[ovs-discuss] how can 2 ports in different bridge communicate?

[Ben Pfaff]

On Mon, Sep 29, 2014 at 09:39:21AM +0800, ychen wrote:
>   Thanks very much, the information really helps.
>   What I am confused is about GRE  tunnel
>   http://blog.scottlowe.org/2013/05/07/using-gre-tunnels-with-open-vswitch/
>   In the above blog, each host uses two bridges, one for GRE, one for physical port 
>   but there seems no patch port between 2 bridges.

I think that the presence of two bridges in this configuration is a red
herring.  The way that packets make it from the GRE tunnel into the
second bridge in this scenario is the same way that packets make it from
a GRE tunnel into a bridge when there is only one bridge.  If you are
setting up a GRE tunnel with Open vSwitch for the first time, then it is
probably easiest to just use one bridge (and keep the physical device
off that bridge).