Re: [virtio-comment] Re: [PATCH v9] virtio-net: support inner header hash

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Mar 01, 2023 at 11:30:37AM +0800, Heng Qi wrote:
> 
> 
> å 2023/2/28 äå7:16, Michael S. Tsirkin åé:
> > On Sat, Feb 18, 2023 at 10:37:15PM +0800, Heng Qi wrote:
> > > If the tunnel is used to encapsulate the packets, the hash calculated
> > > using the outer header of the receive packets is always fixed for the
> > > same flow packets, i.e. they will be steered to the same receive queue.
> > Wait a second. How is this true? Does not everyone stick the
> > inner header hash in the outer source port to solve this?
> > For example geneve spec says:
> > 
> >     it is necessary for entropy from encapsulated packets to be
> >     exposed in the tunnel header.  The most common technique for this is
> >     to use the UDP source port
> > 
> > same goes for vxlan did not check further.
> > 
> > so what is the problem?  and which tunnel types actually suffer from the
> > problem?
> 
> 
> In fact, similar to protocols such as GRE, there is no outer transport
> header.
> 
> Thanks.


Sorry I don't understand the answer. What is similar to what?
By GRE you mean NVGRE? That has FlowID for this purpose.
Only 8 bit - is this the issue? Not enough entropy?




-- 
MST