsolicited 
> feature-reply messages?
> >>
> >> I am running the following setup:
> >>
> >> controller ----- ofprotocol ----- ofdatapath
> >>
> >> Using wireshark I see the following sequence of messages:
> >>
> >> #1 ofprotocol -> ofdatapath : hello
> >> #2 ofprotocol -> controller : hello
> >> #3 ofdatapath -> ofprotocol : hello
> >> #4 controller -> ofprotocol : hello
> >> #5 ofprotocol -> ofdatapath : features-request
> >> #6 ofdatapath -> ofprotocol : features-reply
> >> #7 ofprotocol -> controller : features-reply
> >>
> >> This means that the controller gets a features-reply even 
> though it 
> >> never sent a features-request.
> >>
> >> It appears that ofprotocol originates the features-request to the 
> >> switch (which is somewhat surprising because I thought it was 
> >> supposed to be a dumb pass-through) and the forwards the 
> >> features-reply to the controller.
> >> _______________________________________________
> >> nox-dev mailing list
> >> nox-dev@noxrepo.org
> >> http://noxrepo.org/mailman/listinfo/nox-dev
> >
> _______________________________________________
> nox-dev mailing list
> nox-dev@noxrepo.org
> http://noxrepo.org/mailman/listinfo/nox-dev
> 
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