On Thu, Apr 26, 2012 at 12:13 AM, Simon Horman <ho...@verge.net.au> wrote: > 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
I agree that's probably the best place to start unless Kyle has some specific plans otherwise. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
