[ovs-discuss] OVS -- Linux interaction

[Abhishek Verma]

Hi,

I have an OVS bridge in which i have added an eth0 and an eth1 port. I am
receiving some traffic on eth1 and am sending it out on a VXLAN tunnel that
goes out over eth0.

My question is this:

For the packet to eventually go out, the outer L2 header must be populated.
For that we need to construct the packet with the right source and dest
MACs. I understand that we get the source MAC from the bridge port.
However, for the dest MAC we need to look at our ARP table to figure out
the ARP of the directly connected nexthop. This information lies in the
linux kernel -- outside OVS. So how does this interaction happen.

OVS has a packet and then does it do like a data structure lookup to find
out the dest MAC for a given gateway OR does the packet go out of the OVS
and into the Linux kernel for that final processing. If its the latter,
then how does the packet get inserted back into the OVS since it can
finally egress out of eth0 only by using the OVS stack.

Thanks, Abhishek
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