[ovs-dev] lookups in OVS data path

SDN learn sdn.learn at gmail.com
Fri Feb 1 10:19:25 UTC 2013

Hello OVS experts,

I'm new to OVS and trying to understand a few things...

1. When packet comes in, there is a lookup for outer-IP/L4 in vport-gre.c
(for GRE overlay). Then GRE key is matched.
Finally, at some point later, there is a look up for inner IP/L4 before
inner IP/L4/payload is sent to "action" port.
Is that correct? If yes, why do we need multi stage lookup policies? Isn't
that inefficient...any issues in combining them into a single wider lookup?

2. When OVS terminates outer-IP/overlay header etc, the inner-IP+payload is
sent to hypervisor...how does the hypervisor associate this packet to a
particular Virtual-Machine instance.
Does OF controller select a different "action" port for each VM?

Thanks for your thoughts...
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