[ovs-discuss] in-band mode
Andreas Brinner
andreas at brinner.de
Thu Jul 4 23:58:41 UTC 2013
Hello,
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?
Cheers,
Andreas
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