[ovs-discuss] Resubmit vs Recirculate

Ben Pfaff blp at nicira.com
Mon Aug 5 20:54:21 UTC 2013


On Mon, Aug 05, 2013 at 12:58:17PM -0700, K.R Kishore wrote:
> Thanks for the quick response. The answer is not clear/complete to
> me, let me rephrase the question based on what I understand.
> 
> - The ofproto-provider which implements the parser and contains the
> - Nicira extension module (for OF) will interpret OF commands and
> - derive flow entries that it plumbs into the datapath. Do commands
> - that require "Resubmit" go only in the user space datapath? Does
> - kernel datapath ever deal with multiple table lookups?

"Resubmit" doesn't require any special support from the datapath.  It
works with any datapath.

> - Secondly, I see a chain of activity
> - (http://openvswitch.org/pipermail/dev/2013-June/028032.html)
> - regarding submission (not release) of "Recirculation" feature into
> - OVS and I can gather from the context of the thread mentioned
> - above that it is related to supporting MPLS packet handling (at
> - least initially).?Does this feature result in entries in the user
> - space datapath table or kernel space table or both? If only the
> - former, what is the packet flow when packets that require
> - "Recirculation"? Does it take the kernel-table miss path? Is there
> - a special flow/path to handle this instead of a miss?

The goal of in-kernel recirculation is to allow the kernel to do more
than one flow lookup for a single packet.  The initial use case is for
MPLS support.  I don't know the details.



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