On Wed, Apr 25, 2012 at 10:17:25AM -0700, Jesse Gross wrote: > On Wed, Apr 25, 2012 at 1:39 AM, Simon Horman <ho...@verge.net.au> wrote: > > > > Hi Kyle, > > > > the component that is of most interest to me is enabling OVS to use in-tree > > tunnelling code - as it seems that makes most sense for an implementation > > of STT. I have taken a brief look over your vxlan work and it isn't clear > > to me if it is moving towards being an in-tree implementation. Moreover, > > I'm a rather unclear on what changes need to be made to OVS in order for > > in-tree tunneling to be used. > > > > My recollection is that OVS did make use of in-tree tunnelling code > > but this was removed in favour of the current implementation for various > > reasons (performance being one IIRC). I gather that revisiting in-tree > > tunnelling won't revisit the previous set of problems. But I'm unclear how. > > > > Jesse, is it possible for you to describe that in a little detail > > or point me to some information? > > This was what I had originally written a while back, although it's > more about OVS internally and less about how to connect to the in-tree > code: > http://openvswitch.org/pipermail/dev/2012-February/014779.html > > In order to flexibly implement support for current and future tunnel > protocols OVS needs to be able to get/set information about the outer > tunnel header when processing the inner packet. At the very least > this is src/dst IP addresses and the key/ID/VNI/etc. In the upstream > tunnel implementations those are implicitly encoded in the device that > sends or receives the packet. However, this has a two problems: > number of devices and ability to handle unknown values. We addressed > part of this problem by allowing the tunnel ID to be set and matched > through the OVS flow table and an action. In order to do this with > the in-tree tunneling code, we obviously need a way of passing this > information around since it would currently get lost as we pass > through the Linux device layer. > > The plan to deal with that is to add a function to the in-tree > tunneling code that allows a skb to be encapsulated with specific > parameters and conversely a hook to receive decapsulated packets along > with header info. This would make all of the kernel tunneling code > common, while still giving OVS userspace the ability to implement > essentially any type of tunneling policy. In many ways, this is very > similar to how vlans look in OVS today. > > While it would be possible to implement the hook to use the in-tree > tunnel code today without a lot of changes, we already know that we > want to move away from port-based model in the OVS kernel module > towards the flow model. As we push this upstream the userspace/kernel > API should be the correct one, so that's why these two things are tied > together.
Thanks, that explanation along with Kyle's response helps a lot. It seems to me that something I could help out with is the implementation of the set_tunnel action which extents and replaces the tun_id action. It seems that is a requirement for the scheme you describe above. http://openvswitch.org/pipermail/dev/2012-April/016239.html _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
