[ovs-discuss] Can open vswitch replace libipq?

Hardeep Uppal hardeep.uw at gmail.com
Tue Jul 27 23:20:30 UTC 2010


Hi Ben

Thanks for the reply. I can't seem to find the documentation to the Open
vSwitch API. Could you direct me to it?
Also can Open vSwitch be used to insert flows into the kernel that modify
the packet header to get functionality similar to a NAT?

The documentation for Open vSwitch mentions performance hit when using Open
vSwitch in userspace. Do you have an estimate as to how much the performace
decreases in userspace? I am currently using Xen hypervisor with
2.6.26-2-xen-686 as my dom0 kernel. I can't seem to find the header files
for 2.6.26-2-xen-686  and might have to install Open vSwitch in userspace.

Thanks,

--Hardeep

On Tue, Jul 27, 2010 at 4:03 PM, Ben Pfaff <blp at nicira.com> wrote:

> On Tue, Jul 27, 2010 at 03:49:03PM -0700, Hardeep Uppal wrote:
> > I am trying to find if Open vSwitch can be used to replace libipq? I am
> > currently using libipq for iptables userspace packet queuing. The
> > performance of libipq is not that great and I was wondering if Open
> vSwitch
> > can be used for iptables packet queuing? Is there an Open vSwitch api
> that a
> > user code can make calls to receive packets from a queue, modify the
> packet
> > and reinject it back into the kernel.
>
> Yes, you could probably do this or something similar with Open vSwitch.
> It has all of the right interfaces for receiving a packet from the
> kernel and then reinjecting it.  However, it is not a design goal of
> Open vSwitch to do this kind of this at a high rate.  Instead, Open
> vSwitch tries to install flows directly into the kernel so that packets
> don't have to go to userspace at all.  So I'd have no reason to guess
> that OVS would be better at this than another interface that is designed
> for the purpose.
>
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