[ovs-discuss] Resending request for a new API between controller and switch

[Ben Pfaff]

On Tue, Jan 06, 2015 at 02:38:53PM -0800, Ashok Chippa wrote:
> So, I am reading how OVS datapath works... don't see the details but read
> the following (which I had read before as well):
> 
> - A flow may be identified by any combination of ... (tunnel id, ipv6 nd
> target, ipv4/6 src addr, ip4/6 dst addr, ... etc.)
> - The first packet of the flow is sent to the controller....
> 
> Q1: How does the OVS datapath know that the packet is the first packet?
> Doesn't it identify the flow by some combination of the above packet
> fields? What is thisidentification? Isn't it a flow index that is derived
> by hashing some combination of the above fields? I guess you call it a
> cookie? Okay, lets call it a cookie.
> 
> Q2: When the first packet is sent to the controller, isn't the cookie also
> sent?        All I am requesting is an API that: given any combination of
> (tunnel id, ipv6 nd target. ipv4/6 source address, ...) in an API message,
> returns the cookie... this will be used in the control path (even before
> the first packet hits the datapath)...

I think you're asking for something to extract the packet headers from
an arbitrary packet and report them to the controller.  OpenFlow
doesn't offer that feature.  The appropriate place to request such a
feature would be the OpenFlow extensibility working group.