It sounds like you have a good grasp of the in-band code. So, then, you should write up a patch with carefully written rationale and documentation updates and submit it to the dev list.
On Mon, Jul 08, 2013 at 09:35:03PM +0200, Andreas Brinner wrote: > I thought it would be obvious: > A switch behind an Open vSwitch trying to contact the controller has > to know the MAC address of the controller. Therefore the switch has > to send an ARP request to the controller to get the MAC address of > the controller as a reply. > That means, the Open vSwitch in between has to forward an ARP > request to the controller (dst mac = MAC of controller, dst ip = IP > of Controller, type=ARP request) and an ARP reply from the > controller (src mac = MAC of controller, src ip = IP of controller, > type=ARP reply). MAC and IP of the requesting switch can differ and > are unknown to the Open vSwitch in the first place. > > As I copied from the DESIGN paper: > >In the > >DESIGN guide the rules (d) and (e) are specified as follows: > > (d) ARP replies to the next hop's MAC address. > > (e) ARP requests from the next hop's MAC address. > > "the next hop" is, as far as I understand, the controller (or maybe > a gateway inbetween). That means, rules (d) and (e) are setting up > flows, so that the controller would be able to request (ARP request > from the next hop) the MAC address of any other network device and > can receive the answer (ARP replies to the next hop). > > That is just the wrong way! With this rules the OpenFlow switch > can't figure out the controller's MAC address and thus may never > contact it. The rules would have to be: > (d) ARP _requests_ to the next hop's MAC address. > (e) ARP _replies_ from the next hop's MAC address. > > > Cheers, > > Andreas > > > --On 8. Juli 2013 09:21:05 -0700 Ben Pfaff <b...@nicira.com> wrote: > > >On Fri, Jul 05, 2013 at 01:58:41AM +0200, Andreas Brinner wrote: > >>I was trying to cascadate an OpenFlow switch (Linksys with OpenWRT) > >>behind an Open vSwitch like this: > >>OF Switch (Linksys) <-> Open vSwitch <-> OF Controller > >> > >>I configured in-band mode for the Open vSwitch and I can see the > >>additional, hidden flow rules with ovs-appctl. But still the Linksys > >>couldn't connect to the controller. > >> > >>The reason was, that ARP requests from the Linksys were not > >>forwarded to the controller. > >> > >>So I had a look into the DESIGN paper and the in-band.c code. In the > >>DESIGN guide the rules (d) and (e) are specified as follows: > >> (d) ARP replies to the next hop's MAC address. > >> (e) ARP requests from the next hop's MAC address. > >>The exact same rules are set up by in-band.c and can be found in my > >>flow table. So atleast everything seems consistent here. > >> > >>Now my problem: these two rules should fire exactly in my case and > >>should enable my Linksys to retrive the MAC address of the OF > >>controller. At least if I understand the list of "supported" > >>scenarios correctly: > >> - Between Switch and Remote. This switch is between another > >> switch and the remote, and we want to allow the other > >> switch's traffic through. This uses rules (d), (e), (h), and > >> (i). It uses (b) and (c) indirectly in order to know the MAC > >> address for rules (d) and (e). > >> > >>But for this to work, rule (d) would have to allow ARP _requests_ to > >>the controler and (e) ARP _replies_ from the controller to pass! If > >>I manually add these rules to the flow table, the Linksys > >>successfully connects to the controller via the Open vSwitch. > >> > >>Do I miss anything here? > > > >Can you figure out why the flows set up by (d) and (e) aren't working > >for you? It sounds like they should. > > > > _______________________________________________ discuss mailing list discuss@openvswitch.org http://openvswitch.org/mailman/listinfo/discuss
